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Microbiological Research
Urban & Fischer Verlag DmbH & Co.
Microbiological Research

Urban & Fischer Verlag DmbH & Co.

0944-5013

Microbiological Research/Journal Microbiological ResearchSCIEIAHCI
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    Host-specific signal perception by PsaR2 LuxR solo induces Pseudomonas syringae pv. actinidiae virulence traits

    Spinelli, FrancescoCellini, AntonioBuriani, GiampaoloCorreia, Cristiana...
    12页
    查看更多>>摘要：Plant-associated bacteria, including pathogens, recognise host-derived signals to activate specific responses. The genome of Pseudomonas syringae pv. actinidiae (Psa), the aetiological agent of bacterial canker of kiwifruit, encodes for three putative LuxR-like receptors. Proteins of this family are usually involved in the quorum sensing system, through the perception of autoinducers (AHLs) produced by a cognate LuxI. However, Psa does not produce AHLs according to the lack of LuxI-encoding gene. It has been proposed that the so-called LuxR solos may be involved in the perception of environmental stimuli. We thus hypothesised that Psa LuxR-like receptors could be involved in host-derived signal sensing.Psa virulence traits, i.e., biofilm formation, motility and endophytic colonisation, were stimulated by growing the pathogen in host plant extracts, but not in non-host plant extracts or rich medium. Moreover, the phenotypic analyses of Psa mutant strains lacking the LuxR solo-encoding genes, demonstrated that PsaR2 plays a major role in host recognition and induction of virulence responses. The heterologous expression of PsaR2, followed by affinity chromatography and fraction activity assessment, confirmed the specific recognition of plant-derived components by this sensor. Overall, these data provide a deeper understanding of the regulation of Psa virulence through interkingdom communication, which represents a interesting target for the development of tolerant/resistant genotypes or innovative control strategies.
      原文链接:
    • NSTL
    • Elsevier

    Psychrotrophic plant beneficial bacteria from the glacial ecosystem of Sikkim Himalaya: Genomic evidence for the cold adaptation and plant growth promotion

    Mukhia, SrijanaKumar, AnilKumari, PoonamKumar, Rakshak...
    13页
    查看更多>>摘要：Commercial biofertilizers tend to be ineffective in cold mountainous regions due to reduced metabolic activity of the microbial inoculants under low temperatures. Cold-adapted glacier bacteria with plant growth-promoting (PGP) properties may prove significant in developing cold-active biofertilizers for improving mountain agriculture. With this perspective, the cultivable bacterial diversity was documented from the East Rathong glacier ecosystem lying above 3900 masl of Sikkim Himalaya. A total of 120 bacterial isolates affiliated to Gammaproteobacteria (53.33%), Bacteroidetes (16.66%), Actinobacteria (15.83%), Betaproteobacteria (6.66%), Alphaproteobacteria (4.16%), and Firmicutes (3.33%) were recovered. Fifty-two isolates showed many in vitro PGP activities of phosphate solubilization (9-100 mu g/mL), siderophore production (0.3-100 psu) and phytohormone indole acetic acid production (0.3-139 mu g/mL) at 10 degrees C. Plant-based bioassays revealed an enhancement of shoot length by 21%, 22%, and 13% in ERGS5:01, ERMR1:04, and ERMR1:05, and root length by 14%, 17%, 11%, and 22% in ERGS4:06, ERGS5:01, ERMR1:04, and ERMR1:05 treated seeds respectively. An increased shoot dry weight of 4-29% in ERMR1:05 and ERMR1:04, and root dry weight of 42-98% was found in all the treatments. Genome analysis of four bacteria from diverse genera predicted many genes involved in the bacterial PGP activity. Comparative genome study highlighted the presence of PGP-associated unique genes for glucose dehydrogenase, siderophore receptor, tryptophan synthase, phosphate metabolism (phoH, P, Q, R, U), nitrate and nitrite reductase, TonB-dependent receptor, spermidine/putrescine ABC transporter etc. in the representative bacteria. The expression levels of seven cold stress-responsive genes in the cold-adapted bacterium ERGS4:06 using real-time quantitative PCR (RT-qPCR) showed an upregulation of all these genes by 6-17% at 10 degrees C, and by 3-33% during cold-shock, which indicates the cold adaptation strategy of the bacterium. Overall, this study signifies the psychrotrophic bacterial diversity from an extreme glacier environment as a potential tool for improving plant growth under cold environmental stress.
      原文链接:
    • NSTL
    • Elsevier

    Microbial community structure, physicochemical characteristics and predictive functionalities of the Mexican tepache fermented beverage

    Gutierrez-Sarmiento, WilbertPena-Ocana, Betsy AnaidLam-Gutierrez, AnayancyGuzman-Albores, Jorge Martin...
    12页
    查看更多>>摘要：Tepache is a native beverage from Mexico, which is usually elaborated with pineapple shells, brown cane sugar and is fermented naturally. Beneficial health effects have been attributed to its consumption; however, the total ecosystem of this beverage including chemicals (substrates for microbial growth, prebiotics, etc) and microbiota (probiotics), and potential functionality had not been studied. In this work, the analysis of the tepache beverage for its physicochemical characteristics, as well as its structure of microbial communities and the predictive metabolic functionalities was carried out. Chemical characterization was performed via enzymatic and GC-MS methods. The bacterial and fungal communities were identified by using 16S rRNA and ITS metabarcoding through Illumina MiSeq 2 x 300. The metabolic potential was predicted by in silico tools. This research showed that after 72 h of fermentation, the tepache physicochemical characteristics shifted to 9.5 Brix degrees and acidic pH. The content of ethanol, acetic and L-lactic acid increased significantly from 0.83 +/- 0.02 to 3.39 +/- 0.18 g/L, from 0.38 +/- 0.04 to 0.54 +/- 0.04 g/L and from 1.42 +/- 0.75 to 8.77 +/- 0.34 g/L, respectively. While, the total sugars was decreased from 123.43 +/- 2.01 to 84.70 +/- 2.34 g/L. The microbial diversity analysis showed a higher richness of bacterial communities and increased fungal evenness at the end of fermentation. At 72 h of fermentation the microbial community was dominated by Lactobacillus, Leuconostoc, Acetobacter and Lactococcus bacterial genera. As for the fungal community, Saccharomyces, Gibberella, Zygosaccharomyces, Candida, Meyerozyma, Talaromyces, Epicoccum and Kabatiella were found to be in most abundance. The predicted functionality profile evidenced a close-fitting relationship between fungal communities at 0 h with the bacterial communities at 72 h of fermentation. The metabolic potential showed that glycolysis and citrate cycle metabolism were predominant for fungal community, while glycolysis, fructose and tricarboxylic acid metabolism were more representative for the bacterial core. Tepache fermentation mainly occurred at two temporal successions. First, a lactic acid and ethanol fermentation dominated by lactic acid bacteria and yeast, and then an increase in acetogenic bacteria. This study revealed for the first time the physicochemical, microbiological changes and predictive functionality that are involved during tepache fermentation. These findings contributed to the knowledge of important microbial sources and could be essential to future efforts in manufacturing process. In addition, this work could help to analyze the health benefits that are empirically attributed to it by consumers.
      原文链接:
    • NSTL
    • Elsevier

    A tale of antiviral counterattacks in rotavirus infection

    Bhuinya, ArkadebDass, DebashreeBanerjee, AnweshaMukherjee, Anupam...
    8页
    查看更多>>摘要：Human rotaviruses are the utmost etiologic agents of infantile gastroenteritis in children under five years of age. To reduce childhood morbidity and mortality caused by this rotavirus infection, numerous efforts are being made worldwide in the form of better and universal immunisation programmes. Though few vaccines are in action, the lack of approved antiviral agents that have potential combative effects against the rotavirus infection in the host, remains a point of concern. This review focuses on recent insights into the development of naturally derived, RNA-silencing-based drug substances that show their anti-rotaviral activities by targeting and influencing different host and/or viral factors that contribute directly or indirectly to successful viral pathogenesis.
      原文链接:
    • NSTL
    • Elsevier

    Dysbiosis and intestinal inflammation caused by Salmonella Typhimurium in mice can be alleviated by preadministration of a lytic phage

    Bao, HongduoZhang, HuiZhou, YanZhu, Shujiao...
    9页
    查看更多>>摘要：Many studies have shown the efficacy of phage therapy in reducing intestinal pathogens. However, phage-based probiotic treatment is poorly studied in view of effects on the gut microbiota and intestinal inflammation. In this study, a lytic or a temperate phage (each at 4 x108 PFU per day) or a streptomycin solution (40 mg per day) were administered to mice via drinking water for 31 days. Subsequently, mice were challenged with Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium). S. Typhimurium does not serve as the host bacterium and is not lysed by both phages. For intestinal inflammation evaluation, mice were given one dose of streptomycin for 24 h before the S. Typhimurium challenge. High-throughput sequencing analysis revealed that the phylum Firmicutes became the most abundant in mice pretreated with phages. The alpha diversity of gut bacteria was higher in phage treated than in streptomycin treated mice. Moreover, pretreatment with the lytic and the temperate phage before the S. Typhimurium challenge increased two beneficial genera, Lactobacillus and Bifidobacterium. According to the pathological analysis of ileum, cecum, and serum, temperate or lytic gut phage pretreatment of mice markedly reduced intestinal inflammation, concomitant with lower serum concentration of lipopolysaccharides (LPS) and diamine oxidase (DAO). The oral pretreatments of mice (ST, Lyt, Lys, SM) generally caused an increased expression of IL-113, TNF-alpha, IFN-gamma, IL-4, and IL-10 compared to the matching control. However, in mice pretreated with the lytic phage, the mRNA expression for the pro-inflammatory cytokine TNF-alpha was not significantly higher than that of the control group. No significant differences were detected for peripheral blood B lymphocytes, CD3 +T cells, and the CD4 + /CD8 + ratio in mice pretreated with the lytic and lysogenic phage. This study demonstrated that even lytic phages not targeting the pathogenic serovar Salmonella Typhimurium alleviated intestinal dysbiosis and inflammation in challenged mice.
      原文链接:
    • NSTL
    • Elsevier