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At least 109 records · Page 6Linked to original sources
PubMed2024

Effects of initial corncob particle size on the short-term composting for preparation of cultivation substrates for Pleurotus ostreatus.

The short-term composting based on corncob for preparing Pleurotus ostreatus cultivation medium originated from agricultural production practices and so lacked systematic investigation. In this study, the influences of a Dafen (15 mm, DFT) and Xiaofen (5 mm, XFT) initial particle size (IPS) of corncob on the microbial succession and compost quality were examined. Results demonstrated that XFT compost was better suited for mushroom cultivation due to its high biological efficiency of 70 % and the absence of contamination. The composting microbes differed significantly between the DFT and XFT composts. During composting, the genera of Bacillus, Acinetobacter, Lactobacillus, Streptomyces, and Paenibacillus were majorly found in the DFT compost, while Acinetobacter, Lactobacillus, Puccinia, Bacteroides, and Bacillus genera dominated the XFT compost. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that throughout the thermophilic phase, XFT compost had much greater relative abundances of sequences relevant to energy, carbohydrate, and amino acid metabolism than DFT compost. Analysis of network correlations and Mantel tests indicated that IPS reduction could increase microbial interactions. Overall, adjusting the IPS of corncob to 5 mm increased microbial interactions, improved compost quality, and thereby boosted the P. ostreatus yield. These findings will be pertinent in optimizing the composting process of cultivation medium for P. ostreatus.

Composting↗
PubMed2024

Metagenome reveals the possible mechanism that microbial strains promote methanogenesis during anaerobic digestion of food waste.

For better understanding the mechanism of microbial strains promoting methane production, four strains Hungatella xylanolytica A5, Bacillus licheniformis B1, Paraclostridium benzoelyticum C2 and Advenella faeciporci E1 were inoculated into anaerobic digestion systems. After bioaugmentation, the cumulative methane production of A5, B1, C2 and E1 groups elevated by 11.68%, 8.20%, 18.21% and 15.67% compared to CK group, respectively. The metagenomic analysis revealed that the species diversity and uniformity of the experimental groups was improved, and hydrolytic acidifying bacteria, represented by Clostridiaceae, Anaerolineaceae and Oscillospiraceae, and methanogens, such as Methanotrichaceae and Methanobacteriaceae, were enriched. Meanwhile, the abundance of key genes in carbohydrate, pyruvate and methane metabolism was increased in the inoculated groups, providing reasonable reasons for more methane production. The strengthening mechanism of microbial strains in this study offered a theoretical foundation for selecting a suitable bioaugmentation strategy to solve the problems of slow start-up and low methane production in anaerobic digestion.

Methane↗
PubMedDate not supplied

Secretory immunity and the bacterial IgA proteases.

The characteristics and functions of microbial IgA proteases are reviewed. These enzymes represent a structurally heterogeneous group of proteins that are secreted into the extracellular environment by bacteria capable of causing human disease. The IgA proteases, which vary in their requirements for metal ions, are neutral endopeptidases whose role in the infectious process is not known but whose pronounced substrate specificity for human proteins of the IgA1 subclass has repeatedly been demonstrated. As reagents, the IgA proteases are useful in cleaving IgA molecules to yield intact Fc alpha and Fab alpha fragments that will allow the study of the structure and function of the two large regions of IgA immunoglobulin proteins. The role, if any, of these enzymes in promoting infection by pathogenic members of the genera Neisseria, Hemophilus, and Streptococcus is not known, although the secretory immune system is primarily mediated by antibodies of the IgA isotype, among which are IgA1 subclass proteins, and these proteins are susceptible to cleavage by IgA protease. The determination of the role of these enzymes in the pathogenesis of human infection must await clearer understanding of antigenicity and antibody function at secretory sites and of the relative roles of the two subclasses of human IgA in immune defense.

Bacteria↗
PubMed1990

Perfluorochemicals for gas transport and improvement of cell cultures.

This paper has considered the effects and potential application of PFCs, their emulsions and emulsion components for regulating growth and metabolic functions of microbial, animal and plant cells in culture. PFCs will help to overcome problems encountered in conventional culture systems (e.g. limited gas supply, mechanical damage), especially where cells are grown to high density. While the commercial potential of PFCs for in vitro systems has not yet been fully exploited, the most exciting areas for future developments are in the culture of animal and plant cell lines of importance in biotechnology and medicine.

Animals↗
PubMed1992

Heat shock proteins in health and disease.

Heat shock proteins are among the most abundant proteins of the biosphere. They not only play a major role under stress conditions but also perform important physiological functions. The present review summarizes the potential contribution of heat shock proteins to health and disease related to immunity: their contribution to antibody assembly and antigen presentation; their role in host cell protection against "immune stress"; their participation in tumor surveillance; their relation to gamma/delta T-cell recognition; their function as microbial virulence factors; their dominant antigenicity for the immune response against microbial pathogens; and their possible role as autoantigens. The findings summarized here illustrate the marked liaison between heat shock proteins and the immune response, which may be both beneficial and detrimental to the host.

Animals↗
PubMed2025

CoverM: read alignment statistics for metagenomics.

SUMMARY: Genome-centric analysis of metagenomic samples is a powerful method for understanding the function of microbial communities. Calculating read coverage is a central part of analysis, enabling differential coverage binning for recovery of genomes and estimation of microbial community composition. Coverage is determined by processing read alignments to reference sequences of either contigs or genomes. Per-reference coverage is typically calculated in an ad-hoc manner, with each software package providing its own implementation and specific definition of coverage. Here we present a unified software package CoverM which calculates several coverage statistics for contigs and genomes in an ergonomic and flexible manner. It uses "Mosdepth arrays" for computational efficiency and avoids unnecessary I/O overhead by calculating coverage statistics from streamed read alignment results. AVAILABILITY AND IMPLEMENTATION: CoverM is free software available at https://github.com/wwood/coverm. CoverM is implemented in Rust, with Python (https://github.com/apcamargo/pycoverm) and Julia (https://github.com/JuliaBinaryWrappers/CoverM_jll.jl) interfaces.

Metabolomics↗
PubMed1990

Gamma delta T cell receptor-bearing lymphocytes during Epstein-Barr virus infection.

Lymphocytes bearing gamma delta T cell receptors (TCR) constitute a minor subpopulation of human peripheral blood lymphocytes. Their role and function during microbial infections are largely unknown. In 10 patients with Epstein-Barr virus-induced infectious mononucleosis, the gamma delta TCR-expressing T cell population expanded during the acute phase. These cells were largely delta TCS1-, CD4-, and CD8- but expressed activation antigens such as human leukocyte antigen-DR and CD38. The convalescent phase of infectious mononucleosis was characterized by a relative persistence of gamma delta T cells. Together these data suggest a possible role of gamma delta T cells in the control of primary Epstein-Barr virus infection in humans.

Acute Disease↗
PubMed1995

M proteins of group G streptococci: mechanisms of resistance to phagocytosis.

Group G streptococci that express M protein and resist phagocytosis in human blood (virulent strains) were compared with strains of groups G and A that are readily phagocytosed (avirulent). Virulent group G streptococci were less effective (P < .05) as activators of the alternative complement pathway (ACP) than were avirulent streptococci. In immunofluorescence studies, C3 bound more avidly to avirulent than to virulent group G streptococci. Resistance of virulent group G strains to ACP opsonization and to phagocytosis was markedly diminished by removal with pepsin of the type-specific portion of the M molecule. Preincubation with fibrinogen did not diminish ACP activation or C3 binding by virulent group G and A streptococci but did exert an antiphagocytic effect. Given the similarity of M proteins of groups G and A in structure and function, other microbial constituents are likely responsible for differences in the spectra of illnesses attributable to the two serogroups.

Antigens, Bacterial↗
PubMed1986

Enhancement of Streptococcus faecalis infection and complement depletion in yeast-treated mice.

Enhancement of Streptococcus faecalis infection and lowering of the complement level have been demonstrated in mice injected with a heat-treated suspension of baker's yeast (Saccharomyces cerevisiae). The leucocyte response to the infection was not affected. The yeast preparation showed, in vitro, an intense anti-complementary activity on mouse serum and interfered with the microbial killing function of the mouse peritoneal macrophages. No significant stimulation of the growth of S. faecalis in vitro in the presence of the yeast was observed. The enhancement of the infection in mice treated with the yeast seems to be mediated, mainly, by complement depletion.

Animals↗
PubMed2025

Cobamide-based interactions between soil bacteria can be predicted based on monoculture growth.

Interactions between microbes shape the structure and function of microbial communities. While studying interactions is key to understanding microbial communities as a whole, gaining a detailed mechanistic view is challenging due to the scale of co-occurring interactions. The model nutrient approach enables the study of a subset of interactions involving a single nutrient class and can shed light on broader interaction mechanisms involving other nutrients. Here, we focus on cobamides, the cobalamin (vitamin B12) family of enzyme cofactors, to study nutrient competition and nutrient-sharing interactions in co-cultures and tri-cultures. We examined bacteria that were previously isolated from a grassland soil and were characterized as "dependents" (require cobamides but cannot synthesize them) or "producers" (synthesize cobamides). The outcome of competition between a pair of dependents was predictable based on monoculture growth characteristics, with the dominant microbe determined by its adaptation to a specific cobamide concentration range. Moreover, cobamide producers could support the cobamide-dependent growth of dependents in co-culture and influenced the outcome of competition between dependents in tri-culture. We analyzed the metabolic capacity encoded in the genomes of producers and dependents and found that cobamides are likely the main shared nutrient in our co- and tri-cultures. These results highlight the utility of the model nutrient approach to characterize and predict interactions in bacterial consortia of increasing complexity.

Journal Article↗
PubMed1993

Tetanus toxin selectively impairs anti-tumoral but not anti-microbial macrophage-mediated effector functions.

The present study was designed to establish the susceptibility of macrophage-mediated effector functions to tetanus toxin (TT). Using the murine macrophage cell line, GG2EE, generated in vitro by v-raf/v-myc oncogenes, we have previously provided evidence that TT selectively inhibits interferon gamma (IFN-gamma), but not basal, lysozyme activity. Here we show that while neither phagocytic nor candidacidal activities are affected by TT treatment, antitumoral activity is significantly impaired after exposure to TT. This phenomenon, which is dose-dependent, is fully ascribed to the holotoxin, as heat inactivated TT, C or A-B fragments result ineffective. Furthermore, C but not A-B fragment competes with TT in abrogating its inhibitory effects. Overall, these data indicate that TT is not a broad-spectrum, down-regulating signal on macrophage-mediated functions, thus implying that its toxic action is exerted on specific molecular targets.

Animals↗
PubMed1992

Consequences of microbial attachment: directing host cell functions with adhesins.

We take the view that adherence is not just a static process of holding hands but rather elicits a response in the targeted cell. From this point of view, adherence is an active process with an outcome. This outcome or fate is predictable only when several parameters of the host cell-adhesin interaction are known: is the adhesin acting alone or in series with other products, is the receptor up- or down-regulated at the time of ligation, which domain of the receptor is bound, and finally, which intracellular response circuits are connected to the receptor in the cell type targeted? Variations in these parameters are the basis for the ability of the adhesins of pathogens to orchestrate outcomes as disparate as simple address recognition versus actin nucleation, cytokine induction, activation of plasmin, derangement of leukocyte migration, or deposition of antibody on host cell membranes. The recognition of the relatedness of some eukaryotic and prokaryotic adhesive domains and the shared use of existing eukaryotic cell-cell interaction systems between host and pathogen suggest that the cellular interactions of interest in eukaryotic cell biology can be revealed by taking clues from the pathogens, which have studied and adapted to them the longest.

Animals↗
PubMedDate not supplied

Effect of different combinations of dietary additives on bacterial translocation and survival in gut-derived sepsis.

BACKGROUND: Dietary arginine, glutamine, and fish oil each have been shown to improve resistance to infection. The purpose of this study was to assess the potential benefit of different combinations and amounts of these components on bacterial translocation and related mortality during gut-derived sepsis. METHODS: Balb/c mice were fed for 10 days with an AIN-76A diet supplemented with different combinations and percentages of arginine, glutamine, glycine, fish oil, and medium-chain triglycerides. Controls were fed a complete AIN-76A diet or chow. After 10 days of feeding, all animals were transfused. On day 15, the animals were gavaged with 10(10) 111In-radiolabeled or unlabeled Escherichia coli and given a 30% burn injury. Animals gavaged with unlabeled bacteria were observed for survival (n = 317). Groups that showed the best survival as well as control groups were gavaged with labeled bacteria and killed 4 hours postburn (n = 60) for harvest of mesenteric lymph nodes, liver and spleen. RESULTS: Mice fed diets enriched with 5% fish oil + 2% arginine, 2% arginine + 2% glutamine, or 5% fish oil + 2% glutamine had higher survival than control groups. The animals fed fish oil+glutamine had significantly reduced translocation to the liver and spleen. Animals fed arginine+glutamine had an enhanced ability to kill translocated organisms in the liver compared with other groups. Fish oil+arginine improved both barrier function and microbial killing. CONCLUSIONS: Feeding with arginine+glutamine, fish oil+arginine, or fish oil+glutamine supplemented diets positively affects the outcome in a gut-derived sepsis model.

Animals↗
PubMed1994

The roles of magnesium in biotechnology.

This review highlights the important roles played by magnesium in the growth and metabolic functions of microbial and animal cells, and therefore assigns a key role for magnesium ions in biotechnology. The fundamental biochemical and physiological actions of magnesium as a regulatory cation are outlined. Such actions are deemed to be relevant in an applied sense, because Mg2+ availability in cell culture and fermentation media can dramatically influence growth and metabolism of cells. Manipulation of extracellular and intracellular magnesium ions can thus be envisaged as a relatively simplistic, but nevertheless versatile, means of physiological cell engineering. In addition, biological antagonism between calcium and magnesium at the molecular level may have profound consequences for the optimization of biotechnological processes that exploit cells. In fermentation, for example, it is argued that the efficiency of microbial conversion of substrate to product may be improved by altering Mg:Ca concentration ratios in industrial feedstocks in a way that makes more magnesium available to the cells. With particular respect to yeast-based biotechnologies, magnesium availability is seen as being crucially important in governing central pathways of carbohydrate catabolism, especially ethanolic fermentation. It is proposed that such influences of magnesium ions are expressed at the combined levels of key enzyme activation and cell membrane stabilization. The former ensures optimum flow of substrate to ethanol and the latter acts to protect yeasts from physical and chemical stress.

Animals↗
PubMed1992

[The mechanisms of the manifestation of the genotoxic effects of binase].

The high concentrations of commercial sample of Bacillus intermedius 7P ribonuclease (binase) showed a weak mutagenic effect in Ames test and Ara-test. It has been established that binase induces the SOS-functions of microbial cell and prophage induction. The way of exogenic enzyme action through activation of RecA protein is proposed.

Bacillus↗
PubMed1983

[Lipopolysaccharide-protein complexes of the outer membrane of gram-negative bacteria].

The evidence for occurring lipopolysaccharide-protein complexes in the outer membrane of gram-negative bacteria has been summarized. The composition and supramolecular structure of these complexes as well as their functions in microbial envelope and substantial role in membrane organization have been discussed. The biological properties of the complexes as endotoxins and O-specific antigens have been considered.

Antigens, Bacterial↗