Consortium Building For PEM MFC Using Synthetic Media As Substrate

Microbial production of electricity is an important form of bioenergy since Microbial Fuel cells (MFC) offer the possibility of extracting electric current from a wide range of organic wastes and renewable biomass. Factors affecting the MFC operational effectiveness are the MFC design and the bacterial metabolism and electron transfer. The purpose of this study is to identify species which are responsible for electricity generation so as to build a suitable consortium and to investigate the relative efficiencies between the microbial consortiums. Enrichment by repeated transfer of a bacterial consortium harvested from the anode compartment of a MFC with synthetic media as a substrate increased the output from an initial level of 34 mA to a maximal level of 363 mA. Scanning electron microscope image indicated the enhanced microbial biofilm deposition over the electrode which were not initially detected in the community

In vitro and in vivo selection of potentially probiotic lactobacilli from Nocellara del Belice table olives

Table olives are increasingly recognized as a vehicle as well as a source of probiotic bacteria, especially those fermented with traditional procedures based on the activity of indigenous microbial consortia, originating from local environments. In the present study, we report characterization at the species level of 49 Lactic Acid Bacteria (LAB) strains deriving from Nocellara del Belice table olives fermented with the Spanish or Castelvetrano methods, recently isolated in our previous work. Ribosomal 16S DNA analysis allowed identification of 4 Enterococcus gallinarum, 3 E. casseliflavus, 14 Leuconostoc mesenteroides, 19 Lactobacillus pentosus, 7 L. coryniformis, and 2 L. oligofermentans. The L. pentosus and L. coryniformis strains were subjected to further screening to evaluate their probiotic potential, using a combination of in vitro and in vivo approaches. The majority of them showed high survival rates under in vitro simulated gastro-intestinal conditions, and positive antimicrobial activity against Salmonella enterica serovar Typhimurium, Listeria monocytogenes and enterotoxigenic Escherichia coli (ETEC) pathogens. Evaluation of antibiotic resistance to ampicillin, tetracycline, chloramphenicol, or erythromycin was also performed for all selected strains. Three L. coryniformis strains were selected as very good performers in the initial in vitro testing screens, they were antibiotic susceptible, as well as capable of inhibiting pathogen growth in vitro. Parallel screening employing the simplified model organism Caenorhabditis elegans, fed the Lactobacillus strains as a food source, revealed that one L. pentosus and one L. coryniformis strains significantly induced prolongevity effects and protection from pathogen-mediated infection. Moreover, both strains displayed adhesion to human intestinal epithelial Caco-2 cells and were able to outcompete foodborne pathogens for cell adhesion. Overall, these results are suggestive of beneficial features for novel LAB strains, which renders them promising candidates as starters for the manufacturing of fermented table olives with probiotic added value

vanA in Enterococcus faecium, Enterococcus faecalis, and Enterococcus casseliflavus detected in French cattle.

The goal of this study was to assess the presence of enterococci species presenting van-mediated glycopeptide resistance in French cattle. Fecal samples were collected from healthy and sick animals, and enterococci were screened for vancomycin resistance. Vancomycin resistance was principally encountered in Enterococcus gallinarum and Enterococcus casseliflavus strains. However, glycopeptide resistance was detected in three different species of enterococci (E. faecalis, E. faecium, and E. casseliflavus). Molecular characterization of the genetic support proved that they all presented the prototypic VanA element. Interestingly, the E. casseliflavus strain displayed a remarkable VanB phenotype/vanA-vanC genotype. Transferability, associated resistances, and factors of vanA cotransfer were sought. This study proved that acquired vanA genes can still be detected in food-producing animals more than a decade after the avoparcin ban. Indeed, calves, which are recurrently exposed to antibiotics in France, may allow the re-emergence of glycopeptide resistance through coselection factors, and this might potentially be concerning for human health

Characterization of a bacteriocin produced by enterococcus gallinarum CRL 1826 Isolated from captive bullfrog: evaluation of its mode of action against Listeria monocytogenes and gram-negatives

Enterococcus gallinarum CRL 1826 isolated from an American bullfrog (Lithobates catesbeianus) skin inhibits the growth of Citrobacter freundii, Pseudomonas aeruginosa (bullfrog pathogens) and Listeria monocytogenes by a synergistic effect between organic acids and a bacteriocin-like molecule. This bacteriocin, named enterocin CRL 1826, showed a proteinaceous nature, heat stability and polar characteristics. Its production followed kinetics of primary metabolites synthesis reaching a maximum of 61,400 AU/mL. The minimum inhibitory and minimumbactericidal concentrations were 2,640 and 5,280 AU/mL, respectively, against L. monocytogenes. The addition of 120,000 AU/mL of enterocin to growing L. monocytogenes and Gram-negative (P. aeruginosa and C. freundii) bacteria showed bactericidal and bacteriostatic effects, respectively. However, enterocin derived-peptides had bactericidal effect only against Gram-negatives.Enterocin produced cell envelope damages and efflux of citosolic content on L. monocytogenes, while enterocin derived-peptides showed granulation and contraction of cytoplasm material on P. aeruginosa and increase in theperiplasmic space and empty cells appearance on C. freundii.Enterocin CRL 1826 is the first bacteriocin described for E. gallinarum from raniculture. It could be used as a biopreservative while the derived-peptides represent an alternative to control multi-drug resistant Gram-negatives.The antimicrobial spectrum and the stability of enterocin and its derived-peptides indicate that they could be applied in different biotechnological areas.Fil: Montel Mendoza, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; Argentin

Membership and behavior of ultra-low-diversity pathogen communities present in the gut of humans during prolonged critical illness.

UnlabelledWe analyzed the 16S rRNA amplicon composition in fecal samples of selected patients during their prolonged stay in an intensive care unit (ICU) and observed the emergence of ultra-low-diversity communities (1 to 4 bacterial taxa) in 30% of the patients. Bacteria associated with the genera Enterococcus and Staphylococcus and the family Enterobacteriaceae comprised the majority of these communities. The composition of cultured species from stool samples correlated to the 16S rRNA analysis and additionally revealed the emergence of Candida albicans and Candida glabrata in ~75% of cases. Four of 14 ICU patients harbored 2-member pathogen communities consisting of one Candida taxon and one bacterial taxon. Bacterial members displayed a high degree of resistance to multiple antibiotics. The virulence potential of the 2-member communities was examined in C. elegans during nutrient deprivation and exposure to opioids in order to mimic local conditions in the gut during critical illness. Under conditions of nutrient deprivation, the bacterial members attenuated the virulence of fungal members, leading to a "commensal lifestyle." However, exposure to opioids led to a breakdown in this commensalism in 2 of the ultra-low-diversity communities. Application of a novel antivirulence agent (phosphate-polyethylene glycol [Pi-PEG]) that creates local phosphate abundance prevented opioid-induced virulence among these pathogen communities, thus rescuing the commensal lifestyle. To conclude, the gut microflora in critically ill patients can consist of ultra-low-diversity communities of multidrug-resistant pathogenic microbes. Local environmental conditions in gut may direct pathogen communities to adapt to either a commensal style or a pathogenic style.ImportanceDuring critical illness, the normal gut microbiota becomes disrupted in response to host physiologic stress and antibiotic treatment. Here we demonstrate that the community structure of the gut microbiota during prolonged critical illness is dramatically changed such that in many cases only two-member pathogen communities remain. Most of these ultra-low-membership communities display low virulence when grouped together (i.e., a commensal lifestyle); individually, however, they can express highly harmful behaviors (i.e., a pathogenic lifestyle). The commensal lifestyle of the whole community can be shifted to a pathogenic one in response to host factors such as opioids that are released during physiologic stress and critical illness. This shift can be prevented by using compounds such as Pi-PEG15-20 that interrupt bacterial virulence expression. Taking the data together, this report characterizes the plasticity seen with respect to the choice between a commensal lifestyle and a pathogenic lifestyle among ultra-low-diversity pathogen communities that predominate in the gut during critical illness and offers novel strategies for prevention of sepsis

Utilization of tmRNA sequences for bacterial identification

In recent years, molecular approaches based on nucleotide sequences of ribosomal RNA (rRNA) have become widely used tools for identification of bacteria [1-4]. The high degree of evolutionary conservation makes 16S and 23S rRNA molecules very suitable for phylogenetic studies above the species level [3-5]. More than 16,000 sequences of 16S rRNA are presently available in public databases [4,6]. The 16S rRNA sequences are commonly used to design fluorescently labeled oligonucleotide probes. Fluorescence in situ hybridization (FISH) with these probes followed by observation with epifluorescence microscopy allows the identification of a specific microorganism in a mixture with other bacteria [2-4]. By shifting probe target sites from conservative to increasingly variable regions of rRNA, it is possible to adjust the probe specificity from kingdom to species level. Nevertheless, 16S rRNA sequences of closely related strains, subspecies, or even of different species are often identical and therefore can not be used as differentiating markers [3]. Another restriction concerns the accessibility of target sites to the probe in FISH experiments. The presence of secondary structures, or protection of rRNA segments by ribosomal proteins in fixed cells can limit the choice of variable regions as in situ targets for oligonucleotide probes [7,8]. One way to overcome the limitations of in situ identification of bacteria is to use molecules other than rRNA for phylogenetic identification of bacteria, for which nucleotide sequences would be sufficiently divergent to design species specific probes, and which would be more accessible to oligonucleotide probes. For this purpose we investigated the possibility of using tmRNA (also known as 10Sa RNA; [9-11]). This molecule was discovered in E. coli and described as small stable RNA, present at ~1,000 copies per cell [9,11]. The high copy number is an important prerequisite for FISH, which works best with naturally amplified target molecules. In E. coli, tmRNA is encoded by the ssrA gene, is 363 nucleotides long and has properties of tRNA and mRNA [12,13]. tmRNA was shown to be involved in the degradation of truncated proteins: the tmRNA associates with ribosomes stalled on mRNAs lacking stop codons, finally resulting in the addition of a C-terminal peptide tag to the truncated protein. The peptide tag directs the abnormal protein to proteolysis [14,15]. 165 tmRNA sequences have so far (August 2001; The tmRNA Website: http://www.indiana.edu/~tmrna/) been determined [16,17]. The tmRNA is likely to be present in all bacteria and has also been found in algae chloroplasts, the cyanelle of Cyanophora paradoxa and the mitochondrion of the flagellate Reclinomonas americana[10,17,18]

Genomic comparative analysis of the environmental Enterococcus mundtii against enterococcal representative species

Background Enterococcus mundtii is a yellow-pigmented microorganism rarely found in human infections. The draft genome sequence of E. mundtii was recently announced. Its genome encodes at least 2,589 genes and 57 RNAs, and 4 putative genomic islands have been detected. The objective of this study was to compare the genetic content of E. mundtii with respect to other enterococcal species and, more specifically, to identify genes coding for putative virulence traits present in enterococcal opportunistic pathogens. Results An in-depth mining of the annotated genome was performed in order to uncover the unique properties of this microorganism, which allowed us to detect a gene encoding the antimicrobial peptide mundticin among other relevant features. Moreover, in this study a comparative genomic analysis against commensal and pathogenic enterococcal species, for which genomic sequences have been released, was conducted for the first time. Furthermore, our study reveals significant similarities in gene content between this environmental isolate and the selected enterococci strains (sharing an “enterococcal gene core” of 805 CDS), which contributes to understand the persistence of this genus in different niches and also improves our knowledge about the genetics of this diverse group of microorganisms that includes environmental, commensal and opportunistic pathogens. Conclusion Although E. mundtii CRL1656 is phylogenetically closer to E. faecium, frequently responsible of nosocomial infections, this strain does not encode the most relevant relevant virulence factors found in the enterococcal clinical isolates and bioinformatic predictions indicate that it possesses the lowest number of putative pathogenic genes among the most representative enterococcal species. Accordingly, infection assays using the Galleria mellonella model confirmed its low virulenceFil: Repizo, Guillermo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Espariz, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Blancato, Victor Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Suárez, Cristian Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Esteban, Luis. Universidad Nacional de Rosario. Facultad de Cs.médicas. Escuela de Cs.médicas. Cátedra de Fisiología; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Prevalence and antibiotic resistance of Enterococcus strains isolated from poultry

The aim of this study was to evaluate the frequency of occurrence of bacteria of the genus Enterococcus in poultry, to identify them by means of matrixassisted laser desorption/ionisation time-of-flight mass spectrometry (MALDITOF MS), and to analyse the antimicrobial susceptibility of the isolated strains to the drugs most frequently used in poultry. The material for the bacteriological tests was obtained mainly from the heart (97%) of the birds investigated. Of a total of 2,970 samples tested, 911 (30.7%) tested positive for Enterococcus spp. Enterococci were detected in broilers (88.1%), laying hens (5.3%), turkeys (3.9%), breeding hens (2.2%), and geese (0.4%). The most commonly identified species were Enterococcus (E.) faecalis (74.7%), E. faecium (10.1%), E. gallinarum (5.5%), E. hirae (4.6%), and E. cecorum (4.1%). The most frequent resistance properties were resistance to sulphamethoxazole/trimethoprim (88%), tylosin (71.4%), enrofloxacin (69.4%), doxycycline (67.3%), and lincomycin/spectinomycin (56.1%). Only one vancomycin-resistant Enterococcus, E. cecorum from a broiler, was found

La doble faceta del género enterococcus, y su importancia en alimentos

El género Enterococcus incluye a un conjunto de microorganismos extremadamente versátiles, capaces de provocar infecciones hospitalarias principalmente en individuos con enfermedades subyacentes o inmunodeprimidos. Determinados componentes celulares pueden actuar como factores de virulencia en las infecciones enterocócicas, lo que junto con la resistencia adquirida a diferentes antimicrobianos hacen más difícil su erradicación. Los enterococos forman parte de la microbiota intestinal normal de individuos sanos, y están presentes en muchos alimentos. Poseen propiedades tecnológicas de interés como sus actividades glicolítica, lipolítica y proteolítica, y la producción de bacteriocinas. Están presentes en numerosos quesos regionales, jugando un papel importante en su maduración. Esta doble faceta despierta una gran inquietud sobre la seguridad de las cepas presentes en alimentos, y aquellas sociadas a ambientes hospitalarios