Selection of potential lactic acid bacteria from fish intestine of mackerel (Rastrelliger kanagurta) from Lembata Regency, East Nusa Tenggara, Indonesia

Aims@#The aim of this study was to screen lactic acid bacteria (LAB) isolates with probiotic properties for tilapia (Oreochromis niloticus) from the intestines of mackerel and to analyze its ability to produce hydrolase enzymes (amylase, protease, cellulase and lipase).@*Methodology and results@#Ten samples of mackerel were collected from the Fish Auction Place, Lewoleba, Nubatukan District, Lembata Regency, East Nusa Tenggara Province, Indonesia. The process for screening were antimicrobial activity, pH tolerance test of 1, 3 and 5, bile salt concentrations of 2.5%, 5% and 7.5%, and water salinity (0.5%, 3.5% and 6.5%). The autoaggregation and semi-qualitative test of hydrolase enzymes were also carried out. In total, 21 LAB isolates were derived from mackerel intestines. Isolates that have the stronger ability to inhibit the pathogen Aeromonas hydrophila ATCC 7966 are KBP 3.3, KBP 3.3.1 and KBP 6.3, while KBP 1.3, KBP 1.1.1 and KBP 3.3.1 were able to inhibit Streptococcus agalactiae ATCC 13813. The LAB isolates that survived at the tested pH were KBP 3.3.1, KBP 3.3, KBP 1.1.1 and KBP 1.3. Results also suggest that the four isolates were tolerant to bile salt concentrations and water salinity with good survival rates (>94.7%) and had proteolytic, lipolytic and cellulolytic activities. The isolates KBP 3.3, KBP 3.3.1 and KBP 1.1.1 were identified as Weissella confusa 6250, while the isolate KBP 1.3 was identified as W. confusa C5-7.@*Conclusion, significance and impact of study@#The characteristics of four selected isolates indicate their potential as a probiotic. These potential probiotic isolates can be applied directly to fish by utilizing microencapsulation technology or adding to the feed.

Antimicrobial and physicochemical characterization of Lactobacillus brevis biofilms as biopreservative agents

Aims@#Lactic acid bacteria (LAB) biofilms constitute one of the most remarkable breakthroughs in the field of food biopreservatives and can be employed to prevent foodborne disease. The purposes of this study were to investigate the efficacy of inhibitory LAB biofilms against foodborne pathogens and evaluate their tolerance to acidic pH and bile salts, as well as their physicochemical properties.@*Methodology and results@#Four strains of Lactobacillus brevis biofilms isolated from kimchi showed antipathogenic activity to the bacteria Staphylococcus aureus FNCC 0049 and Escherichia coli FNCC 0091. These biofilms were also tolerant to pH 2.5, 0.3% bile salt and strong adhesion. Two of the four L. brevis biofilms (L. brevis biofilm KA2 and KB1) produced the highest inhibitory activity against both pathogenic bacterial indicators, tolerance to acidic pH and bile salts, and the strongest adhesion. In addition, based on Scanning Electron Microscope-Energy Dispersion X-ray Spectroscopy (SEM-EDS) analysis, both biofilm strains had a smooth surface texture; the cell morphology was rod-shaped and consisted of several elements such as carbon, oxygen and nitrogen, which was built up of extracellular polymeric substances (EPS).@*Conclusion, significance and impact of study@#The presence of EPS as a constituent of LAB biofilms influenced their survival abilities in an acidic pH and bile salt environment. As a result, the characteristics of L. brevis biofilm KA2 and KB1 made them excellent candidates for use as antimicrobial packaging systems in food biopreservative applications.

Cultivos lácticos como potenciadores de compuestos bioactivos de avena / Lactic starter cultures to improve the oat bioactive compounds

RESUMEN El objetivo de este trabajo fue estudiar la fermentación láctica como bioestrategia para potenciar la actividad antioxidante de la avena. Se evaluó la capacidad de 31 cepas de bacterias lácticas (BL) para adaptarse a un sistema de avena/agua (SAA) mediante la determinación del crecimiento, la acidificación y la actividad fermentativa (método impedimétrico; tiempo de detección [DT], velocidad máxima de cambio de conductabilidad [VMCC] y porcentaje de cambio de conductabilidad [PCC]). Además, se determinó el contenido de compuestos fenólicos (CF) mediante el método de Folin-Ciocalteu (equivalentes de ácido gálico [EAG]), así como de péptidos, de aminoácidos libres y de actividad antirradicalaria (métodos DPPH•y ABTS•+) de los extractos metanólicos y acuosos obtenidos a partir de los SAA fermentados (SAAf). Seis cepas mostraron la mejor adaptabilidad al SAA y produjeron altos valores de VMCC (0,34-0,47 μS/min) y PCC (53,6-66,6%), con bajos valores de DT (≤ 3 h). Estos cambios fueron acompañados por modificaciones en la concentración de CF, péptidos y aminoácidos libres, los cuales fueron dependientes de la cepa. Se evidenció un incremento de la concentración de CF en los SAAf de las seis cepas (29,1-39,85 μg EAG/ml) con respecto al SAA control (17,1 μg EAG/ml). Además, hubo un incremento (9-25,5%) en la actividad antioxidante de los extractos metanólicos de SAAf medida por ambos métodos. Respecto del contenido en péptidos/aminoácidos libres de los SAAf y de su actividad antioxidante, se encontraron modificaciones de menor magnitud. Los resultados muestran que las BL son capaces de adaptarse a la avena como sustrato de fermentación e incrementar su contenido de compuestos antioxidantes.

ABSTRACT The objective of this work was to study lactic fermentation as a biostrategy to enhance the antioxidant activity of oats. The adaptability of 31 strains of lactic bacteria (LB) in an oats/water system (OWS/SAA) was evaluated, measuring growth, acidification and fermentation activity (impedimetric method; detection time [DT], maximum rate of conductance change [MRCC/VMCC] and percentage of conductance change [PCC]). Moreover, the content of phenolic compounds (PC) was determined using the Folin-Ciocalteu method (gallic acid equivalents [GAE]), free peptides and amino acids and free radical scavenging activity (DPPH•and ABTS•+methods) of methanolic and aqueous extracts obtained from fermented OWS/SAAs (fOWS/SAAf) were determined. Six strains have shown the best adaptability to SAA, with high values of VMCC (0.34-0.47 μS/min) and PCC (53.6-66.6%), and low values of DT (≤ 3 h). In these f/OWS/SAAf the chemical composition was also modified (PC concentration, peptides and free amino acids) with strain-dependent behavior. The PC content in f/OWS/SAAf using these six strains (29.1-36.9 μg GAE/ml) was higher than the control content in OWS/SAA control (17.1 ± 1.9 μg GAE/ml). An increase (9-25.5%) in antioxidant activity in f/OWS/SAAf methanolic extracts was detected using both methods. Minor modifications were observed in the peptide and free amino acid content of SAA and their antioxidant activity. Our results show LB ability to adapt to oat as fermentation substrate and increase the content of its antioxidant compounds.

Using PacBio sequencing to investigate the effects of treatment with lactic acid bacteria or antibiotics on cow endometritis

BACKGROUND: Endometritis is the most common disease of dairy cows and traditionally treated with antibiotics. Lactic acid bacteria can inhibit the growth of pathogens and also have potential for treatment of endometritis. Using PacBio single-molecule real-time sequencing technology, we sequenced the fulllength l6S rRNA of the microbiota in uterine mucus samples from 31 cows with endometritis, treated with lactic acid bacteria (experimental [E] group) and antibiotics (control [C] group) separately. Microbiota profiles taken before and after treatment were compared. RESULTS: After both treatments, bacterial species richness was significantly higher than before, but there was no significant difference in bacterial diversity. Abundance of some bacteria increased after both lactic acid bacteria and antibiotic treatment: Lactobacillus helveticus, Lactococcus lactis, Lactococcus raffinolactis, Pseudomonas alcaligenes and Pseudomonas veronii. The bacterial species that significantly decreased in abundance varied depending on whether the cows had been treated with lactic acid bacteria or antibiotics. Abundance of Staphylococcus equorum and Treponema brennaborense increased after lactic acid bacteria treatment but decreased after antibiotic treatment. According to COG-based functional metagenomic predictions, 384 functional proteins were significantly differently expressed after treatment. E and C group protein expression pathways were significantly higher than before treatment (p < 0.05). CONCLUSIONS: In this study, we found that lactic acid bacteria could cure endometritis and restore a normal physiological state, while avoiding the disadvantages of antibiotic treatment, such as the reductions in abundance of beneficial microbiota. This suggests that lactic acid bacteria treatment has potential as an alternative to antibiotics in the treatment of endometritis in cattle.

The effect of electroporation on the growth characteristics and antimicrobial activity of lactic acid bacteria

Aims@#This study aimed to evaluate the effect of electroporation on the growth characteristics and antimicrobial activity of lactic acid bacteria (LAB) including Bifidobacterium longum ATCC 15707, Lactobacillus acidophilus ATCC 314, Lactobacillus casei ATCC 393 and Lactobacillus fermentum ATCC 14931.@*Methodology and results@# Electroporation with the strength of electric field at 1.0–3.0 kV/cm for 2-4 millisecond were applied on the bacterial cultures. All bacterial cultures showed significant (P<0.05) increased in cell viability (40%-325%) upon electroporation. Such treatment also increased the acidity of the cell where the pH of cells decreased upon treatment. In tandem with the increased viability, electroporated bacterial cultures also showed higher proteolytic activity compared to the control (P<0.05). The electroporation treatment also increased (P<0.05) the bacteriocin activity of treated cells compared to the control. However, the molecular weight of bacteriocins produced were not affected by electroporation. Treated cells also possessed better antimicrobial activity. According to the results collected, all treated LAB strains showed 11.5%-113.8% higher (P<0.05) inhibitory activity compared to untreated control against tested pathogenic bacteria, Escherichia coli and Listeria monocytogenes that commonly associated with food contamination. Microarray data analysis showed that electroporation regulated the entities encoding for surface protein and transporter.@*Conclusion, significance and impact of study@#The results from this study suggested that electroporation could enhance the growth characteristics and antimicrobial activity of LAB by modifying the surface regions of the cells. This result may serve as the reference for food manufacturers to opt for effective biopreservation method and produce food with extended shelf life.

Lactic acid bacteria from kefir grains: Potential probiotics with antagonistic activity against multidrug resistant Gram-negative bacteria

Aims@#This study aimed to isolate and identify lactobacilli strains that have antagonistic activity against multidrug resistant (MDR) isolates of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and evaluate their probiotic properties.@*Methodology and results@#Twenty-one Lactobacillus isolates were collected, and their antimicrobial activity was assessed by agar well diffusion, broth microdilution and time-kill test. The probiotic potential of the isolates was evaluated as well. The bacterial culture and cell free supernatant (CFS) of all isolates exhibited antibacterial activity against all MDR isolates. Out of 21 isolates, 4 isolates (A31, B35, S20 and S25) displayed the highest antimicrobial activity and further evaluated. The minimum inhibitory percentages of CFS from selected isolates against pathogens ranged from 10 to 30% and the bactericidal percentages ranged from 20 to 50%. The inhibitory activity of CFS was not changed after heating but abrogated as the pH neutralized. The growth kinetic of the MDR pathogens was significantly reduced in the presence of the CFS of all isolates. The isolates had a less than 1-log reduction in their viability in acid tolerance test and could grow in the presence of 0.3% bile salts. Strains S20, S25 and B35 exhibited high coaggregation with E. coli (51.7-73.3%), P. aeruginosa (53.7-69.3%) and K. pneumoniae (49.7-65.3%). Molecular identification revealed that the isolates were Lactobacillus rhamnosus (B35) and Lactobacillus paracasei (S20, S25, A31). @*Conclusion, significance and impact of study@#The results suggest that these lactobacilli isolates may have potential applications for controlling and preventing colonization of infections caused by MDR pathogens.

Isolation and characterization of lactic acid bacteria from sugarcane waste

Aims@#Researchers are focusing more on the isolation of new probiotic bacteria to increase varieties for the growing market demand. This study aimed to isolate lactic acid bacteria (LAB) strains from sugarcane waste materials and evaluate its characteristic. @*Methodology and results@#In the present study, two strains of LAB (Isolates A and B) were isolated from sugarcane waste and investigated in vitro for their characteristics as potential probiotics. These isolates were evaluated on their characteristics based on four biochemical tests (acid tolerance, bile tolerance, microbial adhesion, and phenol resistance), with the commercial strain Lactobacillus isolated from Yakult ® served as a positive control. Both isolated strains (>8 log10 CFU/mL) displayed higher survivability than control (>6 log10 CFU/mL) in simulated gastrointestinal conditions at pH 2.0 and pH 6.9 after 24 h. Furthermore, both isolated LABs were resistant to inhibitory substances which are 0.05-0.3% bile and 0.4% phenol. For bile tolerance, isolate A (OD 6.83) had a higher absorbance at 0.3% bile concentration as compared to isolate B (OD 2.20). However, isolate B (7.49 log10 CFU/mL) showed higher resistance towards 0.4% phenol than isolate A (7.11 log10 CFU/mL) after 24 h. Both isolate A and isolate B displayed low cell surface hydrophobicity, strong electron donor, and basic characteristic.@*Conclusion, significance and impact of study@#Both isolates were able to survive under gastrointestinal stress conditions, implying their potential as probiotics. This study demonstrated that valuable products such as probiotic strain could be isolated from sugarcane wastes to use in food production or medical treatment.

Isolation and characterization of Lactobacillus brevis C23 with ability to secrete antimicrobial substance for the inhibition of a foodborne pathogen Listeria monocytogenes ATCC 7644

Aims@#This study aims to isolate lactic acid bacteria (LAB) from various food sources to obtain a potent strain against Listeria monocytogenes. @*Methodology and results@#A total of 68 LAB isolates were selected to evaluate their antimicrobial activity against L. monocytogenes, a foodborne pathogen and a causative agent of listeriosis. The selected isolate was identified and characterized. The isolate C23 from cabbage showed the highest antimicrobial activity against L. monocytogenes ATCC 7644 with inhibition ability of 73.94%. The isolate was closely related to Lactobacillus brevis by 16S rRNA sequencing and subsequently deposited in GenBank with an accession number of MN880215, named as L. brevis C23. The cell free supernatant (CFS) of L. brevis C23 had high tolerance in low pH and was able to withstand up to 60 °C. The proteinaceous nature of the antimicrobial agent was also confirmed through the enzymatic test. The CFS was stable on different detergents as well as bile salts. Under transmission electron microscopy (TEM), the inhibitory effect of CFS against L. monocytogenes was proven by causing cell lysis.@*Conclusion, significance and impact of study@#Bacteriocin-like inhibitory substances (BLIS) of L. brevis C23 showed very promising potential in food industrial application.

Advances in the use of lactic acid bacteria as mucosal delivery vectors of therapeutic molecules / 生物工程学报

Lactic acid bacteria (LAB) are generally recognized as safe food-grade microorganisms and are widely used in food production, preservation, and as probiotics to promote human health. Given the need to develop effective drug delivery strategies, LAB have become attractive live vehicles for the oral, intranasal and vaginal delivery of therapeutic molecules. Being live and safe organisms, LAB are able to directly produce and deliver target proteins for therapeutic purpose, which remarkably reduces the cost for drug production. To date, LAB have been used to deliver a variety of functional proteins to mucosal tissues for the treatment of various diseases. This review summarized the development and application of LAB as mucosal delivery vectors in the last 20 years to provide references for future clinical research.

A comparative profile of bactericidal action of a partially purified bacteriocin from lactic acid bacteria with antibiotics

Aims@#The menace of antibiotic resistance has led to the search for alternatives, which in turn has diverted the attention to bacteriocins, antimicrobial peptides (AMPs) produced by bacteria for their bactericidal properties. The aim of our study was to isolate and partially purify bacteriocin from lactic acid bacteria (LAB) and comparing its antimicrobial activity with antibiotics.@*Methodology and results@#Among 38 LAB screened using agar spot assay, LAB 28D1 showed the highest antimicrobial activity against the test bacterial strains. The proteinaceous nature of the antimicrobial compound extracted from LAB 28D1 was confirmed by its inactivation after treatment with proteolytic enzymes. The crude bacteriocin was found to be stable over a wide range of temperatures (60-100 °C) and pH (4-9). The bacteriocin was partially purified by ammonium sulfate precipitation (ASP) and the activity units were 204,800 AU/mL. The total protein and the specific activity of partially purified bacteriocin were found to be 24.585 mg and 124,954.24 AU/mg respectively. The molecular weight of partially purified bacteriocin was determined to be 8.5 kDa approximately. The efficacy of the partially purified bacteriocin against indicator bacterial strains was compared with antibiotics by the disc diffusion method and minimum inhibitory concentration (MIC). According to our study, the hospital waste isolate Enterococcus spp. was found to be multidrug-resistant (MDR) but sensitive to bacteriocin from LAB (MIC 0.06 ± 0 µg/mL).@*Conclusion, significance and impact of the study@#Bacteriocin from LAB has potential in combating MDR enterococcal infections.

Atividade antagonista in vitro de bactérias ácido láticas isoladas de queijo de coalho artesanal do Sertão paraibano frente a microrganismos indicadores / Antagonist activity in vitro of lactic acid bacteria isolated from coalho cheese from Sertão paraibano front microorganisms indicators

Bactérias ácido láticas (BAL) produzem substâncias inibitórias de patógenos e deteriorantes de alimentos e isso tem despertado interesse sobre seu uso na preservação e na segurança sanitária desses produtos. Assim, o estudo foi realizado com o objetivo de avaliar a atividade inibitória de Streptococcus infantarius subsp. infantarius isoladas de queijo de coalho artesanal do Sertão da Paraíba frente a microrganismos indicadores. A avaliação do potencial antagônico foi realizada pela técnica de difusão em disco frente à estirpe reveladora Escherichia coli, isolada das mesmas amostras de queijos e frente ao patógeno de referência Escherichia coli ATCC 3539. Das 11 estirpes analisadas, 81,8% foram capazes de inibir o microrganismo indicador isolado dos mesmos queijos de coalho, enquanto 36,4% das bactérias láticas apresentaram inibição frente ao patógeno de referência. Conclui-se que as cepas Streptococcus infantarius subsp. infantarius isoladas de queijos de coalho do Sertão da Paraíba apresentam potencial antagônico e podem assegurar a qualidade microbiológica de alimentos fermentados, inclusive o queijo de coalho.(AU)

Lactic acid bacteria (BAL) produce pathogen inhibiting and food damaging substances and this has raised interest in their use in the preservation and health safety of these products. Thus, the study was carried out with the objective of evaluating the inhibitory activity of Streptococcus infantarius subsp. infantarius isolated from artisanal coalho cheese from Sertão da Paraíba against indicator microorganisms. The evaluation of the antagonistic potential was performed using the disk diffusion technique against the Escherichia coli revealing strain, isolated from the same cheese samples and against the reference pathogen Escherichia coli ATCC 3539. Of the 11 strains analyzed, 81.8% were able to inhibit the indicator microorganism isolated from the same coalho cheeses, while 36.4% of the lactic acid bacteria showed inhibition compared to the reference pathogen. It is concluded that the strains Streptococcus infantarius subsp. infantarius isolated from coalho cheeses from Sertão da Paraíba have antagonistic potential and can ensure the microbiological quality of fermented foods, including coalho cheese.(AU)

Quantification of biogenic amines in fabrication steps of Gorgonzola-type cheese / Quantificação de aminas biogênicas nas etapas de fabricação do queijo tipo Gorgonzola

During the Gorgonzola-type cheese preparation there are proteolysis and lipolysis which may be influenced by the type of starter culture chosen. Six manufacturing steps were selected to identify which of them is most suitable for biogenic amines (BA) formation (1- milk, 2- lactic acid bacterial culture and fungus addition, 3- curd, 4- dry salting, 5- maturation at 30 days and maturation at 60 days); perform research on enterobacteria; accomplish the research of BA-producing bacteria (BAPB); detect and quantify the most abundant BA (putrescine, cadaverine, tyramine, histamine, spermidine and spermine) in the six steps of Gorgonzola cheese production and in bacterial isolates using high performance liquid chromatography and UV-Vis SPD/10AV detector and define if the presence of enterobacteria and BAPB would be correlated with BA production in this cheese. The bacterial culture used increased its log population by 7 log cycles and reached its highest level in batch 2 during cheese maturation. There was a decrease in the enterobacterial population in 2 log cycles after 60 days of maturation in batch 1. Tyramine was the BA with the highest concentration 306.32 mg.Kg-1 quantified in step 6 (60 days maturation) in batch 1. Criterion is requiered in bacterial starter culture selection because it is a quality determinant factor in relation to BA production and more rigor in raw material selection.

Durante a elaboração do queijo tipo Gorgonzola ocorre proteólise a partir das bactérias e dos fungos adicionados ao leite que podem levar a formação de aminas biogênicas (AB) neste tipo de queijo. Portanto, no presente estudo foi feito o acompanhamento com coleta de amostras em seis etapas na fabricação deste queijo paraidentificar em qual delas haveria maior formação de aminas biogênicas (AB). As amostras coletadas em três diferentes lotes foram o leite cru (1), leite pasteurizado adicionado de cultura de bactérias ácido-láticas (2), massa coalhada (3), queijo após a etapa de salga seca (4), queijo após 30 dias de maturação (5) e queijo após 60 dias de maturação (6). Também foram realizadas a pesquisa de enterobactérias e bactérias ácido-láticas com característica capacidade de descarboxilação de aminoácidos e produção de aminas biogênicas (BPAB); detecção e quantificação da AB mais abundante (putrescina, cadaverina, tiramina, histamina, espermidina e espermina) nas seis etapas de fabricação do queijo tipo Gorgonzola e nos isolados bacterianos utilizando cromatografia líquida de alta eficiência e detector UV-Vis SPD/10AV e a verificação se a presença de enterobactérias e BPAB estariam correlacionadas com a produção de AB nesse queijo. A cultura bacteriana utilizada cresceu aumentando em sete ciclos logarítmicos sua população e alcançou seu maior nível no lote 2 na etapa de maturação do queijo. Houve diminuição da população enterobactérias em 2 ciclos logarítmicos após 60 dias de maturação no lote 1. A tiramina foi a AB com concentração mais elevada 306,32 mg.Kg-1 quantificada na etapa 6 (60 dias de maturação) no lote 1. É necessário dar mais atenção em duas etapas na elaboração dos queijos: mais critério na seleção da cultura bacteriana iniciadora por ser um fator determinante na qualidade em relação à produção de AB e mais rigor na seleção da matéria-prima.Palavras chaves: cromatografia, cultura iniciadora, detector SPD/10AV UV­Vis, maturação, tiramina.

Influencia del tipo de nacimiento sobre el contenido de bacterias acidolácticas en meconio de neonatos* / Influence from the type of birth on the content of lactic acid bacteria in neonate meconium

RESUMEN El objetivo del estudio fue determinar la influencia del nacimiento por vía vaginal en comparación con el nacimiento por cesárea sobre el contenido de bacterias acidolácticas con características probióticas de los recién nacidos. Se evaluaron muestras de meconio de recién nacidos por vía vaginal y por cesárea que fueron debidamente enriquecidas, sembradas e incubadas. Las colonias resultantes fueron identificadas para ser sometidas a tolerancia de sales biliares, pH ácido y fermentación. Se obtuvo un mayor desa rrollo de colonias en meconio de nacidos por vía vaginal en comparación con los nacidos por cesárea (p<0,001). Se aislaron 48 cepas en total, siendo en su gran mayoría tolerantes a sales biliares y pH ácido; asimismo, la fermentación de lactosa en leche fue positiva. Este estudio respalda hallazgos previos que sustentan que el nacimiento por vía vaginal favorece al mayor, desarrollo de bacterias acidolácticas con características probióticas, en comparación con el nacimiento por cesárea, y destaca la presencia de bac terias del género Lactobacillus.

ABSTRACT The study's objective was to determine the influence of vaginal birth compared to cesarean birth on the content of lactic acid bacteria with probiotic characteristics from newborns. Vaginal and cesarean sec tion meconium samples of lactic acid were evaluated, which were duly enriched, seeded and incubated. The resulting colonies were identified to be subjected to bile salt tolerance, acid pH, and fermentation. A greater development of meconium colonies was obtained in those born vaginally compared to those born by caesarean section (p <0.001). A total of 48 strains were isolated, the majority being tolerant to bile salts and acid pH; likewise, the fermentation of lactose in milk was positive. This study supports previous findings that support vaginal birth favors the greatest development of lactic acid bacteria with probiotic characteristics, compared to cesarean birth, and highlights the presence of bacteria of the genus Lactobacillus.

Desenvolvimento de sorvete de kefir com polpa de manga: avaliação sensorial, físico-química e de bactérias ácido láticas / Development of kefir ice cream with mango pulp: sensory evaluation, physico-chemistry and lactic acid bacteria

O kefir é uma bebida probiótica que contribui com benefícios à saúde. A sua utilização em preparações como o sorvete contribui para incorporação de micro-organismos probióticos na formulação podendo estimular seu consumo com objetivo funcional, por meio de uma sobremesa apreciada entre os consumidores. O trabalho objetivou analisar as características sensoriais, físico-químicas e microbiológicas de sorvetes caseiros desenvolvidos com kefir e polpa de manga. A formulação 1 do sorvete foi elaborada com kefir à 5% e a formulação 2 com kefir a 10% (m/v) e avaliadas quanto a aceitação, pH, acidez titulável e contagem de BAL. As análises microbiológicas foram realizadas no leite integral, kefir à 5% e 10 % m/v e nos sorvetes antes do congelamento (T0), após o congelamento final (T29 h) e após uma semana do congelamento (T168 h). O pH do kefir a 5 % diferiu (p < 0,05) daquele encontrado no de 10%. A análise sensorial mostrou que as formulações foram bem aceitas (p > 0,05) em todos os atributos. Após T168 h os sorvetes apresentaram contagem BAL igual a 2,7 x107 para a formulação 1 e 1,1 x108 UFC/mL para a formulação 2. Conclui-se que o kefir apresentou características de um leite fermentado e que o sorvete de kefir com polpa de manga à 5% e 10% apresentaram após T168 h contagem mínima de bactérias ácido lácticas prevista na legislação (AU)

Kefir is a probiotic drink that contributes health benefits. Its use in preparations such as ice cream can stimulate its consumption through a dessert appreciated among consumers, in addition to allowing the ingestion of lactic acid bacteria. The objective of this work was to analyze the sensorial, physicalchemistry and microbiological characteristics of homemade ice creams developed with kefir and mango pulp. Formulation 1 of the ice cream was made with kefir at 5% and formulation 2 with kefir at 10%, (w/v) and was evaluated for acceptance, pH, titratable acidity and lactic acid bacteria count. Microbiological analyzes were performed in whole milk, kefir at 5% and 10%, and in ice cream before freezing (T0), after the final freezing (T29 h) and after one week of freezing (T168 h). The pH of the kefir at 5% differed (p <0.05) from that found in 10%. Sensory analysis showed that the formulations were accepted (P> 0.05) in all attributes. After T168 h, the ice creams had a lactic acid bacteria count (AU)

Technology and safety assessment for lactic acid bacteria isolated from traditional Bulgarian fermented meat product "lukanka"

Abstract The present work discusses the technological and new selection criteria that should be included for selecting lactic acid bacteria for production of fermented meat. Lactic acid bacteria isolated from Bulgarian traditional fermented "lulanka" salami was studied regarding some positive technological parameters (growth at different temperature, pH, and proteolytic activity). The presence of genes related to the virulence factors, production of biogenic amines, and vancomycin resistance were presented in low frequency in the studied lactic acid bacteria. On the other hand, production of antimicrobial peptides and high spread of bacteriocin genes were broadly presented. Very strong activity against L. monocytogenes was detected in some of the studied lactic acid bacteria. In addition, the studied strains did not present any antimicrobial activity against tested closely related bacteria such as Lactobacillus spp., Lactococcus spp., Enterococcus spp. or Pediococcus spp. To our knowledge this is the first study on the safety and antimicrobial properties of lactic acid bacteria isolated from Bulgarian lukanka obtained by spontaneous fermentation.

Influencia del aceite esencial de orégano en la elaboración tradicional de quesos: efecto sobre el fermento láctico / Influence of oregano essential oil on traditional Argentinean cheese elaboration: Effect on lactic starter cultures

The aim of this work is to study the oregano essential oil (OEO) composition from Northwestern Argentinean regions and to evaluate its effect on the lactic starter cultures. The oregano used, Origanum vulgare var hirtum, was obtained from Andalgalá, Catamarca. The essential oil presented high amounts of α-terpinene (10%), γ-terpinene (15.1%), terpinen-4-ol (15.5%) and thymol (13.0%) as the main components. No negative effect on growth or metabolic activity of lactic acid bacteria Streptococcus thermophilus CRL 728 and CRL 813, Lactobacillus delbrueckii subsp. bulgaricus CRL 656 and CRL 468, and Lactococcus lactis subsp. lactis CRL 597 up to the maximum concentration (200 μg/g) assayed was observed. No differences in the organoleptic characteristics of semi-hard cheeses flavored with oregano essential oil (200 μg/g) and homemade cheeses flavored with oregano leaves were found. With respect to the microbiological quality of the products, neither enterobacteria nor mold and yeast were detected during ripening in essential-oil flavored cheese compared to control cheese (enterobacteria 2 × 10³ UFC/g) and cheese flavored with oregano leaves (mold/yeast 4 × 10(4) CFU/g). Our results showed that the use of oregano essential oil and lactic starter culture considerably improved cheese quality.

El objetivo de este trabajo fue estudiar la composición del aceite esencial de orégano recolectado en el noroeste argentino y evaluar su efecto sobre algunos fermentos lácticos. El orégano recolectado correspondió a la especie Origanum vulgare var. hirtum proveniente de Andalgalá, Catamarca. En su aceite esencial (obtenido por arrastre con vapor de agua) se detectó principalmente α-terpineno (10%), γ-terpineno (15,1%), terpinen-4-ol (15,5%) y timol (13,0%). El aceite esencial no tuvo efecto inhibitorio (máxima concentración ensayada 200 μg/g) sobre el crecimiento ni sobre la actividad metabólica de Streptococcus thermophilus CRL 728 y CRL 813, de Lactobacillus delbrueckii subsp. bulgaricus CRL 656 y CRL 468, y de Lactococcus lactis subsp. lactis CRL 597. No se observaron diferencias en las características organolépticas de quesos semiduros aromatizados con el aceite esencial (200 μg/g) comparados con quesos artesanales aromatizados con hojas de orégano. Respecto de la calidad microbiológica de los productos, no se detectaron enterobacterias ni hongos o levaduras durante la maduración en los quesos aromatizados con el aceite esencial de orégano comparados con los quesos control, que presentaron desarrollo de enterobacterias (2 × 10³ UFC/g), y con los quesos elaborados con hojas de orégano, en los que hubo desarrollo de hongos/levaduras (4 × 10(4) CFU/g). Los resultados obtenidos demostraron que el uso del aceite esencial de orégano y del fermento láctico incrementó la calidad general de los quesos artesanales.

Prevalence of lactic acid bacteria in sliced cooked ham as an indicator of its shelf life / Prevalencia de bacterias de ácido láctico en jamón cocido friccionado como indicador de su vida útil

Background: Ready to eat sliced-cooked-meat-products (RTE) are popular convenience foods. Slicing of such products at retail point is a common practice in supermarkets. Due to handling, as well as the supermarket environment, it has been suggested that the counts and presence of specific lactic acid bacteria (LAB) in these products may be associated with their rapid deterioration and short shelf life. Objectives: The aim was to quantify and identify LAB in commercial sliced cooked ham. Methods: Thirty samples of sliced cooked ham were collected from five supermarkets. Each sample was analyzed in terms of: Lactobacillus on De Man Rogosa, Sharpe agar (30°C), mesophilic (30°C) and thermophilic (37ºC) Streptococcus on M17 agar containing 1% lactose, Lactococcus on LM17 agar containing 100 µg per liter of cycloheximide (25°C) and Enterococci on Kanamicin Aesculin Azide agar containing kanamycin (37°C), all under anaerobic conditions (Gas-Pack System®, BBL) for 48-72h. Twenty-one colonies were randomly picked and physiologically and biochemically characterized. Results: No difference was observed in genuses between supermarkets; however, significant differences were observed between microbial genuses. Enterococci showed the lowest count (2.34 ± 0.05 log10 CFU/g) and Lactobacilli had the highest counts (5.98 ± 0.04 log10 CFU/g). Of the strains isolated 23.8% were identified as thermophillic Lactobacillus, 23.8% mesophilic Lactobacillus, 28.6% Enterococcus, 14.3% Lactococcus and 9.5% Streptococcus. From these, only six could be characterized to species level; one was L.lactis subsp. lactis and five were L. amylolyticus. Conclusions: High LAB counts are a common cause of spoilage in RTE meat products, since these are commonly found in meat environments. Therefore a study on the processing, distribution and in-site handling of RTE meat products at supermarkets may be necessary in order to increase its shelf life.

Antecedentes: Los productos cárnicos rebanados cocidos listos para el consumo (RTE) son alimentos populares de conveniencia. El rebanado de este tipo de productos es una práctica común en los supermercados. Debido a la manipulación, así como al entorno del supermercado, se ha sugerido que los recuentos y la presencia de bacterias ácido lácticas (LAB) en estos productos pueden estar asociados con su rápido deterioro y corta vida en anaquel. Objetivo: El objetivo de este trabajo fue cuantificar e identificar LAB en jamón cocido rebanado en el supermercado. Métodos: se recolectaron 30 muestras de jamón cocido rebanado de cinco supermercados. Cada muestra se analizó en términos de: Lactobacillus en agar De Man Rogosa, Sharpe (30°C), Streptococcus mesofílicos (30°C) y termofílicos (37°C) en agar M17 conteniendo 1% de lactosa, Lactococcus en agar LM17 contiendo 100 µg por litro de ciclohexamida (25°C), y Enterococci en agar Kanamicin Aesculin Azide conteniendo kanamicina (37°C), todos bajo condiciones anaeróbicas (Gas-Pack System®, BBL) por 48-72h. Veintiún colonias seleccionadas al azar fueron fisiológica y bioquímicamente caracterizadas. Resultados: No se observaron diferencias en el género entre los supermercados; sin embargo, se observaron diferencias significativas entre género microbiano. Los enterococos mostraron los recuentos más bajos (2,34 ± 0,05 log10 CFU/g) y los lactobacilos los más altos (5,98 ± 0,04 log10 CFU/g). De las cepas aisladas 23,8% fueron identificados como Lactobacillus termófilos, 23,8% Lactobacillus mesófilos, 28,6% Enterococcus, 14,3% Lactococcus y 9,5% Streptococcus. De éstos, sólo seis pudieron caracterizarse a nivel de especie; uno fue L.lactis subsp lactis y cinco fueron L. amylolyticus. Conclusiones: Conteos altos de LAB son una causa común del deterioro de los productos cárnicos listos para el consumo, ya que estos se encuentran comúnmente en los entornos donde se maneja carne. Por lo tanto, es necesario llevar a cabo un estudio sobre el procesamiento, distribución y manejo de productos cárnicos listos para el consumo en los supermercados con el fin de aumentar su vida en anaquel.

Characterization of the spoilage lactic acid bacteria in “sliced vacuum-packed cooked ham”

The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc/Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus, following by Lactobacillus sakei and Leuconostoc mesentereoides; the Enterococcus sp. was not present in the samples.

Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products

A total of 244 lactic acid bacteria (LAB) strains were isolated from 180 dairy and pharmaceutical products that were collected from different areas in Minia governorate, Egypt. LAB were identified phenotypically on basis of morphological, physiological and biochemical characteristics. Lactobacillus isolates were further confirmed using PCR-based assay. By combination of phenotypic with molecular identification Lactobacillus spp. were found to be the dominant genus (138, 76.7%) followed by Streptococcus spp. (65, 36.1%) and Lactococcus spp. (27, 15%). Some contaminant organisms such as (Staphylococcus spp., Escherichia coli, Salmonella spp., mould and yeast) were isolated from the collected dairy samples but pharmaceutical products were free of such contaminants. Susceptibility of LAB isolates to antibiotics representing all major classes was tested by agar dilution method. Generally, LAB were highly susceptible to Beta-lactams except penicillin. Lactobacilli were resistant to vancomycin, however lactococci and streptococci proved to be very susceptible. Most strains were susceptible to tetracycline and showed a wide range of streptomycin MICs. The MICs of erythromycin and clindamycin for most of the LAB were within the normal range of susceptibility. Sixteen Lactobacillus,8 Lactococcus and 8 Streptococcus isolates including all tetracycline and/or erythromycin resistant strains were tested for the presence of tetracycline and/or erythromycin resistant genes [tet(M) and/or erm(B)]. PCR assays shows that some resistant strains harbor tet(M) and/or erm(B) resistance genes.

The influences of fish infusion broth on the biogenic amines formation by lactic acid bacteria

The influences of fish infusion decarboxylase broth (IDB) on biogenic amines (BA) formation by lactic acid bacteria (LAB) were investigated. BA productions by single LAB strains were tested in five different fish (anchovy, mackerel, white shark, sardine and gilthead seabream) IDB. The result of the study showed that significant differences in ammonia (AMN) and BA production were observed among the LAB strains in fish IDB (p < 0.05). The highest AMN and TMA production by LAB strains were observed for white shark IDB. The all tested bacteria had decarboxylation activity in fish IDB. The uppermost accumulated amines by LAB strains were tyramine (TYM), dopamine, serotonin and spermidine. The maximum histamine production was observed in sardine (101.69 mg/L) and mackerel (100.84 mg/L) IDB by Leuconostoc mesenteroides subsp. cremoris and Pediococcus acidophilus, respectively. Lactobacillus delbrueckii subsp. lactis and Pediococcus acidophilus had a high TYM producing capability (2943 mg/L and 1157 mg/L) in sardine IDB.