World journal of microbiology & biotechnology最新文献

Trichoderma spp. is primarily applied to manage biotic stresses in plants. Still, they also can mitigate abiotic stresses by the stimulation of antioxidative protective mechanisms and enhanced synthesis of secondary metabolites. The study optimized the conditions to enhance peptaibol production by novel Trichoderma spp, characterized and quantified peptaibol- alamethicin using HPLC and LC MS-MS. The present study investigated these isolates efficacy in enhancing growth and the associated physio-biochemical changes in black pepper plants under moisture stress. Under in vitro conditions, out of 51 isolates studied, six isolates viz., T. asperellum (IISR NAIMCC 0049), T. erinaceum (IISR APT1), T. harzianum (IISR APT2), T. harzianum (IISR KL3), T. lixii (IISR KA15) and T. asperellum (IISR TN3) showed tolerance to low moisture levels (5, 10 and 20%) and higher temperatures (35 and 40 °C). In vivo evaluation on black pepper plants maintained under four different moisture levels (Field capacity [FC]; 75%, 50%, and 25%) showed that the plants inoculated with Trichoderma accumulated greater quantities of secondary metabolites viz., proline, phenols, MDA and soluble proteins at low moisture levels (50% and 25% FC). In the present study, plants inoculated with T. asperellum and T. harzianum showed significantly increased growth compared to uninoculated plants. The shortlisted Trichoderma isolates exhibited differences in peptaibol production and indicated that the peptide might be the key factor for their efficiency as biocontrol agents. The present study also demonstrated that Trichoderma isolates T. harzianum and T. asperellum (IISR APT2 & NAIMCC 0049) enhanced the drought-tolerant capabilities of black pepper by improving plant growth and secondary metabolite production.

Extracellular proteases from haloarchaea, also referred to as halolysins, are in increasing demand and are studied for their various applications in condiments and leather industries. In this study, an extracellular protease encoding gene from the haloarchaeon Halorubellus sp. PRR65, hly65, was cloned and heterologously expressed in E. coli. The novel halolysin Hly65 from the genus Halorubellus was characterized by complete inhibition of phenylmethanesulfonyl fluoride (PMSF) on its enzyme activity. Experimental determination revealed a triad catalytic active center consisting of Asp¹⁵⁴-His¹⁹³-Ser³⁴⁸. Deletion of the C-terminal extension (CTE) resulted in loss of enzyme activity, while dithiothreitol (DTT) did not inhibit the enzyme activity, suggesting that Hly65 may function as a monomer. The K_m, V_max and K_cat for the Hly65 were determined to be 2.91 mM, 1230.47 U·mg^-1 and 1538.09 S^-1, respectively, under 60 °C, pH 8.0 and 4.0 M NaCl using azocasecin as a substrate. Furthermore, a three-dimensional structure prediction based on functional domains was obtained in this study which will facilitate modification and reorganization of halolysins to generate mutants with new physiological activities.

The use of biosurfactants represents a promising technology for remediating hydrocarbon pollution in the environment. This study evaluated a highly effective biosurfactant strain-Bacillus cereus GX7's ability to produce biosurfactants from industrial and agriculture organic wastes. Bacillus cereus GX7 showed poor utilization capacity for oil soluble organic waste but effectively utilized of water- soluble organic wastes such as starch hydrolysate and wheat bran juice as carbon sources to enhance biosurfactant production. This led to significant improvements in surface tension and emulsification index. Corn steep liquor was also effective as a nitrogen source for Bacillus cereus GX7 in biosurfactant production. The biosurfactants produced by strain Bacillus cereus GX7 demonstrated a remediation effect on oily beach sand, but are slightly inferior to chemical surfactants. Inoculation with Bacillus cereus GX7 (70.36%) or its fermentation solution (94.38%) effectively enhanced the degradation efficiency of diesel oil in polluted seawater, surpassing that of indigenous degrading bacteria treatments (57.62%). Moreover, inoculation with Bacillus cereus GX7's fermentation solution notably improved the community structure by increasing the abundance of functional bacteria such as Pseudomonas and Stenotrophomonas in seawater. These findings suggest that the Bacillus cereus GX7 as a promising candidate for bioremediation of petroleum hydrocarbons.

Brevibacillus brevis FJAT-0809-GLX has a broad spectrum of antimicrobial activity. Understanding the molecular basis of biocontrol ability of B. brevis will allow us to develop effective microbial agents for sustainable agriculture. In this study, we present the complete and annotated genome sequence of FJAT-0809-GLX. The complete genome size of B. brevis FJAT-0809-GLX was 6,137,019 bp, with 5688 predicted coding sequences (CDS). The average GC content of 47.38%, and there were 44 copies of the rRNAs operon (16S, 23S and 5S RNA), and 127 tRNA genes. A total of 11,162 genes were functionally annotated with the COG, GO, and KEGG databases, and 123 genes belonged to CAZymes. Genomic secondary metabolite analysis indicated 13 clusters encoding potential new antimicrobials. FJAT-0809-GLX was designated as B. brevis according to average nucleotide polymorphism (ANI) and phylogenetic analysis. The pangenome consisted of 7141 homologous genes, and 4469 homologous genes shared by B. brevis FJAT-0809-GLX, B. brevis NBRC100599, B. brevis DSM30, and B. brevis NCTC2611. The number of unique homologous genes of B. brevis FJAT-0809-GLX (419 genes) and B. brevis NBRC100599 (480 genes) were much more than those in B. brevis DSM30 (13 genes), and B. brevis NCTC2611 (6 genes). Nine gene clusters encoding for secondary metabolite biosynthesis were compared in the genome of B. brevis FJAT-0809-GLX with those of B. brevis NBRC100599, B. brevis DSM30 and B. brevis NCTC2611, and the gene clusters encoding for lantipeptide and transatpks-otherks only existed in genome of B. brevis FJAT-0809-GLX. The 11 BbPks genes were included in the B. brevis FJAT-0809-GLX genome, which contained the conserved PS-DH domain. The relative expression of BbPksL, BbPksM2, BbPksM3, BbPksN3, BbPksN4 and BbPksN5 reached a maximum at 120 h and then decreased at 144 h. Our results provided detailed genomic and Pks genes information for the FJAT-0809-GLX strain, and lid a foundation for studying its biocontrol mechanisms.

Outer membrane vesicles (OMVs) are nano-sized vesicles actively released by Gram-negative bacteria, playing a crucial role in bacterial survival and interactions with phages. This review focuses on OMVs and succinctly delineates the stimuli instigating OMV formation, their functional repertoire, and their involvement in bacterial-phage interplays. Initially, the discussion centers on the drivers prompting OMV genesis, encompassing both extrinsic environmental pressures and intrinsic regulatory mechanisms within bacterial systems. Subsequently, a comprehensive examination of OMVs' multifaceted functions in bacterial physiology ensues, spanning signaling cascades, nutrient transport, antibiotic resilience, and evasion of immune surveillance. Particular emphasis is placed on elucidating the paramount significance of OMVs in mediating bacterial-phage dynamics. OMVs function as decoys, providing protection to bacterial hosts against phages, and concurrently promoting the spread of phage receptors, thereby rendering phage-resistant strains susceptible to phage invasion. This comprehensive review deepens our comprehension of membrane vesicles biogenesis in bacteria and their pivotal role in microbial community dynamics.

Fusing insect derived neurotoxic peptides with Galanthus nivalis agglutinin (GNA) has been shown to enhance the insecticidal activity of the neuropeptides, especially when administered orally. This study produced a recombinant scorpion insect specific neurotoxin BjαIT, GNA, and a fusion protein BjαIT/GNA using Pichia pastoris as an expression host. Recombinant rBjαIT/GNA was found to be easily degraded during expression in yeast which and produced a main protein product with a molecular weight of approximately 14 kDa. Cytotoxicity results showed that rBjαIT, rGNA, and rBjαIT/GNA had no toxicity to mammalian NIH/3T3 cells. Adding rBjαIT or rBjαIT/GNA at a concentration as low as 1 ng/mL to insect cell culture medium inhibited the proliferation of insect Sf9 cells, with rBjαIT exhibiting stronger cytotoxicity, while 20 ng/mL rGNA did not inhibit the proliferation of Sf9 cells. Silkworm larval injection results showed that rBjαIT/GNA was the most toxic of the three proteins, followed by rBjαIT, and rGNA. When rBjαIT/GNA was injected at a concentration of 0.129 nmol/g body weight 46.7% of silkworm died within 48 h. Feeding newly hatched silkworms with rBjαIT/GNA at a leaf surface concentration of 40 µg/cm² resulted in 76.7% mortality within 24 h. However, rBjαIT/GNA showed almost no oral insecticidal activity against second instar silkworms. The results indicated that rBjαIT/GNA has stronger injection insecticidal activity and feeding insecticidal activity than rBjαIT and rGNA individually, making it more suitable for biological control.

Trichoderma longibrachiatum UN32 is a well-documented mutant strain known to produce dendrobine-type total alkaloids (DTTAs). It was serendipitously observed that the addition of Co²⁺ to the medium resulted in a notable enhancement in DTTAs production in the T. longibrachiatum UN32 strain, accompanied by an upregulating effect on the expression of antioxidase-related genes. Hence, the objective of the present work was to ascertain whether ROS (intracellular levels of hydrogen peroxide) induced by Co²⁺ treatment has a beneficial or detrimental impact on DTTAs biosynthesis. A comparison of the intracellular levels of hydrogen peroxide (H₂O₂) and DTTAs treated with CoCl₂ and CH₃COOH revealed that CoCl₂ was the optimal inducer for investigating the relationship between ROS formation and DTTAs production. This was due to the observation that ROS formation was reduced by approximately 4% and DTTAs production was increased by 12.55% in comparison to the CH₃COOH treatment. The physiological results revealed that the introduction of Co²⁺ resulted in the oxidative damage and activation of the expression of intracellular superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Furthermore, it was confirmed that ROS induced by Co²⁺ was beneficial to DTTAs production by adding exogenous ROS scavengers. The inclusion of all ROS scavengers, including vitamin C, tocopherol, melatonin, mannitol, and sesamol, resulted in a reduction in ROS accumulation and a concomitant decrease in DTTAs production. Specifically, the addition of melatonin at a concentration of 0.4 mg/L demonstrated significant effects, resulting in a 32.53% (P < 0.01) decrease in ROS accumulation and a 45.22% (P < 0.01) reduction in DTTAs production. Subsequently, the timelines of accumulation of intracellular H₂O₂ and DTTAs content indicated that ROS are also crucial for normal fermentation without CoCl₂ addition. Specifically, the proper H₂O₂ dose for DTTAs accumulation is between 8.82 and 18.86 μmol/g. The present study offers the initial experimental evidence indicating that CoCl₂ enhance DTTAs production during the culture of T. longibrachiatum UN32 via leading an increase in intracellular ROS, which is conductive to DTTAs production and can be inhibited by the ROS scavengers. Our results provide insights into the mechanistic study of DTTAs biosynthesis.

An animal charcoal contaminated cottage industry soil in Lagos, Nigeria (ACGT) was compared in an ex post facto study with a nearby unimpacted soil (ACGC). Hydrocarbon content was higher than regulatory limits in ACGT (180.2 mg/kg) but lower in ACGC (19.28 mg/kg). Heavy metals like nickel, cadmium, chromium and lead were below detection limit in ACGC. However, all these metals, except cadmium, were detected in ACGT, but at concentrations below regulatory limits. Furthermore, copper (253.205 mg/kg) and zinc (422.630 mg/kg) were above regulatory limits in ACGT. Next generation sequencing revealed that the procaryotic community was dominated by bacteria in ACGC (62%) while in ACGT archaea dominated (76%). Dominant phyla in ACGC were Euryarchaeota (37%), Pseudomonadota (16%) and Actinomycetota (12%). In ACGT it was Euryarchaeota (76%), Bacillota (9%), Pseudomonadota (7%) and Candidatus Nanohaloarchaeota (5%). Dominant Halobacteria genera in ACGT were Halobacterium (16%), Halorientalis (16%), unranked halophilic archaeon (13%) Salarchaeum (6%) and Candidatus Nanohalobium (5%), whereas ACGC showed greater diversity dominated by bacterial genera Salimicrobium (7%) and Halomonas (3%). Heavy metals homeostasis genes, especially for copper, were fairly represented in both soils but with bacterial taxonomic affiliations. Sites like ACGT, hitherto poorly studied and understood, could be sources of novel bioresources.

Istamycins (ISMs) are 2-deoxyfortamine-containing aminoglycoside antibiotics (AGAs) produced by Streptomyces tenjimariensis ATCC 31603 with broad-spectrum bactericidal activities against most of the clinically relevant pathogens. Therefore, this study aimed to statistically optimize the environmental conditions affecting ISMs production using the central composite design (CCD). Both the effect of culture media composition and incubation time and agitation rate were studied as one factor at the time (OFAT). The results showed that both the aminoglycoside production medium and the protoplast regeneration medium gave the highest specific productivity. Results also showed that 6 days incubation time and 200 rpm agitation were optimum for their production. A CCD quadratic model of 17 runs was employed to test three key variables: initial pH, incubation temperature, and concentration of calcium carbonate. A significant statistical model was obtained including, an initial pH of 6.38, incubation temperature of 30 ˚C, and 5.3% CaCO₃ concentration. This model was verified experimentally in the lab and resulted in a 31-fold increase as compared to the unoptimized conditions and a threefold increase to that generated by using the optimized culture media. To our knowledge, this is the first report about studying environmental conditions affecting ISM production as OFAT and through CCD design of the response surface methodology (RSM) employed for statistical optimization. In conclusion, the CCD design is an effective tool for optimizing ISMs at the shake flask level. However, the optimized conditions generated using the CCD model in this study should be scaled up in a fermenter for industrial production of ISMs by S. tenjimariensis ATCC 31603 considering the studied environmental conditions that significantly influence the production proces.

This research propounds an innovative technology focused on sustainability to increase the biomass yield of Akkermansia muciniphila, the next-generation probiotic, using prebiotic sources to replace or reduce animal mucin levels. A series of experimental design approaches were developed aiming to optimize the growth of Akkermansiamuciniphila by incorporating extracts of green leafy vegetables and edible mushroom into the cultivation media. Experiments using kale extract (KE), Brassica oleracea L., associated with lyophilized mushroom extract (LME) of Pleurotus ostreatus were the most promising, highlighting the assays with 0.376% KE and 0.423% LME or 1.05% KE and 0.5% LME, in which 3.5 × 10¹⁰ CFU (Colony Forming Units) mL^- 1 was achieved - higher than in experiments in optimized synthetic media. Such results enhance the potential of using KE and LME not only as mucin substitutes, but also as a source to increase Akkermansia muciniphila biomass yields and release short-chain fatty acids. The work is relevant to the food and pharmaceutical industries in the preparation of the probiotic ingredient.