World Journal of Microbiology and Biotechnology最新文献

Stalk rot disease is a major constraint in maize production and till date reported to be caused by two to three species of phytopathogenic fungi but, in our present study, we disclose the first report of stalk rot is caused by complex species of phytopathogens, which belongs to five different genera. Therefore, to substantiate these findings, a total of 105 diseased samples of maize were collected from 21 different locations in six different geographical locations of India from which 48 isolates were used for the research study. Morphological features such as pigmentation, colony color, type of mycelium and pattern of mycelium was examined using macro and microscopic methods. A total of 11 different spp. of pathogens belonging to the five different genera: Fusarium verticillioides (56.25%), F. equiseti (14.5%), F. andiyazi (6.25%), F. solani (2.08%), F. proliferatum (2.08%), F. incarnatum (2.08%), Lasidioplodia theobrame (6.25%), Exserohilum rostrtum (4.16%), Nigrospora spp. (4.16%). and Schizophyllum commune (2.08%) were identified by different housekeeping genes (ITS, TEF-1α, RPB2 and Actin). Fusarium verticillioides, F. equiseti and F. andiyazi were major pathogens involved in stalk rot. This is the first report on F. proliferatum, F. solani, F. incarnatum, Lasidioplodia theobrame, Exserohilum rostrtum, Nigrospora spp. and Schizophyllum commune causing stalk rot of maize and their distribution in the different states of India. Studies on population dynamics of PFSR will enhance the understanding of pathogen behavior, virulence, or its association with different pathogens across India, which will facilitate the development of resistant maize genotypes against the PFSR.

The ability of most opportunistic bacteria to form biofilms, coupled with antimicrobial resistance, hinder the efforts to control widespread infections, resulting in high risks of negative outcomes and economic costs. Endolysins are promising compounds that efficiently combat bacteria, including multidrug-resistant strains and biofilms, without a low probability of subsequent emergence of stable endolysin-resistant phenotypes. However, the details of antibiofilm effects of these enzymes are poorly understood. To elucidate the interactions of bacteriophage endolysins LysAm24, LysAp22, LysECD7, and LysSi3 with bacterial films formed by Gram-negative species, we estimated their composition and assessed the endolysins’ effects on the most abundant exopolymers in vitro. The obtained data suggests a pronounced efficiency of these lysins against biofilms with high (Klebsiella pneumoniae) and low (Acinetobacter baumannii) matrix contents, or dual-species biofilms, resulting in at least a twofold loss of the biomass. These peptidoglycan hydrolases interacted diversely with protective compounds of biofilms such as extracellular DNA and polyanionic carbohydrates, indicating a spectrum of biofilm-disrupting effects for bacteriolytic phage enzymes. Specifically, we detected disruption of acid exopolysaccharides by LysAp22, strong DNA-binding capacity of LysAm24, both of these interactions for LysECD7, and neither of them for LysSi3.

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Bacterial extracellular vesicles (BEVs) are non-replicative nanostructures released by Gram-negative and Gram-positive bacteria as a survival mechanism and inter- and intraspecific communication mechanism. Due to BEVs physical, biochemical, and biofunctional characteristics, there is interest in producing and using them in developing new therapeutics, vaccines, or delivery systems. However, BEV release is typically low, limiting their application. Here, we provide a biotechnological perspective to enhance BEV production, highlighting current strategies. The strategies include the production of hypervesiculating strains through gene modification, bacteria culture under stress conditions, and artificial vesicles production. We discussed the effect of these production strategies on BEVs types, morphology, composition, and activity. Furthermore, we summarized general aspects of BEV biogenesis, functional capabilities, and applications, framing their current importance and the need to produce them in abundance. This review will expand the knowledge about the range of strategies associated with BEV bioprocesses to increase their productivity and extend their application possibilities.

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Biological control using edible mushrooms as natural enemies is a sustainable alternative for pest management. Despite the well-established literature on toxins and secondary metabolites produced by these fungi in the biochemical control of nematodes, the nematicidal activity of proteases from different Pleurotus species is yet to be investigated. Therefore, this study aimed to correlate protease to the nematicidal activity of different mushrooms, Pleurotus sp., P. ostreatus (SB), P. ostreatus (Pearl), and P. djamor. For such a purpose, we performed motility assays of Panagrellus sp. at different time intervals, 6, 12, and 24 h for each of the mushrooms. In addition, the protease activity was measured using different pH (5, 7, and 9) and fermentation time intervals (45 and 75 days). Furthermore, we also evaluated the effect of this cell-free extract on Panagrellus sp. In response to these experiments, all edible mushrooms showed a reduction over 82% for the nematode-feeding activity (p < 0.01). The cell-free crude extract of each of the fungi studied showed nematocidal activity (p < 0.01). For the 45-day fermentation, P. djamor exhibited statistical significance (p < 0.01) compared with the others, reaching a reduction percentage of 73%. For the 75-day fermentation, Pleurotus sp. and P. ostreatus (Pearl) showed significant differences compared with the other fungi (p < 0.01), with reduction percentages of 64 and 62%, respectively. Herein, protease activity was associated with the nematicidal action of different Pleurotus species in controlling Panagrellus sp.

The aim of this study was to investigate the mechanisms by which yeasts (Saccharomyces cerevisiae) control the toxic effects of aflatoxins, which are not yet fully understood. Radiolabeled aflatoxin B₁ (AFB₁³H) was administered by gavage to Wistar rats fed with aflatoxin (AflDiet) and aflatoxin supplemented with active dehydrated yeast Y904 (AflDiet + Yeast). The distribution of AFB₁³H and its metabolites were analyzed at 24, 48 and 72 h by tracking back of the radioactivity. No significant differences were observed between the AflDiet and AflDiet + Yeast groups in terms of the distribution of labeled aflatoxin. At 72 h, for the AflDiet group the radiolabeled aflatoxin was distributed as following: feces (79.5%), carcass (10.5%), urine (1.7%), and intestine (7.4%); in the AflDiet + Yeast the following distribution was observed: feces (76%), carcass (15%), urine (2.9%), and intestine (4.9%). These values were below 1% in other organs. These findings indicate that even after 72 h considerable amounts of aflatoxins remains in the intestines, which may play a significant role in the distribution and metabolism of aflatoxins and its metabolites over time. The presence of yeast may not significantly affect this process. Furthermore, histopathological examination of hepatic tissues showed that the presence of active yeast reduced the severity of liver damage caused by aflatoxins, indicating that yeasts control aflatoxin damage through biochemical mechanisms. These findings contribute to a better understanding of the mechanisms underlying the protective effects of yeasts against aflatoxin toxicity.

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Anthranilic acid (AA) holds significant importance in the chemical industry. It serves as a crucial building block for the amino acid tryptophan by manipulating the tryptophan biosynthesis pathway, it is possible to increase the production of anthranilic acid. In this study, we utilized metabolic engineering approaches to produce anthranilic acid from the halophilic bacterium Virgibacillus salarius MML1918. The halophilic bacteria were grown in an optimized production medium, and mass production of secondary metabolites was made in ATCC medium 1097 Proteose peptone—for halophilic bacteria and subjected to column chromatography followed by sub-column chromatography the single band for the purified compound was confirmed. Further, various spectral analyses were made for the partially purified compounds, and fluorescence microscopy for fungal cell observation was performed. The purified compound was confirmed by single crystal X-ray diffraction (XRD) analysis, and it was identified as 2-amino benzoic acid. The Fourier transform infrared Spectroscopy (FT-IR) spectrum and nuclear magnetic resonance (NMR) spectrum also confirm the structural characteristic of 2-amino benzoic acid. The UV–Vis absorption spectrum of AA shows the maximum absorption at 337.86 nm. The emission spectrum of 2-amino benzoic acid showed the maximum emission at 453 nm. The bio-imaging application of 2-amino benzoic acid was examined with fungal mycelium of Rhizoctonia solani. It was effectively bound and emitted the blue color at the concentration of 200 and 300 µg/mL. The halophilic bacterium (V. salarius), may have unique metabolic pathways and requirements compared to non-halophilic organisms, to produce AA effectively. This could have implications for industrial biotechnology, particularly in manufacturing environments where high salt concentrations are present and also it can be used as bio-imaging agent.

A histidine acid phosphatase (HAP) (PhySc) with 99.50% protein sequence similarity with PHO5 from Saccharomyces cerevisiae was expressed functionally with the molecular mass of ∼110 kDa through co-expression along with the set of molecular chaperones dnaK, dnaJ, GroESL. The purified HAP illustrated the optimum activity of 28.75 ± 0.39 U/mg at pH 5.5 and 40 ˚C. The K_m and K_cat values towards calcium phytate were 0.608 ± 0.09 mM and 650.89 ± 3.6 s^− 1. The half-lives (T_1/2) at 55 and 60 ˚C were 2.75 min and 55 s, respectively. The circular dichroism (CD) demonstrated that PhySc includes 30.5, 28.1, 21.3, and 20.1% of random coils, α-Helix, β-Turns, and β-Sheet, respectively. The T_m recorded by CD for PhySc was 56.5 ± 0.34˚C. The molecular docking illustrated that His59 and Asp322 act as catalytic residues in the PhySc. MD simulation showed that PhySc at 40 ˚C has higher structural stability over those of the temperatures 60 and 80 ˚C that support the thermodynamic in vitro investigations. Secondary structure content results obtained from MD simulation indicated that PhySc consists of 34.03, 33.09, 17.5, 12.31, and 3.05% of coil, helix, turn, sheet, and helix310, respectively, which is almost consistent with the experimental results.

Obesity is a growing epidemic worldwide. Several pharmacologic drugs are being used to treat obesity but these medicines exhibit side effects. To find out the alternatives of these drugs, we aimed to assess the probiotic properties and anti-obesity potentiality of a lactic acid bacterium E2_MCCKT, isolated from a traditional fermented rice beverage, haria. Based on the 16S rRNA sequencing, the bacterium was identified as Lactiplantibacillus plantarum E2_MCCKT. The bacterium exhibited in vitro probiotic activity in terms of high survivability in an acidic environment and 2% bile salt, moderate auto-aggregation, and hydrophobicity. Later, E2_MCCKT was applied to obese mice to prove its anti-obesity potentiality. Adult male mice (15.39 ± 0.19 g) were randomly divided into three groups (n = 5) according to the type of diet: normal diet (ND), high-fat diet (HFD), and HFD supplemented with E2_MCCKT (HFT). After four weeks of bacterial treatment on the obese mice, a significant reduction of body weight, triglyceride, and cholesterol levels, whereas, improvements in serum glucose levels were observed. The bacterial therapy led to mRNA up-regulation of lipolytic transcription factors such as peroxisome proliferator-activated receptor-α which may increase the expression of fatty acid oxidation-related genes such as acyl-CoA oxidase and carnitine palmitoyl-transferase-1. Concomitantly, both adipocytogenesis and fatty acid synthesis were arrested as reflected by the down-regulation of sterol-regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase genes. In protein expression study, E2_MCCKT significantly increased IL-10 expression while decreasing pro-inflammatory cytokine (IL-1Ra and TNF-α) expression. In conclusion, the probiotic Lp. plantarum E2_MCCKT might have significant anti-obesity effects on mice.

Rice straw burning annually (millions of tons) leads to greenhouse gas emissions, and an alternative solution is producing humic acid with high added-value. This study aimed to examine the influence of a microbial consortium and other additives (chicken manure, urea, olive mill waste, zeolite, and biochar) on the composting process of rice straw and the subsequent production of humic acid. Results showed that among the fungal species, Thermoascus aurantiacus exhibited the most prominent impact in expediting maturation and improving compost quality, and Bacillus subtilis was the most abundant bacterial species based on metagenomics analysis. The highest temperature, C/N ratio reduction, and amount of humic acid production (Respectively in lab 61 °C, 54.67%, 298 g kg⁻¹ and in pilot level 65 °C, 72.11%, 310 g kg⁻¹) were related to treatments containing these microorganisms and other additives except urea. Consequently, T. aurantiacus and B. subtilis can be employed on an industrial scale as compost additives to further elevate quality. Functional analysis showed that the bacterial enzymes in the treatments had the highest metabolic activities, including carbohydrate and amino acid metabolism compared to the control. The maximum enzymatic activities were in the thermophilic phase in treatments which were significantly higher than that in the control. The research emphasizes the importance of identifying and incorporating enzymatically active strains that are suitable for temperature conditions, alongside the native strains in decomposing materials. This strategy significantly improves the composting process and yields high-quality humic acid during the thermophilic phase.

Mannan is a predominant constituent of cork hemicellulose and is widely distributed in various plant tissues. β-Mannanase is the principal mannan-degrading enzyme, which breaks down the β-1,4-linked mannosidic bonds in mannans in an endo-acting manner. Microorganisms are a valuable source of β-mannanase, which exhibits catalytic activity in a wide range of pH and temperature, making it highly versatile and applicable in pharmaceuticals, feed, paper pulping, biorefinery, and other industries. Here, the origin, classification, enzymatic properties, molecular modification, immobilization, and practical applications of microbial β-mannanases are reviewed, the future research directions for microbial β-mannanases are also outlined.