Effect of Lactic Acid Bacteria Strains on the Growth and Aflatoxin Production Potential of Aspergillus parasiticus, and Their Ability to Bind Aflatoxin B1, Ochratoxin A, and Zearalenone in vitro.

The increased consumption of plant-based foods has intensified the concern related to mycotoxin intoxication. This study aimed to investigate the effect of selected lactic acid bacteria (LAB) strains on the growth of Aspergillus parasiticus NRRL 2999 and its production of aflatoxin (AF). The ability of the heat-killed (100°C for 1 h) LAB strains to bind aflatoxin M1 (AFM1) in milk and aflatoxin B1 (AFB1), ochratoxin A (OTA), and zearalenone (ZEN) in potassium phosphate buffer (PPB) was also evaluated in vitro. Ten LAB strains were tested individually, by inoculating them simultaneously with the fungus or after incubation of the fungus for 24 or 48 h at 25°C. Double layer yeast extract sucrose (YES) agar, de Man Rogosa and Sharpe (MRS) agar, and YES broth were incubated for 7 days at 25°C to follow the development of the fungus. Levilactobacillus spp. 3QB398 and Levilactobacillus brevis 2QB422 strains were able to delay the growth of A. parasiticus in YES broth, even when these strains were inoculated 24 h after the fungus. The inhibitory effect of these LAB strains was confirmed by the reduction of fungus colony size, suggesting dominance of LAB by competition (a Lotka-Voltera effect). The production of AFB1 by A. parasiticus was inhibited when the fungus was inoculated simultaneously with Lactiplantibacillus plantarum 3QB361 or L. plantarum 3QB350. No AFB1 was found when Levilactobacillus spp. 2QB383 was present, even when the LAB was inoculated 48 h after the fungus. In binding studies, seven inactivated LAB strains were able to promote a reduction of at least 50% the level of AFB1, OTA, and ZEN. This reduction varied depending on the pH of the PPB. In milk, however, only two inactivated LAB strains were able to reduce AFM1, with a reduction of 33 and 45% for Levilactobacillus spp. 3QB398 (Levilactobacillus spp.) and L. brevis 2QB422, respectively. Nevertheless, these results clearly indicate the potential of using LAB for mycotoxin reduction.

Microbial interactions during sugar cane must fermentation for bioethanol production: does quorum sensing play a role?

Microbial interactions represent important modulatory role in the dynamics of biological processes. During bioethanol production from sugar cane must, the presence of lactic acid bacteria (LAB) and wild yeasts is inevitable as they originate from the raw material and industrial environment. Increasing the concentration of ethanol, organic acids, and other extracellular metabolites in the fermentation must are revealed as wise strategies for survival by certain microorganisms. Despite this, the co-existence of LAB and yeasts in the fermentation vat and production of compounds such as organic acids and other extracellular metabolites result in reduction in the final yield of the bioethanol production process. In addition to the competition for nutrients, reduction of cellular viability of yeast strain responsible for fermentation, flocculation, biofilm formation, and changes in cell morphology are listed as important factors for reductions in productivity. Although these consequences are scientifically well established, there is still a gap about the physiological and molecular mechanisms governing these interactions. This review aims to discuss the potential occurrence of quorum sensing mechanisms between bacteria (mainly LAB) and yeasts and to highlight how the understanding of such mechanisms can result in very relevant and useful tools to benefit the biofuels industry and other sectors of biotechnology in which bacteria and yeast may co-exist in fermentation processes.

Modeling Growth Kinetic Parameters of Salmonella Enteritidis SE86 on Homemade Mayonnaise Under Isothermal and Nonisothermal Conditions.

During the last decade, a specific strain of Salmonella Enteritidis (named SE86) has been identified as the major etiological agent responsible for salmonellosis in the State of Rio Grande do Sul, Southern Brazil, and the main food vehicle was homemade mayonnaise (HM). This study aimed to model the growth prediction of SE86 on HM under isothermal and nonisothermal conditions. SE86 was inoculated on HM and stored at 7, 10, 15, 20, 25, 30, and 37°C. Growth curves were built by fitting data to the Baranyi's DMFit, generating r(2) values greater than 0.98 for primary models. Secondary model was fitted with Ratkowsky equation, generating r(2) and root mean square error values of 0.99 and 0.016, respectively. Also, the growth of SE86 under nonisothermal conditions simulating abuse temperature during preparation, storage, and serving of HM was studied. Experimental data showed that SE86 did not grow on HM at 7°C for 30 days. At 10°C, no growth was observed until approximately 18 h, and the infective dose (assumed as 10(6) CFU/g) was reached after 8.1 days. However, the same numbers of SE86 were attained after 6 hours at 37°C. Experimental data demonstrated shorter lag times than those generated by ComBase Predictive Models, suggesting that SE86 is very well adapted for growing on HM. SE86 stored under nonisothermal conditions increased population to reach about 10(6) CFU/g after approximately 30 hours of storage. In conclusion, the developed model can be used to predict the growth of SE86 on HM under various temperatures, and considering this pathogen, HM can be produced if safe eggs are used and HM is stored below 7°C.

Characterization of the intestinal microbiota and its interaction with probiotics and health impacts.

The gastrointestinal tract (GIT) is a dynamic microecosystem containing a diversified microbiota of about 500-1000 different microbial species. Humans depend on their intestinal microbiota to carry out vital functions, and thus, equilibrium among intestinal groups of microorganisms is essential. In this review article, the use of traditional and molecular methods is discussed for the characterization of the intestinal microbiota, as well as its interaction with probiotics and their effects on health. An improved knowledge on intestinal microbiota composition and diversity and how changes in this microecosystem can cause or are associated with diseases remains far from being completely understood. Therefore, a better understanding of the GIT microbial populations is crucial, which will certainly contribute to the development of new strategies for the prevention and/or treatment of several diseases. The manipulation of the GIT microbiota by probiotics consumption is an interesting approach to maintain and restore human health.

Avaliação quantitativa do risco de Salmonella e Listeria monocytogenes em vegetais minimamente processados / Quantitative risk assessment of Salmonella and Listeria monocytogenes in minimally processed vegetables

A ocorrência de surtos de doencas associadas aos vegetais minimamente processados (VMP) tem chamado a atenção para a sua segurança microbiológica. A avaliação quantitativa de riscos permite que o impacto das materias-primas e processamento seja avaliado e os resultados obtidos sejam usados para gestão e comunicação do risco. Desta forma, o presente estudo objetivou quantificar o risco de infecções por Salmonella spp. e Listeria monocytogenes a partir do consumo de VMP no Brasil. Um total de quinhentas e doze amostras de VMP foram analisadas e foi possivel enumerar e detectar Salmonella em 0,4% e 0,4% das amostras, respectivamente. L. monocytogenes foi enumerada e detectada em 0,97% e 3,1% das amostras analisadas, respectivamente. Os isolados de Salmonella spp. (n=4) e L. monocytogenes (n=69) foram confirmados por PCR e caracterizados por sorotipagem tradicional. Os isolados de L. monocytogenes foram caracterizados quanto ao ribotipo, resistencia ao cloro, taxa de multiplicação (µ), capacidade de formação de biofilmes e presença de genes de virulência. O sorovar predominante entre Salmonella spp. foi S. Typhimurium. Em relação a L. monocytogenes, observou-se prevalência do sorotipo 4b e do ribogrupo DUP-1038 e presenca de genes de virulência em 100% (inlA) e 97% (inlC e inlJ) dos isolados. A maioria dos isolados de L. monocytogenes foi resistente a exposição a 125 ppm de cloro livre, e todos foram capazes de aderir ao aco inox, atingindo concentracoes acima de 4 log UFC/cm2. Testes-desafio foram conduzidos para determinar o potencial de multiplicação (δ) de cepas de Salmonella e L. monocytogenes em nove diferentes tipos of VMPs armazenados a 7°C e 15°C por 6 dias. O armazenamento a 15°C por 6 dias resultou nos maiores aumentos nas populações de L. monocytogenes em couve picada (δ= 3,34) e rúcula ((δ= 3,22), enquanto para Salmonella, as maiores populações foram observadas em rúcula (δ= 4,05) e escarola (δ= 2,80). Testes-desafios posteriores indicaram que a multiplicação dos dois patógenos em VMP foi mais pronunciada quando os mesmos foram embalados sob atmosfera modificada em comparação a embalagem em filmes perfurados. Modelos preditivos primários e secundários descrevendo a taxa de multiplicação e tempo de lag de Salmonella spp. e L. monocytogenes em VMP em função da temperatura de armazenamento (7, 10, 15, 20, 25 e 30°C) foram gerados. Verificou-se que os modelos gerados apresentaram a precisão necessária e foram adequados para modelagem da multiplicação dos dois patógenos em VMP. Os modelos de avaliação quantitativa de risco (AQR) foram construidos para determinar a probabilidade de infecção por Salmonella spp. e L. monocytogenes devido ao consumo de VMPs. Os modelos construidos com base nos dados levantados da literatura indicaram risco de infecção por Salmonella spp. e L. monocytogenes de 8.66 x 10-3 e 1.87 x 10-8, respectivamente, sendo necessário que medidas de mitigação do risco sejam adotadas

The occurrence of foodborne disease outbreaks linked to minimally processed vegetables (MPV) is concerning industries, consumers and governments worldwide. Quantitative risk assessments can estimate the impact of raw materials and processing practices and these estimates are used for risk management and risk communication. This study aimed at quantifying the risks of infection by Salmonella spp. and Listeria monocytogenes due to consumption of MPV in Brazil. A total of five hundred and twelve samples of MPV were analyzed and Salmonella was detected and enumerated in 0.4% and 0.4% of the samples, respectively. L. monocytogenes was enumerated and detected in 0.97% and 3.1% of the samples analyzed, respectively. Isolates of Salmonella spp. (n=4) and L. monocytogenes (n=69) were confirmed through PCR and characterized by traditional serotyping. The isolates of L. monocytogenes were characterized for their ribotype, resistance to chlorine, growth rate, (µ) and ability to form biofilms and presence of virulence factors. Among Salmonella spp., S. Thyphimurium was the most prevalent serovar. Among L. monocytogenes, prevalence of serotype 4b and ribotype DUP-1038 was observed. Virulence gene inlA was present in 100% of the isolates, and genes inlC and inlJ in 97%. The majority of L. monocytogenes isolates were resistant to up to 125 ppm of free chlorine and all isolates were able to attach to stainless steel coupons, reaching populations of up to 4 log10 CFU/cm2. Challenge tests were carried out to determine the growth potential (δ) of Salmonella and L. monocytogenes in nine types of MPV stored at 7°C and 15°C for 6 days. The storage of MPV at 15°C for 6 days resulted in the greatest increases in L. monocytogenes populations in shredded collard green (δ= 3.34) and arugula (δ= 3.22), whereas for Salmonella, the highest populations were found in arugula (δ= 4.05) and escarole (δ= 2.80). Further challenge tests indicated that multiplication of both pathogens in MPV was more pronounced when these products were packaged under modified atmosphere in comparison to packaging in perforated films. Primary and secondary predictive models describing the growth rate and lag time of Salmonella and L. monocytogenes in MPV as a function of storage temperature (7-30°C) were generated. The generated models were accurate and suitable for modeling the growth of pathogens in MPVs. Quantitative risk assessment (QRA) models were built to determine the probability of infection by Salmonella and L. monocytogenes due to consumption of MPVs. The models built using data available in the literature indicated that the risks of infection by these pathogens were 8.66 x 10-3 and 1.87 x 10-8, respectively, evidencing the need for adoption of risk mitigation measures

Use of a logistic model to assess spoilage by Byssochlamys fulva in clarified apple juice.

The percentage P (%) of spoiled bottles (n=40) of clarified apple juice due to Byssochlamys fulva, was modeled by using a logistic model: P = P(max)/1 + exp (k(tau-t)) where P(max) (%) the maximum percentage of spoiled bottles, k (h(-1)) a slope parameter and tau (h) the time for P=P(max)/2. Bottles of pasteurized apple juice were inoculated with B. fulva IOC 4518 ascospores for low and high initial loads, 4.8+/-2.3 ascospores/100mL and 19.3+/-4.6 ascospores/100mL respectively and incubated at 21 degrees C and 30 degrees C. P(max) was not significantly different from 100% except for a low initial load at 21 degrees C. Model parameters were estimated with a good accuracy, RMSE in the range 3.89-7.50. Then the model was used to determine the time for 10% bottles spoiled, t(10%). This time was greater at low initial loads, 57.4 and 104 h at 30 and 21 degrees C respectively, than at high initial loads 23.9 and 75.1h at 30 and 21 degrees C respectively. This study demonstrated that even at a very low initial contamination, clarified apple juice can be easily spoiled by B. fulva highlighting the importance of controlling critical control steps of fruit juice processing (i.e., fruit washing, juice filtration and pasteurization).

Review: Microbiological quality and safety of fruit juices--past, present and future perspectives.

In this review paper, several aspects of fruit juice microbiology, from past to future perspectives, are considered. An overview of the most relevant outbreaks involving foodborne pathogens and spoilage microorganisms associated with fruit juices is provided. One of the sections provides data on the sources of fruit juice contamination, followed by perspectives on preservation methods. Furthermore, considerations on the role of international guidelines about exotic fruit juices in respect to public health, and of the microbiological status of fruit juices used as food/beverage ingredients are discussed. Issues and challenges highlight how the microbiology of fruit juices has evolved over the years, when aspects of stability or microbiological safety are under consideration.

High prevalence, low counts and uncommon serotypes of Listeria monocytogenes in linguiça, a Brazilian fresh pork sausage.

Linguiça is a highly popular and appreciated pork product in Brazil, frequently consumed undercooked. Aiming at collection of data for a future risk assessment, this study evaluated the prevalence and counts of Listeria monocytogenes in linguiça samples collected at retail level in Sao Paulo, SP, Brazil. ISO methods were used for detection and enumeration of the pathogen (11290-1 and 11290-2, respectively). Isolates were submitted to Simplex-PCR for hlyA gene and those with biochemical features of L. monocytogenes and hlyA positive were serotyped using a Multiplex PCR. Ninety percent of the samples were positive for Listeria spp., and L. monocytogenes was detected in 42% of the samples, with counts below 10(2)CFU/g in all samples. A prevalence of uncommon serotypes 4a and 4c was observed.

Irradiação e a segurança e qualidade microbiológica dos alimentos / Irradiation and safety and microbiological quality of food

A OMS (Organização Mundial de Saúde) estima que a perda mundial de alimentos seja de um quarto a um terço da produção, sendo as pragas, bactérias, fungos e enzimas os principais agentes responsáveis. Também segundo a OMS, 70 por cento das 3,2 milhões de mortes anuais de crianças com menos de 5 anos são decorrentes de doenças provocadas por patógenos veiculados por alimentos. Para reduzir as perdas por deterioração dos alimentos e, também, fornecer alimentos seguros ao consumo da população, o homem lança mão dos métodos de conservação. Um método a ser considerado é a irradiação, que pode ser aplicada aos alimentos com diversos objetivos. No presente artigo é realizada uma revisão das principais e potenciais aplicações da irradiação dos alimentos, visando a garantia de sua qualidade e segurança.

Efeito da adição de dicloran ao diluente, para enumeração de fungos em alimentos desidratados utilizando-se o sistema petrifilm para bolores e leveduras / Effect of the addition of dicloran to the diluent, for enumeration of fungi in sustenances dehydrated utilizing itself the system petrifilm for fungi and yeasts

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.

The yeast and mold enumeration of foods is indicative of poor hygienical conditions in the processing or raw materials of bad quality. In dehydrated foods, the xerophilic fungi are the major responsible of deterioration. Several techniques and culture media have been used for its enumeration, being agar DG-18 recommended for foods with low water activity. Ten differents food samples were divided into five subsamples, totalizing 50 samples. The following treatments were evaluaied: PetrifiIm (control), PetrifiIm (with dicloran) and DG-18 (control). The results of the statistical analysis allow to conclude that it does not have significant difference to the 5% level between the evaluated treatments. The occurrence of spread colonies, seems not to be associated to a type of food, but with samples of one determined food. When high dilutions were used, spread colonies weren't present, not affecting, therefore, the Petrifilm Yeast and Mold counts.

Efeito da adição de dicloran ao diluente, para enumeração de fungos em alimentos desidratados utilizando-se o sistema petrifilm para bolores e leveduras / Effect of the addition of dicloran to the diluent, for enumeration of fungi in sustenances dehydrated utilizing itself the system petrifilm for fungi and yeasts

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.

Comparação entre os métodos rápidos Simplate TPC-CI e Petrifilm AC e os métodos convencionais de contagem em placas, para a enumeração de aeróbios mesófilos em sorvetes / Comparation between Simplate TPC-CI and Petrifilm AC and standard plate count for the mesophilic aerobic count in ice-cream

A contagem de aeróbios mesófilos ou contagem padrão em placas em um produto alimentício reflete a qualidade da matéria-prima, bem como as condições de processamento, manuseio e estocagem. O método de contagem em placas tradicional requer 48h de incubação para a posteriro leitura dos resultados. Comparou-se dois métodos que parecem ser uma boa alternativa para a contagem padrão em placas: Simplate TPC-CI e Petrifilm AC. Também avaliou-se a capacidade inibitória do 2,3,5 cloreto de trifeniltetrazólio quando adicionado ao Agar Plate Count. Este corante é incolor na forma oxidada e vermelho quando reduzido pelos microrganismos, devido a formação de formazano. O coeficiente de correlação obtido, através de estudos conduzidos com 60 amostras de sorvetes, entre 0,866-0,979 indicou uma equivalente sensibilidade dos métodos testados. Somente a contagem padrão em placas com TTC diferiu significativamente da contagem padrão em placas.