Dynamic changes of total acid and bacterial communities during the traditional fermentation of Hong Qu glutinous rice wine

Background: Hong Qu glutinous rice wine (HQGRW) is brewed under non-aseptic fermentation conditions, so it usually has a relatively high total acid content. The aim of this study was to investigate the dynamics of the bacterial communities and total acid during the fermentation of HQGRW and elucidate the correlation between total acid and bacterial communities. Results: The results showed that the period of rapid acid increase during fermentation occurred at the early stage of fermentation. There was a negative response between total acid increase and the rate of increase in alcohol during the early fermentation stage. Bacterial community analysis using high-throughput sequencing technology was found that the dominant bacterial communities changed during the traditional fermentation of HQGRW. Both principal component analysis (PCA) and hierarchical clustering analysis revealed that there was a great difference between the bacterial communities of Hong Qu starter and those identified during the fermentation process. Furthermore, the key bacteria likely to be associated with total acid were identified by Spearman's correlation analysis. Lactobacillus, unclassified Lactobacillaceae, and Pediococcus were found, which can make significant contributions to the total acid development (| r| N 0.6 with FDR adjusted P b 0.05), establishing that these bacteria can associate closely with the total acid of rice wine. Conclusions: This was the first study to investigate the correlation between bacterial communities and total acid during the fermentation of HQGRW. These findings may be helpful in the development of a set of fermentation techniques for controlling total acid.

Antifungal Activity of Lactic Acid Bacteria Strains Isolated from Natural Honey against Pathogenic Candida Species

The role of lactic acid bacteria (LAB) in honey as antifungal activity has received little attention and their mechanism of inhibitory of fungi is not fully understood. In this study, LAB were isolated from honey samples from Malaysia, Libya, Saudi Arabia, and Yemen. Twenty-five isolates were confirmed LAB by catalase test and Gram staining, and were screened for antifungal activity. Four LAB showed inhibitory activity against Candida spp. using the dual agar overlay method. And they were identified as Lactobacillus plantarum HS isolated from Al-Seder honey, Lactobacillus curvatus HH isolated from Al-Hanon honey, Pediococcus acidilactici HC isolated from Tualang honey and Pediococcus pentosaceus HM isolated from Al-Maray honey by the 16S rDNA sequence. The growth of Candida glabrata ATCC 2001 was strongly inhibited (>15.0 mm) and (10~15 mm) by the isolates of L. curvatus HH and P. pentosaceus HM, respectively. The antifungal activity of the crude supernatant (cell free supernatant, CFS) was evaluated using well diffusion method. The CFS showed high antifungal activity against Candida spp. especially The CFS of L. curvatus HH was significantly (p < 0.05) inhibited growth of C. glabrata ATCC 2001, C. parapsilosis ATCC 2201, and C. tropicalis ATCC 750 with inhibitory zone 22.0, 15.6, and 14.7 mm, respectively. While CFS of P. pentosaceus HM was significantly (p < 0.05) effective against C. krusei, C. glabrata, and C. albicans with inhibition zone 17.2, 16.0, and 13.3 mm, respectively. The results indicated that LAB isolated from honey produced compounds which can be used to inhibit the growth of the pathogenic Candida species.

Purified dextransucrase from Pediococcus pentosaceus CRAG3 as food additive.

The extracellular crude dextransucrase (0.67 U/mg) from P. pentosaceus CRAG3 (GenBank accession number JX679020) after PEG-1500 fractionation gave specific activity, 20.0 U/mg which by gel filtration resulted in 46.0 U/mg. The purified dextransucrase displayed molecular size of approximately, 224 kDa. The optimum assay conditions for dextransucrase activity were 5% sucrose in 20 mM sodium acetate buffer (pH 5.4) and 30 oC. The dextransucrase was stable up to 40 oC and at pH range of 5.4-7.0. The metal ions such as Co2+, Ca2+, Mg2+ and Zn2+ stimulated the dextransucrase activity by 56, 44, 14 and 12%, respectively. It was most stable at -20 oC with half-life of 307 days. Amongst various additives used, glycerol and Tween 80 provided significant stability to the enzyme with half-life 15.5 and 85.5 h, respectively as compared to control (6.9 h). The solidification of sucrose supplemented milk by purified dextransucrase due to dextran synthesis displayed its application as additive for improving the texture of dairy products.

Pathogen translocation and histopathological lesions in an experimental model of Salmonella Dublin infection in calves receiving lactic acid bacteria and lactose supplements

The purpose of this study was to evaluate the capacity of a lactic acid bacteria (LAB) inoculum to protect calves with or without lactose supplements against Salmonella Dublin infection by evaluating histopathological lesions and pathogen translocation. Fifteen calves were divided into three groups [control group (C-G), a group inoculated with LAB (LAB-G), and a group inoculated with LAB and given lactose supplements (L-LAB-G)] with five, six, and four animals, respectively. The inoculum, composed of Lactobacillus (L.) casei DSPV 318T, L. salivarius DSPV 315T, and Pediococcus acidilactici DSPV 006T, was administered with milk replacer. The LAB-G and L-LAB-G received a daily dose of 109 CFU/kg body weight of each strain throughout the experiment. Lactose was provided to the L-LAB-G in doses of 100 g/day. Salmonella Dublin (2 x 1010 CFU) was orally administered to all animals on day 11 of the experiment. The microscopic lesion index values in target organs were 83%, 70%, and 64.3% (p < 0.05) for the C-G, LAB-G, and L-LAB-G, respectively. Administration of the probiotic inoculum was not fully effective against infection caused by Salmonella. Although probiotic treatment was unable to delay the arrival of pathogen to target organs, it was evident that the inoculum altered the response of animals against pathogen infection.

Screening of food-grade microorganisms for biotransformation of D-tagatose and cloning and expression of L-arabinose isomerase / 生物工程学报

L-Arabinose isomerase (L-AI) is an intracellular enzyme that catalyzes the reversible isomerization of D-galactose and D-tagatose. Given the widespread use of D-tagatose in the food industry, food-grade microorganisms and the derivation of L-AI for the production of D-tagatose is gaining increased attention. In the current study, food-grade strains from different foods that can convert D-galactose to D-tagatose were screened. According to physiological, biochemical, and 16S rDNA gene analyses, the selected strain was found to share 99% identity with Pediococcus pentosaceus, and was named as Pediococcus pentosaceus PC-5. The araA gene encoding L-AI from Pediococcus pentosaceus PC-5 was cloned and overexpressed in E. coli BL21. The yield of D-tagatose using D-galactose as the substrate catalyzed by the crude enzyme in the presence of Mn2+ was found to be 33% at 40 degrees C.

Influence of the probiotic pediococcus acidilactici on chromosomal aberrations, clinicopathological alterations and immunological changes in aflatoxicated rabbits

The present work was carried out to evaluate the effectiveness of the probiotic Pediococcus acidilactici in alleviating the toxicity of aflatoxin B[1] [AFB[1]] in male New-Zealand white rabbits. Twenty four male New Zealand white rabbits, 800-1000 g body weight were used in the present work. Rabbits were randomly divided into four equal groups: Group [1] served as a control group. Group [2] was fed on crushed pellet diet mixed with the probiotic Pediococcus acidilactici at a dose of l00g/ton feed for six successive weeks. Group [3] was fed on crushed pellet diet artificially contaminated with 60 ug of AFB[1]/kg of diet for six successive weeks while Group [4] was fed on crushed pellet diet mixed with the probiotic Pediococcus acidilactici [the same dose mentioned in G2] and artificially contaminated with 60 ug of AFB[1]/kg of diet for six successive weeks. Evaluations were made for chromosomal aberrations, hemato-biochemical parameters, immunological changes as well as histopathological alterations. Our results showed that AFB[1] possesses a mutagenic effect. It significantly increases the frequency of chromosomal aberrations. AFB[1]induced significant decrease in the total leukocytic count associated with lympopenia. Serum biochemical analysis revealed significant elevation in ALT, AST, GGT activities and BUN concentration with a marked decline in total proteins, albumin and globulins concentration. Significant decrease was recorded in the phagocytic percent and phagocytic index of neutrophils of aflatoxicated rabbits. Supplementation of the probiotic Pediococcus acidilactici to the aflatoxicated diet inhibited the mutagenic effect of AFB[1] as it significantly decreased the frequency of chromosonial aberrations. Furthermore, Pediococcus acidilactic improved the hemato-biochemical alterations and nullified the phagocytic percent and phagocytic index of neutrophils of aflatoxicateci rabbits

Heterologous expression, purification and refolding of an anti-listerial peptide produced by Pediococcus acidilactici K7

The fusion protein, 6XHis-Xpress-PedA was constructed and expressed in Escherichia coli BL21 (DE3). The presence of a 12.8 kDa recombinant protein, localized in inclusion bodies (IBs) at high concentration, was confirmed by SDS-PAGE analysis and by western blotting using anti-His antibody. The rec-pediocin was purified by Nickel-nitrilotriacetic acid beads and refolded using 5 mM of beta-mercaptoethanol along with 1 M glycine. Results indicated that the refolded rec-pediocin had an early elution profile in the RP-HPLC when compared to the unfolded protein and it exhibited biological activity against Listeria monocytogenes V7 which was approximately 25 times less active compared to native counterpart. The final yield of purified rec-pediocin was 3 mg/l of the culture and is estimated to be 8-10 times higher than the purification by conventional methods.

Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process / Exploración del uso de agentes antimicrobianos naturales y de campos eléctricos pulsantes para el control de bacterias contaminantes durante el proceso de elaboración de cerveza

Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 °C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage.

Diferentes antimicrobianos naturales disminuyeron la viabilidad de bacterias contaminantes aisladas en etapas críticas del proceso de producción de cerveza. En un extracto de malta, el agregado de 1 mg/ml de quitosano y de 0,3 mg ml de lúpulo permitió reducir la viabilidad de Escherichia coli a 0,7 y 0,1%, respectivamente, al cabo de 2 horas de incubación a 4 °C. El agregado de 0,0002 mg/ml de nisina, 0,1 mg/ml de quitosano o de 0,3 mg/ml de lúpulo inhibió selectivamente (10.000 veces más) el crecimiento de Pediococcus sp. respecto de la levadura de cerveza en un cultivo mixto. El agregado de 0,1 mg/ml de quitosano permitió disminuir la viabilidad de una cepa bacteriana termorresistente, Bacillus megaterium, hasta niveles no detectables. Por otra parte, el agregado de nisina, quitosano y lúpulo aumentó la estabilidad microbiológica durante el almacenamiento de cervezas inoculadas con Lactobacillus plantarum y Pediococcus sp. aislados de mosto de cerveza. La aplicación de campos eléctricos pulsantes (CEP) (3 pulsos de 8kV/cm) aumentó el efecto antimicrobiano de la nisina y del lúpulo, pero no el del quitosano. Los resultados obtenidos indicarían que el uso de antimicrobianos naturales en forma individual o en combinación con CEP puede constituir un procedimiento efectivo para el control de la contaminación bacteriana durante el proceso de elaboración y almacenamiento de la cerveza.

Avaliação de probióticos (Pediococcus acidilactici e Bacillus subtilis) após o desmame e efeitos no desempenho dos leitões / The probiotics (Pediococcus acidilactici and Bacillus subtilis) evaluationafter weaning and effects on the piglets performance

O experimento foi conduzido visando avaliar o uso das bactérias probióticas Pediococcus acidilactici associada ou não ao Bacillus subtilis em rações para leitões recém-desmamados (21 dias) e seus efeito no desempenho até 63 dias de idade. Foram utilizados 210 animais submetidos aos seguintes tratamentos: T1 - ração com Pediococcus acidilactici; T2 - ração com Pediococcus acidilactici + Bacillus subtilis; e T3 - ração isenta de probiótico. Foram avaliados o ganho diário de peso, o consumo diário de ração, a conversão alimentar, a ocorrência de diarréias e a taxa de mortalidade. O delineamento experimental foi em blocos casualizados, com 3 tratamentos e 7 repetições, sendo as médias comparadas pelo teste de Duncan. Observou-se ao final do experimento que animais que receberam o Pediococcus acidilactici associada ou não ao Bacillus subtilis (T1 e T2) apresentaram melhor conversão alimentar (P<0,05) com relação ao grupo de controle. A utilização destas bactérias não determinou ocorrência de diarréias. Os probióticos utilizados podem ser empregados com resultados positivos na conversão alimentar de leitões na fase de creche.

The experiment was conducted with the goal to evaluate the use of rations withPediococcus acidilacticiand Pediococcus acidilactici plus Bacillus subtilis as probiotics to weaned piglets (21 days) and theeffects on the performance until 63 day of age. 210 piglets were submitted to the folowing treatments: T1-ration with Pediococcus acidilactici; T2- ration with Pediococcus acidilactici + Bacillus subtilis; andT3- ration without probiotic. Were evaluated the daily weight gain, daily feed intake and the conversionrate, the dirrohea ocurrence and the mortality rate. The experimental design was a randomized blocks,with 3 treatments and 7 replications, been the means compared by Duncan's Test. At the end of theexperiment the animals that received the ration with Pediococcus acidilactici and the ration withPediococcus acidilactici plus Bacillus subtilis (T1 and T2) presented a better conversion rate (P<0.05)than the control group. The use of these bacterias did not result a diarrohea ocurrence. The probioticsused can be indicated with positive results on conversion rate to piglets in the nursery phase