In Vitro Antimicrobial Activity and Aggregation Abilities of Probiotic Lactobacillus casei and Lactobacillus salivarius Against Oral Pathogens

ABSTRACT@#The antagonistic effect of probiotics against oral pathogens merits exploration because these bacteria are beneficial to the host’s health. The antimicrobial activity of two probiotic strains, Lactobacillus casei and Lactobacillus salivarius, as well as L. casei and L. salivarius combination (1:1), was investigated against Streptococcus mutans, Streptococcus sobrinus, Candida albicans, Candida glabrata and Candida tropicalis using agar-well diffusion, auto-aggregation and coaggregation assays. L. salivarius cell-free supernatant (CFS) alone exhibited greater inhibitory effect against Streptococci spp. compared to L. casei CFS alone and the combination. However, no inhibition was observed for Candida spp. L. salivarius alone exhibited significantly stronger auto-aggregation than L. casei alone (p ≤ 0.05) and L. casei and L. salivarius combination. L. salivarius exhibited strong coaggregation ability with Candida spp., followed by Streptococci spp. while L. casei exhibited coaggregation only with Streptococci spp. However, L. casei and L. salivarius combination did not display any coaggregation with all strains. L. salivarius alone exhibited a stronger antagonistic effect on the tested organisms than L. casei alone or in combination. Based on the results, both probiotic strains showed good antimicrobial activities against oral pathogens and should be further studied for their human health benefits.

Transcriptomic profiling of substrate-dependent autoaggregation in Pseudomonas putida CP1

Aims@#Pseudomonas putida CP1 is an interesting environmental isolate which exhibits substrate-dependent autoaggregation when the organism was grown on 0.5% (w/v) fructose. Autoaggregation is a process of a single bacterial species to develop clumps of cells during a substrate stress. This study was carried out to investigate the genetic changes in the bacterium during aggregate formation. @*Methodology and results@#P. putida CP1 was grown on 0.5% (w/v) fructose in batch culture at 30 °C and 150 rpm. The removal of fructose from the medium corresponded with aggregation of the cells which started after 8 h incubation. Microarray gene expression profiling using a P. putida KT2440 Genome Oligonucleotide Array (Progenika, Spain) showed that 838 genes involved in metabolism and adaptation were differentially expressed in P. putida CP1. Global transcriptomic profiling studies showed that P. putida CP1 growing on fructose resulted in the induction of genes encoding for proteins mainly involved in protein translation, ABC transporters, oxidative phosphorylation and two-component systems (TCS). Novel genes, associated with autoaggregation, were identified using transcriptomic analysis involved in ABC transporter, TCS, flagella assembly and lipopolysaccharide biosynthesis. It was also associated with the up-regulation of genes involved in the flagellar assembly including the fliE gene which encodes for the flagellar hook-basal body protein. @*Conclusion, significance and impact of study@#The identification of new genes involved in autoaggregation formation is important to understand the molecular basis of strain variation and the mechanisms implicated in cell-cell communication.

Influences of extracellular polymeric substances (EPS) for autoaggregation of Pseudomonas putida CP1 during growth on mono-chlorophenol

Aims: Pseudomonas putida CP1 exhibits substrate-dependent autoaggregation during the degradation of 100 ppm 2- chlorophenol, 100 ppm 3-chlorophenol and 200 ppm 4-chlorophenol. This study discussed the production of extracellular polymeric substances (EPS) by the organism for the formation of aggregates. Methodology and results: Aggregation was accompanied by the production of extracellular polymeric substances (EPS). The extent of EPS production and the size of the aggregates increased with increasing stress as did the aggregation index and the hydrophobicity of the cells. A biochemical analysis of the EPS showed that the main constituents were carbohydrate (40% w/v) and protein (50% w/v) together with lower levels of DNA (<10% w/v). Conclusion, significance and impact study: Given that the aggregated form of the bacterium has shown potential for use in bioaugmentation, an in-depth understanding of the phenomenon could enhance the use of this organism in biological wastewater treatment systems.

Adhesion, Autoaggregation and Hydrophobicity of Six Lactobacillus Strains.

Aims: The aim of this study was to assess probiotic attributes such as adhesion, auto aggregation, hydrophobicity and antibacterial activity of Lactobacillus strains from dairy products. Methodology: In this study, the autoaggregation, coaggregation, hydrophobicity and adhering abilities and antimicrobial activities of six Lactobacillus strains belonging to different species were assessed. Hydrophobicity was determined by bacterial adherence to hydrocarbons, xylene, n-hexadecane and chloroform. Results: The percentage of hydrophobicity of the strains range from 29.5% to 77.4% as measured by the described test. The autoaggregation among Lactobacillus strains range from 15.8% to 63.1%, while coaggregation range from 18.6% to 55.1%. Adhesion of the tested strains to buccal epithelial cells range from 8.0% to 50%. The tested Lactobacillus strains demonstrated variable inhibitory activity against pathogenic bacteria. Conclusion: Our findings indicated that one Lactobacillus strain expressed broad antibacterial activities against a group of bacterial pathogens and along 2 other strains exhibited ability to adhere to epithelial cells as shown by aggregation, coaggregation and hydrophobicity, indicating that such isolates can be good candidates for probiotic use.

Evaluation of adhesive properties of presumptive probiotic Lactobacillus plantarum strains / Avaliação das propriedades de adesão de presumíveis estirpes probióticas de Lactobacillus plantarum

Thirty-two strains of Lactobacillus plantarum UFLA SAU from pork sausages, pre-selected for some features for probiotic application, were utilized in this study to evaluate their adhesive properties and compare the results against the three pathogens also tested. Strains were tested for autoaggregation and coaggregation capacity and Microbial Adhesion To Solvents (MATS) at the time intervals of 0, 1, 2, 3 and 4 h. Our findings revealed that UFLA SAU strains have a high autoaggregative capacity and coaggregative ability with pathogens, especially Listeria monocytogenes. In relation to adhesion to solvents, in general, L. plantarum strains showed hydrophilic cell surface properties and an important electron donor and basic character. Adhesive properties were markedly separated for the strains under study by Principal Component Analysis software. UFLA SAU 132, 226 and 87 were differentiated by autoaggregation ability. UFLA SAU 11 and Listeria monocytogenes were characterized by adhesion to solvents. UFLA SAU 14, 18 and 172 showed high coaggregation with Escherichia coli, Salmonella Typhi and Listeria monocytogenes. In comparison to the pathogens tested, many UFLA SAU strains presented higher adhesive capacity. These tests should be used for screening and identifying potentially adherent microorganisms. Adhesive properties are important features for the choice of probiotic strains and confer various applications, such as in the pharmaceutical (therapeutic or prophylactic) and food (functional foods) industries.

Trinta e duas estirpes de linguiça suína, Lactobacillus plantarum UFLA SAU, pré-selecionadas com algumas características para aplicação probiótica, foram utilizadas neste estudo para avaliar suas propriedades adesivas e comparar os resultados com três patógenos também testados. As estirpes foram testadas para autoagregação, coagregação e capacidade de adesão microbiana aos solventes (MATS) nos tempos de 0, 1, 2, 3 e 4 h. Nossos resultados revelaram que estirpes UFLA SAU apresentam alta capacidade autoagregativa e coagregativa com patógenos, especialmente com Listeria monocytogenes. Em relação à adesão aos solventes, de um modo geral, as estirpes de L. plantarum mostraram propriedades hidrofílicas de superfície celular e um importante caráter básico e elétron doador. Propriedades adesivas foram marcadamente separadas para as estirpes em estudo através da Análise de Componentes Principais. UFLA SAU 132, 226 e 87 foram diferenciadas pela capacidade de autoagregação. UFLA SAU 11 e Listeria monocytogenes foram caracterizadas por adesão aos solventes. UFLA SAU 14, 18 e 172 apresentaram coagregação com Escherichia coli, Salmonella Typhi e Listeria monocytogenes. Em comparação aos patógenos testados, muitas estirpes UFLA SAU apresentaram maior capacidade adesiva. Estes testes podem ser úteis para a triagem e identificação de micro-organismos potencialmente aderentes. Propriedades adesivas são importantes características para a escolha de estirpes probióticas e conferem várias aplicações, tais como nas indústrias: farmacêutica (terapêutico ou profilático) e de alimentos (alimentos funcionais).