Search

Introduction: We sought to evaluate secondary infections (SIs) in patients admitted to the intensive care unit (ICU) for COVID-19 with respect to incidence, causative pathogens, and clinical outcomes. Methodology: In this two-centre retrospective study, we analysed 146 patients (96 males, 50 females; median age, 64 years) admitted to the ICU with COVID-19 between March 26 and December 31, 2020. Inclusion criteria were an ICU admission for at least 48 hours and age beyond 18 years. Patients with and without SIs were compared and the impacts of SIs and carbapenem resistance on mortality were analysed. Results: During ICU admission, 84 episodes of SIs developed in 58 patients (39.7%). A total of 104 isolates were recovered, with Gram-negative bacteria most frequent accounting for 74%. At least one carbapenem-resistant pathogen (n = 61) was recovered in 41 patients (70.1%). In multivariate analysis, the use of ECMO and an elevated procalcitonin level were significantly associated with the development of SIs. The mortality rate and the incidence of carbapenem resistance did not differ significantly in COVID-19 patients with and without SIs (p = 0.059 and p = 0.083, respectively). Conclusions: The incidences of SIs and carbapenem resistance among COVID-19 patients were alarming, emphasizing stricter infection control measures in the ICU setting. © 2022 Journal of Infection in Developing Countries. All rights reserved.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.Routine microscopic examination of biomass samples from many activated sludge plants around the world reveals the presence of large numbers of both Gram positive and Gram negative coccoid cells often arranged in distinctive tetrads or sheets of tetrads. Three Gram negative tetrad cocci were successfully isolated into pure culture using micromanipulation from samples of biomass from plants in Tamworth, N.S.W., Australia, Verona, Italy and Macau. After extensive phenotypic characterisation and 16S rDNA sequence analysis, all isolates showed high overall similarity to each other, but were phylogenetically quite different to any previously sequenced bacterium. They have therefore been classified as three species of a new genus, the genus Amaricoccus in the a Proteobacteria in the domain Bacteria. None could accumulate polyphosphate granules, and production of intracellular poly-beta-hydroxybutyrate (PHB) granules depended on the carbon source used in the medium. A similar characterisation of the original isolate of the G-bacteria described by Cech and Hartman showed this organism also belonged to the same genus as the other three isolates, but as a distinct species. The practical implications of these observations are discussed.

Pseudomonas species are prominent producers of lipopeptides that support proliferation in a multitude of environments and foster varied lifestyles. By genome mining of biosynthetic gene clusters (BGCs) with lipopeptide-specific organization, we mapped the global Pseudomonas lipopeptidome and linked its staggering diversity to taxonomy of the producers, belonging to different groups within the major Pseudomonas fluorescens lineage.

Synthetic communities grown in well-controlled conditions are an important tool to decipher the mechanisms driving community dynamics. However, replicate time series of synthetic human gut communities in chemostats are rare, and it is thus still an open question to what extent stochasticity impacts gut community dynamics. Here, we address this question with a synthetic human gut bacterial community using an automated fermentation system that allows for a larger number of biological replicates. We collected six biological replicates for a community initially consisting of five common gut bacterial species that fill different metabolic niches. After an initial 12 hours in batch mode, we switched to chemostat mode and observed the community to stabilize after 2-3 days. Community profiling with 16S rRNA resulted in high variability across replicate vessels and high technical variability, while the variability across replicates was significantly lower for flow cytometric data. Both techniques agree on the decrease in the abundance of Bacteroides thetaiotaomicron, accompanied by an initial increase in Blautia hydrogenotrophica. These changes occurred together with reproducible metabolic shifts, namely a fast depletion of glucose and trehalose concentration in batch followed by a decrease in formic acid and pyruvic acid concentrations within the first 12 hours after the switch to chemostat mode. In conclusion, the observed variability in the synthetic bacterial human gut community, as assessed with 16S rRNA gene sequencing, is largely due to technical variability. The low variability seen in HPLC and flow cytometry data suggests a highly deterministic system. ispartof: Gut Microbes vol:15 issue:1 ispartof: location:United States status: Published online

Bacteria can be harmless commensals, beneficial probiotics, or harmful pathogens. Therefore, mankind is challenged to detect and identify bacteria in order to prevent or treat bacterial infections. Examples are identification of species for treatment of infection in clinics and E. coli cell counting for water quality monitoring. Finally, in some instances, the pathogenicity of a species is of interest. The main strategies to investigate pathogenicity are detection of target genes which encode virulence factors. Another strategy could be based on phenotypic identification. Raman spectroscopy is a promising phenotypic method, which offers high sensitivities and specificities for the identification of bacteria species. In this study, we evaluated whether Raman microspectroscopy could be used to determine the pathogenicity of E. coli strains. We used Raman spectra of seven non-pathogenic and seven pathogenic E. coli strains to train a PCA-SVM model. Then, the obtained model was tested by identifying the pathogenicity of three additional E. coli strains. The pathogenicity of these three strains could be correctly identified with a mean sensitivity of 77%, which is suitable for a fast screening of pathogenicity of single bacterial cells. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s00216-020-02957-2) contains supplementary material, which is available to authorized users.

Minutes of the closed meeting of the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Rhizobia and Agrobacteria held by videoconference, 5 July 2021, followed by online discussion until 31 December 2021, and list of recent species.

Cyclic lipopeptides (CLiPs) are secondary metabolites secreted by a range of bacterial phyla. CLiPs from Pseudomonas in particular, display diverse structural variations in terms of the number of amino acid residues, macrocycle size, amino acid identity, and stereochemistry (e.g., d- versus l-amino acids). Reports detailing the discovery of novel or already characterized CLiPs from new sources appear regularly in literature. Increasingly, however, the lack of detailed characterization threatens to cause considerable confusion, especially if configurational heterogeneity is present for one or more amino acids. Using Pseudomonas CLiPs from the Bananamide, Orfamide, and Xantholysin groups as test cases, we demonstrate and validate that the combined 1H and 13C Nuclear Magnetic Resonance (NMR) chemical shifts of CLiPs constitute a spectral fingerprint that is sufficiently sensitive to differentiate between possible diastereomers of a particular sequence even when they only differ in a single d/l configuration. Rapid screening, involving simple matching of the NMR fingerprint of a newly isolated CLiP with that of a reference CLiP of known stereochemistry, can then be applied to resolve dead-ends in configurational characterization and avoid the much more cumbersome chemical characterization protocols. Even when the stereochemistry of a particular reference CLiP remains to be established, its spectral fingerprint allows to quickly verify whether a newly isolated CLiP is novel or already present in the reference collection. We show NMR fingerprinting leads to a simple approach for early on dereplication which should become more effective as more fingerprints are collected. To benefit research involving CLiPs, we have made a publicly available data repository accompanied by a 'knowledge base' at https://www.rhizoclip.be, where we present an overview of published NMR fingerprint data of characterized CLiPs, together with literature data on the originally determined structures. IMPORTANCE Pseudomonas CLiPs are ubiquitous specialized metabolites, impacting the producer's lifestyle and interactions with the (a)biotic environment. Consequently, they generate interest for agricultural and clinical applications. Establishing structure-activity relationships as a premise to their development is hindered because full structural characterization including stereochemical information requires labor-intensive analyses, without guarantee for success. Moreover, increasing use of superficial comparison with previously characterized CLiPs introduces or propagates erroneous attributions, clouding further scientific progress. We provide a generally applicable characterization methodology based on matching NMR spectral fingerprints of newly isolated CLiPs to natural and synthetic reference compounds with (un)known stereochemistry. In addition, NMR fingerprinting is shown to provide a suitable basis for structural dereplication. A publicly available reference compound repository promises to facilitate participation of the lipopeptide research community in structural assessment and dereplication of newly isolated CLiPs, which should also support further developments in genome mining for novel CLiPs. ispartof: MICROBIOLOGY SPECTRUM vol:10 issue:4 ispartof: location:United States status: published

15 Pág. Departamento de ​Protección Vegetal (INIA), 'Candidatus Liberibacter solanacearum' (CaLsol) is an uncultured bacterium, transmitted by psyllids and associated with several diseases in Solanaceae and Apiaceae crops. CaLsol detection in psyllids often requires insect destruction, preventing a subsequent morphological identification. In this work, we have assessed the influence on the detection of CaLsol by PCR in Bactericera trigonica (Hemiptera: Psyllidae), of four specimen preparations (entire body, ground, cut-off head, and punctured abdomen) and seven DNA extraction methods (PBS suspension, squashing on membrane, CTAB, Chelex, TRIsureTM, HotSHOT, and DNeasy®). DNA yield and purity ratios, time consumption, cost, and residues generated were also evaluated. Optimum results were obtained through grinding, but it is suggested that destructive procedures are not essential in order to detect CaLsol. Although CaLsol was detected by qPCR with DNA obtained by the different procedures, HotSHOT was the most sensitive method. In terms of time consumption and cost, squashed on membrane, HotSHOT, and PBS were the fastest, while HotSHOT and PBS were the cheapest. In summary, HotSHOT was accurate, fast, simple, and sufficiently sensitive to detect this bacterium within the vector. Additionally, cross-contamination with CaLsol was assessed in the ethanol solutions where B. trigonica specimens were usually collected and preserved. CaLsol-free psyllids were CaLsol-positive after incubation with CaLsol-positive specimens. This work provides a valuable guide when choosing a method to detect CaLsol in vectors according to the purpose of the study., This work was supported by the Spanish Ministry of Economy, Industry, and Competitiveness (Spanish projects RTA2013-00091-C02-01 and RTA2013-00091-C02-02) and by the Community of Madrid project S2018/BAA-4330.

In the marine environment, most solid surfaces are covered by microbial biofilms, mainly composed of bacteria and diatoms. The negative effects of biofilms on materials and equipment are numerous and pose a major problem for industry and human activities. Since marine micro-organisms are an important source of bioactive metabolites, it is possible that they synthesize natural ecofriendly molecules that inhibit the adhesion of organisms. In this work, the antibiofilm potential of marine bacteria was investigated using Flavobacterium sp. II2003 as a target. This strain is potentially a pioneer strain of bacteria that was previously selected from marine biofilms for its strong biofilm-forming ability. The culture supernatants of 86 marine heterotrophic bacteria were tested for their ability to inhibit Flavobacterium sp. II2003 biofilm formation and the Pseudomonas sp. IV2006 strain was identified as producing a strong antibiofilm activity. The Pseudomonas sp. IV2006 culture supernatant (SNIV2006) inhibited Flavobacterium sp. II2003 adhesion without killing the bacteria or inhibiting its growth. Moreover, SNIV2006 had no effect on the Flavobacterium sp. II2003 cell surface hydrophilic/hydrophobic and general Lewis acid–base characteristics, but modified the surface properties of glass, making it on the whole more hydrophilic and more alkaline and significantly reducing bacterial cell adhesion. The glass-coating molecules produced by Pseudomonas sp. IV2006 were found to probably be polysaccharides, whereas the antibiofilm molecules contained in SNIV2006 and acting during the 2 h adhesion step on glass and polystyrene surfaces would be proteinaceous. Finally, SNIV2006 exhibited a broad spectrum of antibiofilm activity on other marine bacteria such as Flavobacterium species that are pathogenic for fish, and human pathogens in both the medical environment, such as Staphylococcus aureus and Pseudomonas aeruginosa , and in the food industry, such as Yersinia enterocolitica . Thus, a wide range of applications could be envisaged for the SNIV2006 compounds, both in aquaculture and human health.

By 2030, the global incidence of cancer is expected to increase by approximately 50%. However, most conventional therapies still lack cancer selectivity, which can have severe unintended side effects on healthy body tissue. Despite being an unconventional and contentious therapy, the last two decades have seen a significant renaissance of bacterium-mediated cancer therapy (BMCT). Although promising, most present-day therapeutic bacterial candidates have not shown satisfactory efficacy, effectiveness, or safety. Furthermore, therapeutic bacterial candidates are available to only a few of the approximately 200 existing cancer types. Excitingly, the recent surge in BMCT has piqued the interest of non-BMCT microbiologists. To help advance these interests, in this paper we reviewed important aspects of cancer, present-day cancer treatments, and historical aspects of BMCT. Here, we provided a four-step framework that can be used in screening and identifying bacteria with cancer therapeutic potential, including those that are uncultivable. Systematic methodologies such as the ones suggested here could prove valuable to new BMCT researchers, including experienced non-BMCT researchers in possession of extensive knowledge and resources of bacterial genomics. Lastly, our analyses highlight the need to establish and standardize quantitative methods that can be used to identify and compare bacteria with important cancer therapeutic traits.

As a frequent inhabitant of sites polluted with toxic chemicals, the soil bacterium and plant-root colonizer Pseudomonas putida can tolerate high levels of endogenous and exogenous oxidative stress. Yet, the ultimate reason of such phenotypic property remains largely unknown. To shed light on this question, metabolic network-wide routes for NADPH generation— the metabolic currency that fuels redox-stress quenching mechanisms—were inspected when P. putida KT2440 was challenged with a sub-lethal H2O2 dose as a proxy of oxidative conditions. 13C-tracer experiments, metabolomics, and flux analysis, together with the assessment of physiological parameters and measurement of enzymatic activities, revealed a substantial flux reconfiguration in oxidative environments. In particular, periplasmic glucose processing was rerouted to cytoplasmic oxidation, and the cyclic operation of the pentose phosphate pathway led to significant NADPH-forming fluxes, exceeding biosynthetic demands by ~50%. The resulting NADPH surplus, in turn, fueled the glutathione system for H2O2 reduction. These properties not only account for the tolerance of P. putida to environmental insults—some of which end up in the formation of reactive oxygen species—but they also highlight the value of this bacterial host as a platform for environmental bioremediation and metabolic engineering. The Novo Nordisk Foundation///Noruega European Union’s Horizon 2020 Research and Innovation Programme/[814418]//Unión Europea Danish Council for Independent Research///Dinamarca Madonna University/[H2020-FET-OPEN-RIA-2017-1-766975]/MADONNA/Estados Unidos BioRoboost/[H2020-NMBP-BIO-CSA-2018]//Unión Europea SynBio4Flav/[H2020-NMBP/0500]//Unión Europea Mix-Up: Contracts of European Union/[H2020-Grant 870294]/MIX-UP/Unión Europea Comunidad Autónoma de Madrid/[S2017/BMD-3691 InGEMICS-CM]//España UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones en Productos Naturales (CIPRONA)

In this article we have summarised our findings resulting from analysing the complete genome sequence of Pseudomonas umsongensis GO16 and we have determined experimentally its potential for the upcycling of monomers resulting from PET hydrolysis. Besides a general genomic characterisation, we have identified and validated the set of genes required for terephthalate and ethylene glycol degradation as well as the ability of the strain for producing short and medium‐chain length polyhydroxyalkanoates., Summary The throwaway culture related to the single‐use materials such as polyethylene terephthalate (PET) has created a major environmental concern. Recycling of PET waste into biodegradable plastic polyhydroxyalkanoate (PHA) creates an opportunity to improve resource efficiency and contribute to a circular economy. We sequenced the genome of Pseudomonas umsongensis GO16 previously shown to convert PET‐derived terephthalic acid (TA) into PHA and performed an in‐depth genome analysis. GO16 can degrade a range of aromatic substrates in addition to TA, due to the presence of a catabolic plasmid pENK22. The genetic complement required for the degradation of TA via protocatechuate was identified and its functionality was confirmed by transferring the tph operon into Pseudomonas putida KT2440, which is unable to utilize TA naturally. We also identified the genes involved in ethylene glycol (EG) metabolism, the second PET monomer, and validated the capacity of GO16 to use EG as a sole source of carbon and energy. Moreover, GO16 possesses genes for the synthesis of both medium and short chain length PHA and we have demonstrated the capacity of the strain to convert mixed TA and EG into PHA. The metabolic versatility of GO16 highlights the potential of this organism for biotransformations using PET waste as a feedstock.

Knowledge of the functional roles and inter-species interactions is crucial for modulation of the gut microbiome for health. However, understanding of functional roles and inter-species interactions remains a major challenge due to the complexity and technical limitation in investigating the gut microbiome. We rationally designed and assembled a Diet based Minimal Microbiome (Db-MM) consisting of ten core gut bacteria that convert dietary fiber to short-chain fatty acids. The composition was assessed using 16S rRNA gene amplicon sequencing and gene expression by metatranscriptomics.

In the past, the potato plant microbiota and rhizosphere have been studied in detail to improve plant growth and fitness. However, less is known about the postharvest potato tuber microbiome and its role in storage stability. The storage stability of potatoes depends on genotype and storage conditions, but the soil in which tubers were grown could also play a role. To understand the ecology and functional role of the postharvest potato microbiota, we planted four potato varieties in five soil types and monitored them until the tubers started sprouting. During storage, the bacterial community of tubers was analysed by next-generation sequencing of the 16S rRNA gene amplicons. The potato tubers exhibited soil-dependent differences in sprouting behaviour. The statistical analysis revealed a strong shift of the tuber-associated bacterial community from harvest to dormancy break. By combining indicator species analysis and a correlation matrix, we predicted associations between members of the bacterial community and tuber sprouting behaviour. Based on this, we identified Flavobacterium sp. isolates, which were able to influence sprouting behaviour by inhibiting potato bud outgrowth.

Background Akkermansia muciniphila is a human gut microbe with a key role in the physiology of the intestinal mucus layer and reported associations with decreased body mass and increased gut barrier function and health. Despite its biomedical relevance, the genomic diversity of A. muciniphila remains understudied and that of closely related species, except for A. glycaniphila, unexplored. Results We present a large-scale population genomics analysis of the Akkermansia genus using 188 isolate genomes and 2226 genomes assembled from 18,600 metagenomes from humans and other animals. While we do not detect A. glycaniphila, the Akkermansia strains in the human gut can be grouped into five distinct candidate species, including A. muciniphila, that show remarkable whole-genome divergence despite surprisingly similar 16S rRNA gene sequences. These candidate species are likely human-specific, as they are detected in mice and non-human primates almost exclusively when kept in captivity. In humans, Akkermansia candidate species display ecological co-exclusion, diversified functional capabilities, and distinct patterns of associations with host body mass. Analysis of CRISPR-Cas loci reveals new variants and spacers targeting newly discovered putative bacteriophages. Remarkably, we observe an increased relative abundance of Akkermansia when cognate predicted bacteriophages are present, suggesting ecological interactions. A. muciniphila further exhibits subspecies-level genetic stratification with associated functional differences such as a putative exo/lipopolysaccharide operon. Conclusions We uncover a large phylogenetic and functional diversity of the Akkermansia genus in humans. This variability should be considered in the ongoing experimental and metagenomic efforts to characterize the health-associated properties of A. muciniphila and related bacteria.

Plasmid-mediated polymyxin resistance was first described in 2015, in China, in Escherichia coli carrying the mcr-1 (Mobile Colistin Resistance-1) gene. Since then, it has become a major public health challenge worldwide, representing a major threat to human and animal health. In addition, there are still few reports on the prevalence of mcr-1 in Enterobacteriaceae isolated from humans, animals and food. Therefore, the purpose of the study was to investigate the occurrence of the mcr-1 gene in bacterial isolates with phenotypic resistance to polymyxin B obtained from clinical specimens of companion animals. Phenotypic resistance to polymyxin B were determined by broth microdilution and the susceptibility profile to other antimicrobials (amikacin, amoxicillin/clavulanate, ampicillin, ampicillin/sulbactam, aztreonam, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, doxycycline, ertapenem, gentamicin, imipenem, marbofloxacin, meropenem, phosphomycin, piperacillin/tazobactam, tetracycline, ticarcillin/clavulanate, tobramycin and trimethoprim/sulfamethoxazole) by disc-diffusion agar method. The extraction of bacterial DNA was performed via heat shock followed by spectrophotometric evaluation. To verify the presence of mcr-1, the Polymerase Chain Reaction was employed using specific primers, followed by agarose gel electrophoresis. The positive isolates had the corresponding amplicons sequenced. In this study, there were identified the first isolates of Escherichia coli, Klebsiella spp. and Enterobacter spp. carrying the mcr-1 gene derived from specimens of companion animals in Brazil. Our results suggest the dissemination of resistance to polymyxins in the community and the environment, highlighting the need for surveillance and optimized treatment guidelines. RESUMO: A resistência à polimixina mediada por plasmídeo teve sua primeira descrição em 2015, na China, em Escherichia coli portadora do gene mcr-1 (Mobile Colistin Resistance-1) e a partir de então tornou-se um grande desafio para a saúde pública em todo o mundo, constituindo uma grande ameaça à saúde humana e animal. Além disso, ainda existem poucos relatos sobre a prevalência de mcr-1 em Enterobacteriaceae isoladas de humanos, animais e alimentos. Sendo assim, o objetivo do estudo foi investigar a ocorrência do gene mcr-1 em isolados bacterianos com resistência fenotípica à polimixina B, oriundos de materiais clínicos de animais de companhia. A resistência fenotípica à polimixina B foi determinada por microdiluição em caldo e o perfil de sensibilidade aos demais antimicrobianos (amicacina, amoxicilina/clavulanato, ampicilina, ampicilina/sulbactam, aztreonam, cefazolina, cefepime, cefotaxima, cefoxitina, ceftazidima, ceftriaxona, cloranfenicol, ciprofloxacina, doxiciclina, ertapenem, gentamicina, imipinem, marbofloxacino, meropenem, fosfomicina, piperacilina/tazobactam, tetraciclina, ticarcilina/clavulanato, tobramicina sulfametoxazol/trimetoprim) foram determinados pelo método disco difusão. A extração do DNA bacteriano foi realizada via choque térmico, seguido de avaliação espectrofotométrica. Para a verificação da presença do mcr-1 foi utilizada a Reação em Cadeia da Polimerase com emprego de iniciadores específicos, seguida de eletroforese em gel de agarose. Os isolados positivos tiveram os correspondentes amplicons sequenciados. Nesse estudo foram identificados os primeiros isolados de Escherichia coli, Klebsiella spp. e Enterobacter spp. portadores do gene mcr-1 derivados de espécimes de animais de companhia no Brasil. Este estudo sugere a disseminação da resistência às polimixinas na comunidade e no meio ambiente, destacando a necessidade de vigilância e diretrizes otimizadas de tratamento.

Xylella fastidiosa is a vector-borne bacterium that causes diseases in many plants of economic interest. The bacterium&ndash, vector initial interactions involve bacterial membrane-bound adhesins that mediate cell attachment to the foregut of insect vectors. We investigated the role of the afimbrial adhesin XadA2 in the binding and biofilm formation of X. fastidiosa subsp. pauca to vector surfaces in vitro, as well as its potential to disrupt pathogen transmission. We showed that XadA2 has binding affinity for polysaccharides on sharpshooter hindwings, used as a proxy for the interactions between X. fastidiosa and vectors. When in a medium without carbon sources, the bacterium used wing components, likely chitin, as a source of nutrients and formed a biofilm on the wing surface. There was a significant reduction in X. fastidiosa biofilm formation and cell aggregation on vector wings in competition assays with XadA2 or its specific antibody (anti-XadA2). Finally, pathogen acquisition and transmission to plant were significantly reduced when the vectors acquired X. fastidiosa from an artificial diet supplemented with anti-XadA2. These results show that XadA2 is important in mediating bacterial colonization in the insect and that it could be used as a target for blocking X. fastidiosa transmission.

The objective of the present study was to provide an updated classification for Burkholderia cepacia complex (Bcc) taxon K isolates. A representative set of 39 taxon K isolates were analyzed through multilocus sequence typing (MLST) and phylogenomic analyses. MLST analysis revealed the presence of at least six clusters of sequence types (STs) within taxon K, two of which contain the type strains of Burkholderia contaminans (ST-102) and Burkholderia lata (ST-101), and four corresponding to the previously defined taxa Other Bcc groups C, G, H and M. This clustering was largely supported by a phylogenomic tree which revealed three main clades. Isolates of B. contaminans and of Other Bcc groups C, G, and H represented a first clade which generally shared average nucleotide identity (ANI) and average digital DNA-DNA hybridization (dDDH) values at or above the 95–96% ANI and 70% dDDH thresholds for species delineation. A second clade consisted of Other Bcc group M bacteria and of four B. lata isolates and was supported by average ANI and dDDH values of 97.2 and 76.1% within this clade and average ANI and dDDH values of 94.5 and 57.2% toward the remaining B. lata isolates (including the type strain), which represented a third clade. We therefore concluded that isolates known as Other Bcc groups C, G, and H should be classified as B. contaminans, and propose a novel species, Burkholderia aenigmatica sp. nov., to accommodate Other Bcc M and B. lata ST-98, ST-103, and ST-119 isolates. Optimized MALDI-TOF MS databases for the identification of clinical Burkholderia isolates may provide correct species-level identification for some of these bacteria but would identify most of them as B. cepacia complex. MLST facilitates species-level identification of many taxon K strains but some may require comparative genomics for accurate species-level assignment. Finally, the inclusion of Other Bcc groups C, G, and H into B. contaminans affects the phenotype of this species minimally and the proposal to classify Other Bcc group M and B. lata ST-98, ST-103, and ST-119 strains as a novel Burkholderia species is supported by a distinctive phenotype, i.e., growth at 42°C and lysine decarboxylase activity.

Summary The d‐ and l‐forms of lactate are important fermentation metabolites produced by intestinal bacteria but are found to negatively affect mucosal barrier function and human health. Both enantiomers of lactate can be converted with acetate into the presumed beneficial butyrate by a phylogenetically related group of anaerobes, including Anaerobutyricum and Anaerostipes spp. This is a low energy yielding process with a partially unknown pathway in Anaerobutyricum and Anaerostipes spp. and hence, we sought to address this via a comparative genomics, proteomics and physiology approach. We compared growth of Anaerobutyricum soehngenii on lactate with that on sucrose and sorbitol. Comparative proteomics revealed complete pathway of butyrate formation from sucrose, sorbitol and lactate. Notably, a gene cluster, lctABCDEF was abundantly expressed when grown on lactate. This gene cluster encodes a lactate dehydrogenase (lctD), electron transport proteins A and B (lctCB), nickel‐dependent racemase (lctE), lactate permease (lctF) and short‐chain acyl‐CoA dehydrogenase (lctG). Investigation of available genomes of intestinal bacteria revealed this new gene cluster to be highly conserved in only Anaerobutyricum and Anaerostipes spp. Present study demonstrates that A. soehngenii and several related Anaerobutyricum and Anaerostipes spp. are highly adapted for a lifestyle involving lactate plus acetate utilization in the human intestinal tract.

A characteristic of bacterial zoonoses, diseases caused by bacteria that can be transmitted to humans from animals, is a propensity to re-emerge. Several studies demonstrate their ongoing transmission in Nigeria, the most populous country in Africa. However, as local epidemiological data on bacterial zoonoses are inadequate the extent and impact of these infectious diseases is under-reported. Consequently, they are not a targeted priority of national public health policies. This limited recognition is despite indications of their possible roles in the widespread prevalence of non-malarial undifferentiated fever in Nigeria. While a number of animal reservoirs and arthropod vectors have been identified in the transmission routes of these diseases, an escalation of cases of undiagnosed febrile illness highlights the urgent need for a comprehensive assessment of other potential reservoirs, vectors and transmission cycles that may increase the local risk of infection with bacterial zoonoses. Animal health interventions have been proposed as a cost-effective strategy. Here, we present a broad overview of bacterial zoonotic infections of humans in Nigeria in the context of evolving epidemiological patterns. Further, we propose that facilitating the operation of a community-based One Health program is essential to providing the comprehensive epidemiological information that is required to improve prioritization of bacterial zoonoses. This would provide a driver for much needed investment in relevant public health interventions in Africa's most populous country., Public Health; Infectious Disease; Medical Microbiology; Microbiology; Epidemiology; Bacteriology; Diagnostics; Bacterium; Zoonosis; Vector; Reservoir; transmission; fever; Nigeria; One Health

Summary The importance of Th1/interferon (IFN)-γ-mediated responses in mycobacterial infection has been well established. However, little is known about B cell-mediated immunity during Mycobacterium tuberculosis (Mtb) infection. Interleukin (IL)-10-producing B cells (B10 cells), a subset of B regulatory cells (Bregs), are implicated in modulating the immune response. Herein, we found that B10 cells were significantly increased in patients with tuberculosis. Furthermore, mannose-capped lipoarabinomannan (ManLAM), a major surface lipoglycan component from Mtb, induced a significant increase in B10 cells, which enriched in CD5+ B1a B cells. ManLAM induced IL-10 production mainly by activating MyD88/PI3K/AKT/Ap-1 and K63-linked ubiquitination of NF-κB essential modulator/nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathways in B cells via Toll-like receptor 2. IL-10 production by ManLAM-treated B cells further inhibited CD4+ Th1 polarization, leading to increased susceptibility to mycobacterial infection compared with ManLAM-treated IL-10−/− B group. Thus, we report a new immunoregulation mechanism in which Mtb ManLAM-induced B10 cells negatively regulate host anti-TB cellular immunity., Graphical Abstract, Highlights • Mtb mannose-capped lipoarabinomannan (ManLAM) induces IL-10 production in B cells • ManLAM-induced B10 cells enrich in CD5+ B1a B cells • ManLAM binding with TLR2 triggers MyD88 signaling pathways of B cells • ManLAM-induced B10 cells hinder CD4+Th1 immunity during Mtb infection in mice, Bacterium; Biological Sciences; Immune Response; Microbiology

This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW = 16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport. Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport. © 2018 The current study was partially supported by the project PROBIOSOLEA (reference 13551), co-funded by Programa Operacional Regional do Norte (ON.2—O Novo Norte), under the Quadro de Referência Estratégico Nacional (QREN) , through the European Regional Development Fund . The current study was also supported by the Research Line INSEAFOOD of the project INNOVMAR-Innovation and Sustainability in the Management and Exploitation of Marine Resources (reference NORTE-01-0145-FEDER-000035 ), funded by the Northern Regional Operational Programme (NORTE 2020) through the ERDF. B. Costas was supported by FCT, Portugal ( IF/00197/2015 ).

La presencia de bacterias patógenas, como Escherichia coli, afecta la calidad e inocuidad de las hortalizas que se consumen en fresco y se relaciona con graves problemas de salud. El objetivo de este trabajo fue determinar si 3 cepas diferentes de E. coli tienen la capacidad de penetrar y permanecer en plantas y frutos de tomate. Se siguió un diseño experimental completamente al azar, para lo cual se estableció un cultivo de tomate (variedad «Cid») en condiciones de invernadero y se evaluaron 3 tratamientos, T1 (E. coli O157: H7), T2 (E. coli de cultivo de tomate |#91;EcT|#93; O157: H16), T3 (E. coli de cultivo de espinaca |#91;EcH|#93; EcH O105ab) y un testigo T4, con 100 plantas cada uno y 4 formas de inoculación: en el sustrato, en el tallo, en el pecíolo y en el pedúnculo. Se realizaron muestreos en etapa vegetativa, floración, fructificación y madurez fisiológica para cuantificar en placa las UFC/g y saber si las bacterias lograban moverse y recuperarse en la raíz, el tallo, la flor y el fruto. Los grupos filogenéticos a los que correspondieron las bacterias recuperadas fueron confirmados mediante pruebas bioquímicas, serotipificación y PCR. A los 120 días la recuperación de bacterias en la planta fue del 23% (E. coli O157: H7), 28% (EcT O157: H16) y 55% (EcH O105ab) con la inoculación al sustrato, mientras que con la inoculación por punción la recuperación fue (en igual orden) del 5%, 3% y 4% a los 30 días; del 37%, 35% y 30% a los 90 días; y del 42%, 39% y 13% a los 65 días. Las cepas utilizadas mostraron la capacidad de entrar en la planta de tomate y de permanecer en ella y transportarse hasta llegar al fruto, sin producir síntomas que indiquen su presencia. The presence of pathogenic bacteria, such as Escherichia coli affects the quality and safety of vegetables that are consumed fresh and is associated with serious health problems. The objective of this study was to determine if three different strains of E. coli can penetrate and remain in plants and tomato fruits. A completely randomized experimental design was followed for which a tomato crop ("Cid" variety) was established under greenhouse conditions and three treatments were evaluated, T1 (E. coli O157: H7), T2 (E. coli from tomato cultivation |#91;EcT|#93; O157: H16), T3 (E. coli from spinach cultivation |#91;EcH|#93; O105ab) and a T4 control, with 100 plants each and four forms of inoculation: in the substrate, steam, petiole and the peduncle. Samples were carried out in vegetative stage, flowering, fruiting and physiological maturity to quantify in petri dish CFU/g and know if the bacteria managed to move around and recover in root, stem, flower and fruit. The phylogenetic groups that corresponded to the bacteria recovered were confirmed by biochemical tests, serotyping and PCR. At 120 days the recovery of bacteria in the plant was 23% (E. coli O157: H7), 28% (EcT O157: H16) and 55% (EcH O105ab) whit inoculation to the substrate while the inoculation by puncture the recovery was (in the same order) of 5%, 3%, and 4% at 30 days; 37%, 35% and 30% at 90 days; and 42%, 39% and 13% at 65 days. The strains submit the ability to enter the tomato plant and to stay in it and transported to the fruit, without producing that indicate their presence.

Extracellular vesicles are nanoscale particles which were identified about fifty years ago. The studies have shown that all of the gram-negative bacteria secrete extracellular vesicles during their normal growth. Today, the production of membrane vesicles has been reported by gram-positive bacteria, parasites, fungi, and mycobacteria. Since these nanoscale particles carry many of the bacterial components such as DNA, RNA, protein, endotoxin, and virulence molecules, they play a very important role in interacting with the environment and other bacteria. For this reason, many of these vesicles are considered as the transmission of pathogens, antigenic protein compounds, and the development of non-cellular vaccines, as well as drug delivery agents. The studies, have been carried in this field so far, have been focused on the pathogenic and physiological roles of these nanostructures in cross-species relationships. The focus of this article is on the role of extracellular bacterial vesicles and pathological and physiological functions which contribute to the interactions between bacteria and bacterium-host. Since these nanostructures play significant role in pathogenesis, gene transduction, regulation of gene expression, immune response regulation, and cellular signaling, further studies are needed on the medical application of these nanostructures as a new generation of vaccines, adjuvants, drug delivery agents.

The paper presents the results of studies on the testing of zeolite-hongurin for the preservation of cultures of the strain of bacteria Salmonella abortus equi "BN-12" in the conditions of the chamber (+4°C) and the freezer (-18°C) of the refrigerator. It was found that zeolite-hongurin can be used in the storage of microorganisms, since the bacteria Salmonella abortus equi "BN-12" adsorbed on the zeolite-hongurin during storage at temperature of 4° C to -18° C (respectively, in the freezing and refrigerating conditions chambers of the refrigerator), retain viability and pathogenicity for more than 12 months (observation period).

In this study, preparation and application of novel biocomposite materials for textile dye removal which are produced by immobilization of specific bacteria onto electrospun nanofibrous webs are presented. A textile dye remediating bacterial isolate, Clavibacter michiganensis, was selected for bacterial immobilization, a commercial reactive textile dye, Setazol Blue BRF-X, was selected as the target contaminant, and electrospun polycaprolactone (PCL) and polylactic acid (PIA) nanofibrous polymeric webs were selected for bacterial integration. Bacterial adhesion onto nanofibrous webs was monitored by scanning electron microscopy (SEM) imaging and optical density (OD) measurements were performed for the detached bacteria. After achieving sufficient amounts of immobilized bacteria on electrospun nanofibrous webs, equivalent web samples were utilized for testing the dye removal capabilities. Both bacteria/PCL and bacteria/PLA webs have shown efficient remediation of Setazol Blue BRF-X dye within 48 hat each tested concentration (50, 100 and 200 mg/L), and their removal performances were very similar to the free bacteria cells. The bacteria immobilized webs were then tested for five times of reuse at an initial dye concentration of 100 mg/L, and found as potentially reusable with higher bacterial immobilization and faster dye removal capacities at the end of the test. Overall, these findings suggest that electrospun nanofibrous webs are available platforms for bacterial integration and the bacteria immobilized webs can be used as starting inocula for use in remediation of textile dyes in wastewater systems. (C) 2017 Elsevier Ltd. All rights reserved.

Bu çalışma, 22-24 Kasım 2012 tarihleri arasında İstanbul[Türkiye]’da düzenlenen 16. Annual Meeting of the European-Society-of-Surgery (ESS)’da bildiri olarak sunulmuştur. Background: Laparoscopic cholecystectomy (LC) is the gold standard for the treatment of symptomatic gallbladder stones. As infections are rare in uncomplicated LC, it is widely accepted that prophylactic antibiotics need not be administered, and guidelines do not support routine antibiotic prophylaxis during elective LC. However, routine antibiotic prophylaxis for elective LC is still popular in many clinical settings. We investigated this situation in our department. Method: This randomized double-blind controlled study included 570 patients who underwent LC between March 2007 and February 2010. The exclusion criteria were antibiotic intake before surgery, steroid treatment, and the presence of pancreatitis, cholangitis, obstructive jaundice, cephalosporin allergy, or pregnancy. The patients were randomized into three groups. Group 1 (n = 193) received physiologic saline as placebo, Group 2 (n = 191) received a first-generation cephalosporin (cefazolin; 1 g), and Group 3 (n = 186) received a second-generation cephalosporin (cefuroksim aksetil; 750mg). Bile and epigastric and umbilical port tissue samples were harvested for culture. All patients were observed until the end of the fourth week after surgery. Patient age, sex, weight, American Society of Anesthesiologists (ASA) score, diabetes mellitus, smoking history, history of biliary colic in the past month, length of the hospital stay before the operation, operational findings (acute or chronic cholecystitis), operation duration, use of drainage, type of prophylaxis administered if any, culture results, surgical site infection (SSI) development, and time to SSI development along with associated treatments were evaluated. Results: There was no statistically significant difference between the groups with respect to any of the demographic and clinical features analyzed in this study. The SSI rate was 1.2% in total, and in Groups 1, 2, and 3, it was 1.5%, 1.04%, and 1.07%, respectively. There was no statistical difference regarding SSI among the groups (p = 1.00). Superficial SSI was observed in all groups, and in all patients, the site of infection was the entrance to the epigastric port through which the gallbladder had been removed. Conclusions: Surgical site infection is rare after LC, and antibiotic prophylaxis does not appear to affect the outcome significantly. Moreover, factors such as positive bile cultures, history of biliary attack, ASA score, diabetes, obesity, and smoking do not have any effect on SSI development. Thus, we conclude that antibiotic prophylaxis is not needed for elective LC. European Soc Surgery

Carbamazepine and diclofenac have been pointed out as important markers for environmental pollution by pharmaceuticals. This study reports on the isolation of bacterial strains capable to degrade these micropollutants from activated sludge of a municipal wastewater treatment plant (WWTP). After selective enrichments, one strain able to degrade diclofenac and two strains able to degrade carbamazepine were isolated. The strains were identified by 16S rRNA gene sequencing. Strain Brevibacterium sp. D4 was able to biodegrade 35% of 10 mg L−1 of diclofenac as a sole carbon source; periodic feeding with acetate as a supplementary carbon source resulted in enhancing biodegradation to levels up to 90%, with a concomitant increase of the biodegradation rate. Strains Starkeya sp. C11 and Rhizobium sp. C12 were able to biodegrade 30% of 10 mg L−1 of carbamazepine as a sole carbon source; supplementation with acetate did not improve the biodegradation of carbamazepine by these strains. The activated sludge harboured bacteria capable to degrade the two top priority environmental contaminants and may be potentially useful for biotechnological applications. © 2017 Elsevier V.S. Bessa and I.S. Moreira wish to acknowledge research grant from Funda??o para a Ci?ncia e a Tecnologia (FCT), Portugal (Ref. SFRH/BD/90146/2012 and SFRH/BPD/87251/2012, respectively) and Fundo Social Europeu (Programa Operacional Potencial Humano (POPH), Quadro de Refer?ncia Estrat?gico Nacional (QREN)). This work was supported by FCT through the projects PTDC/EBB-EBI/111699/2009, UID/Multi/04423/2013, PEst-OE/EQB/LA0016/2013 and PHARMADRUGS-CESPU-2014.

When it comes to the discovery and analysis of yet uncharted bacterial traits, pure cultures are essential as only these allow detailed morphological and physiological characterization as well as genetic manipulation. However, microbiologists are struggling to isolate and maintain the majority of bacterial strains, as mimicking their native environmental niches adequately can be a challenging task. Here, we report the diversity-driven cultivation, characterization and genome sequencing of 79 bacterial strains from all major taxonomic clades of the conspicuous bacterial phylum Planctomycetes. The samples were derived from different aquatic environments but close relatives could be isolated from geographically distinct regions and structurally diverse habitats, implying that ‘everything is everywhere’. With the discovery of lateral budding in ‘Kolteria novifilia’ and the capability of the members of the Saltatorellus clade to divide by binary fission as well as budding, we identified previously unknown modes of bacterial cell division. Alongside unobserved aspects of cell signalling and small-molecule production, our findings demonstrate that exploration beyond the well-established model organisms has the potential to increase our knowledge of bacterial diversity. We illustrate how ‘microbial dark matter’ can be accessed by cultivation techniques, expanding the organismic background for small-molecule research and drug-target detection., This work was funded by the Deutsche Forschungsgemeinschaft (grant no. JO 893/4-1) and the Volkswagen foundation (experiment no. 89256). M.Y.G. was funded by the NIH IRP at the US National Library of Medicine. Work in the Mascher lab was supported by the Deutsche Forschungsgemeinschaft (grant no. MA2837/2-2) and the Bundeministerium für Bildung und Forschung in the framework of the ERAnet Synthetic Biology (project: ERASynBio2-ECFexpress). R.A. and A.M. were funded by the Max Planck Society.

Staphylococcus aureus is a Gram-positive bacterium found frequently on a person’s skin and sometimes in their upper respiratory tract. Although regarded primarily as a commensal of the human microbiota S. aureus shows the ability to become an opportunistic pathogen. Hence, it is a common cause of skin and lung infections and of food poisoning. S. aureus forms biofilms, complex communities of bacteria inside an exopolysaccharide matrix, which adhere to different surfaces, including those associated with hospital-acquired infections such as catheters, shunts and other implanted medical devices. In this instance, the presence of proteins adsorbed to the surface of the biomaterial provides a nutrient source for bacterial growth. Due to antimicrobial resistance, use of longstanding antibiotics alone is increasingly an ineffective therapeutic intervention for biofilm-related infections. Therefore, a growing concern is the treatment of medical devices in order to prevent antibiotic resistance associated with routine handling of these items in a healthcare setting. Consequently, several different biotechnological approaches have targeted a practical solution to S. aureus biofilm formation. These include novel antibiotics administered alone or combined with other compounds, application of natural products like enzymes and antimicrobial peptides, and harnessing of nanoparticles and phage therapy. This brief article provides an overview of each of these cutting-edge methods aimed at inhibition of S. aureus biofilms. Development of an effective agent to prevent and treat biofilm formation would represent a significant step forward for infection control of methicillin-resistant S. aureus (MRSA) and other antibiotic-resistant strains that provides a major global public health challenge. J Microbiol Infect Dis 2019; 9(4):167-172.

Antibiotic resistance poses a tremendous threat to human health. To overcome this problem, it is essential to know the mechanism of antibiotic resistance in antibiotic-producing and pathogenic bacteria. This paper deals with this problem from four points of view. First, the antibiotic resistance genes in producers are discussed related to their biosynthesis. Most resistance genes are present within the biosynthetic gene clusters, but some genes such as paromomycin acetyltransferases are located far outside the gene cluster. Second, when the antibiotic resistance genes in pathogens are compared with those in the producers, resistance mechanisms have dependency on antibiotic classes, and, in addition, new types of resistance mechanisms such as Eis aminoglycoside acetyltransferase and self-sacrifice proteins in enediyne antibiotics emerge in pathogens. Third, the relationships of the resistance genes between producers and pathogens are reevaluated at their amino acid sequence as well as nucleotide sequence levels. Pathogenic bacteria possess other resistance mechanisms than those in antibiotic producers. In addition, resistance mechanisms are little different between early stage of antibiotic use and the present time, e.g., β-lactam resistance in Staphylococcus aureus. Lastly, guanine + cytosine (GC) barrier in gene transfer to pathogenic bacteria is considered. Now, the resistance genes constitute resistome composed of complicated mixture from divergent environments.

The metabolism of lactate is important for infant gut health and may lead to acute lactate and/or H2 accumulation, pain, and crying as observed in colicky infants. Functional human studies often faced ethical challenges due to invasive medical procedures; thus, in this study, we implemented PolyFermS fermentation models to mimic the infant proximal colon, which were inoculated with immobilized fecal microbiota of two 2-month-old infants. We investigated the impact of pH, retention time, and accumulation of dl-lactate on microbiota composition and metabolic activity. We found that a drop in pH from 6.0 to 5.0 led to increased LPB and decreased LUB concomitantly with lactate accumulation. Increasing the RT resulted in complete lactate consumption associated with increased LUB. Our data highlight for the first time the impact of key abiotic factors on the metabolism of lactate, which is an important intermediate product for ecology and infant health., The metabolism of lactate impacts infant gut health and may lead to acute accumulation of lactate and/or H2 associated with pain and crying of colicky infants. Because gut microbiota studies are limited due to ethical and safety concerns, in vitro fermentation models were developed as powerful tools to assess effects of environmental conditions on the gut microbiota. In this study, we established a continuous colonic fermentation model (PolyFermS), inoculated with immobilized fecal microbiota and mimicking the proximal colon of 2-month-old infants. We investigated the effects of pH and retention time (RT) on lactate metabolism and of lactate-utilizing bacteria (LUB) exhibiting little or no H2 production. We observed that a drop in pH from 6.0 to 5.0 increased the number of lactate-producing bacteria (LPB) and decreased LUB concomitantly with lactate accumulation. Increasing RT from 5 to 10 h at pH 5.0 resulted in complete lactate consumption associated with increased LUB. Supplementation with dl-lactate (60 mM) to mimic lactate accumulation promoted propionate and butyrate production with no effect on acetate production. We further demonstrated that lactate-utilizing Propionibacterium avidum was able to colonize the reactors 4 days after spiking, suggesting its ability to compete with other lactate-utilizing bacteria producing H2. In conclusion, we showed that PolyFermS is a suitable model for mimicking young infant colonic microbiota. We report for the first time pH and RT as strong drivers for composition and metabolic activity of infant gut microbiota, especially for the metabolism of lactate, which is a key intermediate product for ecology and infant health. IMPORTANCE The metabolism of lactate is important for infant gut health and may lead to acute lactate and/or H2 accumulation, pain, and crying as observed in colicky infants. Functional human studies often faced ethical challenges due to invasive medical procedures; thus, in this study, we implemented PolyFermS fermentation models to mimic the infant proximal colon, which were inoculated with immobilized fecal microbiota of two 2-month-old infants. We investigated the impact of pH, retention time, and accumulation of dl-lactate on microbiota composition and metabolic activity. We found that a drop in pH from 6.0 to 5.0 led to increased LPB and decreased LUB concomitantly with lactate accumulation. Increasing the RT resulted in complete lactate consumption associated with increased LUB. Our data highlight for the first time the impact of key abiotic factors on the metabolism of lactate, which is an important intermediate product for ecology and infant health.