Avaliação in vitro da atividade inibitória de Lactobacillus spp., isolados do inglúvio e cecos de aves sobre Salmonella

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immunological evaluation of the intestinal mucosa of broiler chicks treated with Lactobacillus Spp. and challenged with Salmonella Enteritidis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transference in vitro of the resistance to the antimicrobials between Escherichia coli, Lactobacillus spp. and Salmonella enteritidis isolated from chickens

O objetivo deste trabalho foi verificar a possibilidade de transferência de resistência aos antimicrobianos entre bactérias normais da microbiota de frangos e Salmonella Enteritidis. Utilizamos amostras de Lactobacillus spp. (L. spp.), Salmonella Enteritidis (SE) e Escherichia coli (E. coli) previamente isolados de frangos, selecionados após prova de sensibilidade antimicrobiana in vitro conforme metodologia padrão (Comitê Nacional para Padrões Clínicos de Laboratório). Utilizamos aqueles com resistência e sensibilidade aos antimicrobianos indutores, chamados de bactérias doadoras e receptoras, respectivamente. Os antimicrobianos indutores foram utilizados para estimular a transferência de resistência aos antimicrobianos entre as bactérias. A possibilidade de transferência foi verificada da E. coli resistente para a SE e L. spp. Também foi verificada a transferência de uma amostra de L. spp resistente aos antimicrobianos indutores para a SE. Só foi possível verificar a transferência da resistência aos antimicrobianos indutores quando a bactéria doadora foi a E. coli e a bactéria receptora foi a SE. No presente estudo concluímos que a transferência de resistência aos antimicrobianos entre bactérias é possível, mas nem todas as bactérias participam desse evento, não transmitindo e nem adquirindo esta resistência.

Comparação entre método bioquímico e reação em cadeia de polimerase para identificação de Lactobacillus spp., isolados de aves

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of in vitro and in vivo adhesion and immunomodulatory effect of Lactobacillus species strains isolated from chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of sample type and collection method on Streptococcus mutans and Lactobacillus spp. counts in the oral cavity

Objectives: This study compared three methods of Streptococcus mutans and Lactobacillus spp. detection in the oral cavity: saliva swab (SS)-sample of stimulated saliva collected with swab; whole saliva (WS)-sample of 2 ml of stimulated saliva; and the dental plaque method (DP)-plaque sample of all dental surfaces.Methods: Thirty children were included in this study. In the first 15 children, the SS and WS methods were carried out before the dental plaque collection, and in the following 15, the sequence was inverted to evaluate possible interference of the methods sequence. The samples were diluted and inoculated in SB20 and Rogosa agar, respectively for S. mutans and Lactobacillus spp., at 37 degrees C for 48 h.Results: the results (cfu/mL) of S. mutans were analysed by the statistical Friedman's test. The levels of Lactobacillus spp. were analysed by descriptive statistics due to the high proportion of zero counts in the culture. In the first sequence of methods, the number of S. mutans counted for the SS method was inferior to DP and WS (P < 0.05), and the results for the WS and DP methods were similar. The detection of Lactobacillus spp. was observed just by the WS (100 %) and SS (14.3 %) methods. However, in the second experimental set the number of S. mutans detected by the DP method was similar to those of the SS and WS, however, the WS method showed higher values than SS (P < 0.05). A greater number of Lactobacillus spp. was detected by the WS method (100 %), followed by SS (55.5 %) and DP (33.3 %).Conclusions: the dental plaque collection and the sample of stimulated whole saliva presented similar results in the S. mutans count. The most suitable method to detect the Lactobacillus spp. level in the oral cavity is the stimulated whole saliva method. (c) 2004 Elsevier Ltd. All rights reserved.

Inhibitory effect of essential oils against Lactobacillus rhamnosus and starter culture in fermented milk during its shelf-life period

The use of essential oils in foods has attracted great interest, due to their antagonistic action against pathogenic microorganisms. However, this action is undesirable for probiotic foods, as products containing Lactobacillus rhamnosus. The aim of the present study was to measure the sensitivity profile of L. rhamnosus and a yogurt starter culture in fermented milk, upon addition of increasing concentrations of cinnamon, clove and mint essential oils. Essential oils were prepared by steam distillation, and chemically characterised by gas chromatography-mass spectrometry (GC-MS) and determination of density. Survival curves were obtained from counts of L. rhamnosus and the starter culture (alone and in combination), upon addition of 0.04% essential oils. In parallel, titratable acidity was monitored over 28 experimental days. Minimum inhibitory concentration values, obtained using the microdilution method in Brain Heart Infusion medium, were 0.025, 0.2 and 0.4% for cinnamon, clove and mint essential oils, respectively. Cinnamon essential oil had the highest antimicrobial activity, especially against the starter culture, interfering with lactic acid production. Although viable cell counts of L. rhamnosus were lower following treatment with all 3 essential oils, relative to controls, these results were not statistically significant; in addition, cell counts remained greater than the minimum count of 10(8)CFU/mL required for a product to be considered a probiotic. Thus, although use of cinnamon essential oil in yogurt makes starter culture fermentation unfeasible, it does not prevent the application of L. rhamnosus to probiotic fermented milk. Furthermore, clove and mint essential oil caused sublethal stress to L. rhamnosus.

Cell enumeration and visualisation by transmission electron microscopy of Lactobacillus rhamnosus treated with cinnamon (Cinnamomum zeylanicum B.) essential oil

The use of essential oils (EOs) in functional foods containing probiotic microorganisms must consider the antimicrobial activity of these oils against beneficial bacteria such as Lactobacillus rhamnosus. This study aimed to evaluate the sensitivity of L. rhamnosus cultures treated with cinnamon EO through viable cell counts and visualisation by transmission electron microscopy. Cinnamon EO at a concentration of 0.04% had a bacteriostatic activity after 2 h of incubation. Although slight alterations were detected in the cell structure, this concentration was considered to be bactericidal, since it led to a significant reduction in cell numbers after 24 h. on the other hand, cinnamon EO at a 1.00% concentration decreased cell counts by 3 log units after 2 h incubation and no viable cell count was detected after 24 h. Transmission electron microscopy indicated that cells treated with 1.00% cinnamon EO were severely damaged and presented cell membrane disruption and cytoplasmic leakage.

Lactic acid production by new Lactobacillus plantarum LMISM6 grown in molasses: optimization of medium composition

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Improvement of L(+)-lactic acid production from cassava wastewater by Lactobacillus rhamnosus B 103

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Response surface optimization of D(-)-lactic acid production by Lactobacillus SMI8 using corn steep liquor and yeast autolysate as an alternative nitrogen source

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Floculação de leveduras por Lactobacillus fermentum em processos industriais de fermentação alcoólica avaliada por técnica fotométrica

Na produção de álcool por fermentação com leveduras, a floculação manifesta-se como um mecanismo natural de agregação de células. Essa condição pode ser induzida por vários fatores, entre eles, a interação entre bactérias floculentas como Lactobacillus fermentum e as leveduras. Esse fato torna-se prejudicial para o processo, pois tanto nas unidades que se utilizam do sistema de recuperação de células por centrifugação, como nas que não o utilizam, ocorrem perdas excessivas de fermento, em conseqüência dos problemas operacionais decorrentes da floculação, comprometendo seriamente o desempenho industrial. No presente trabalho, avaliou-se a floculação em vinho proveniente de fermentação experimental, sob duas condições de pH de fermento tratado utilizadas como inóculo e temperaturas de fermentação, não se observando diferenças significativas entre elas. Com este estudo, pôde-se ainda avaliar a capacidade de dispersão dos flocos em três condições de pH no tratamento do fermento em fase industrial, mostrando diferenças altamente significativas entre elas. A maior capacidade de dispersão no tratamento do fermento é desejável para o controle da floculação industrial, permitindo a sua centrifugação, com conseqüente separação das bactérias contaminantes do fermento. Essas constatações tornaram-se possíveis pelo emprego da técnica usual de determinação da floculação por espectrofotometria, modificada pela desfloculação prévia das amostras de vinho e fermento, o que conferiu maior estabilidade nas leituras.