查看更多>>摘要：? 2022 Elsevier GmbHStrains of the psychrotrophic bacterium Lactococcus piscium have gained increasing attention as potentially bioprotective cultures due to their assertiveness against fish and meat spoilage bacteria as well as pathogenic bacteria. Recently, we have described two novel species within the genus Lactococcus (Lc.) namely Lc. carnosus (TMW 2.1612T) and Lc. paracarnosus (TMW 2.1615T) isolated from modified atmosphere packaged meat. Within this study, we compared the genomes of two Lc. carnosus strains, two Lc. paracarnosus strains and 16 Lc. piscium strains from our laboratory and five publicly available genomes previously affiliated to the species Lc. piscium. Our phylogenetic analysis supports reclassification of 20 of the strains to either Lc. carnosus or Lc. paracarnosus, so far limiting the Lc. piscium type strain (DSM 6634T) as sole representative of this species. Comparative genomics approach was conducted to predict underlying mechanisms involved in interspecies competition strategies of Lc. carnosus and Lc. paracarnosus against meat spoilers and predict their lifestyle in meat environments. In general, strains of the three species were highly similar regarding metabolic pathways for most of the relevant meat-derived substrates. In silico analyses enabled prediction of homolactic hexose fermentation by Lc. carnosus, Lc. paracarnosus and Lc. piscium. Further, genes required for the heterofermentative metabolism of hexoses and pentoses were only found in the Lc. pisicum type strain (DSM 6634T). We predict a low spoilage potential for Lc. carnosus and Lc. paracarnosus strains. No genes for decarboxylation of amino acids yielding biogenic amines were found in the genomes. Regarding their antimicrobial mechanisms against spoilers, we found a strain-specific putative polymorphic toxin system predictively delivered by the type VIIb secretion system, enabling cell-to-cell contact-dependent growth inhibition. Furthermore, we found additional genes predictively involved to the suppression of spoilers within the food microbiome (prophages, lytic domains, bacteriocins, metabolites).
查看更多>>摘要：? 2022 Elsevier GmbHPathogenic properties of orthologues to S. aureus staphylococcal enterotoxin C (SEC) and staphylococcal enterotoxin L (SEL) produced by S. epidermidis are largely unexplored. We assessed the enteropathogenic effects of S. epidermidis SECepi and SELepi and S. aureus SEC3 and SEL after oral administration to Balb/c mice. Intestinal sections from SE-treated mice were analyzed histopathologically. The T cell lineage markers (αβ and γδ TCR CD3, CD4, CD8), T-cell activation marker CD69 and proliferation-related marker CD71 were assessed in intraepithelial lymphocytes (IEL), mesenteric lymph nodes (MLN) and spleens (SPL). Serum concentrations of SEC and SEL were determined. Ortologous S. epidermidis and S. aureus SEs exerted a number of common histopathological changes in the mouse gut. Atrophy, generation of villi gap and edema of the villi were the most prominent effects of SE treatment observed in mouse gut sections. The most marked effect of ortologous S. epidermidis and S. aureus SEs on the number of goblet cells, crypt depth and villi height was noted in the mice duodenum and jejunum. We indicate early changes of TCRαβ CD4-CD8a+ T and TCRαβ CD4+CD8a+ T cells in response to both S. aureus and S. epidermidis SEs. Upon the treatment with SEs, markers of T cell activation and proliferation were upregulated in both αβ and γδ T cell populations derived from IEL and MLN. We demonstrated that S. epidermidis-encoded SEs applied via oral route exert pathological changes in mice gut similarly to S. aureus-encoded SEs. For the first time we indicated that SEL co-produced together with SEC by both S. aureus and S. epidermidis induces some elements of mice gut immune response and contributes to gastrointestinal tract damage. Our results indicate the potential involvement of CoNS-encoded enterotoxins in the pathogenesis of SFP.
查看更多>>摘要：? 2022 Elsevier GmbHArsenic (As) contamination is a global problem, and seriously threatens the ecosystems and human health. Over decades, numerous efforts regarding the microorganism-mediated bioremediation have been attempted to control the As-contaminated environments. This review article introduces the distribution feature, health risk, and remediation methods of As contamination, and systematically elaborates the characteristics and classification of As-remediating microorganism, including bacteria (e.g., Stenotrophomonas spp.), archaea (e.g., Halorubrum spp.), and fungi (e.g., Aspergillus spp.). Furthermore, functional microorganism can interact with As in various forms including redox, biomethylation, biosorption, and bioaccumulation, thereby playing an important role in As bioremediation and ecological balance. Studies on molecular mechanisms of microorganism-mediated As-bioremediation enhance the understanding of interaction between microorganism and As, and further guide the alleviation and removal of As contamination. Although bioremediation is recognized as a promising novel way in the prevention and control of As-contaminated environments, further studies are encouraged to provide more valuable data for its practical application.
查看更多>>摘要：? 2022 Elsevier GmbHCandida albicans is a commensal microorganism of the human microbiota that can be associated with superficial to disseminated infections. This species possesses several attributes that contribute to pathogenesis and virulence, such as the ability to transition from yeast to hyphae forms. During this transition, several changes occur in the fungal cell wall, which is the first point of contact between the pathogen and the host. The cell wall is a bi-layered structure, containing chitin, glucan, and proteins, the latter of which play important roles in pathogenesis. Given the importance of this structure, particularly in filamentation, this review focuses on the studies of C. albicans mutants for genes that encode cell wall-associated proteins that have an important role in the virulence, and also have a role in hyphal morphogenesis. Thus, we highlight some proteins whose mutation is associated with attenuated virulence in vivo and have defective filamentation. We also provide examples of proteins whose inactivation does not impair the filamentation yet are still important for C. albicans virulence.
NSTL
Elsevier