Journal of Basic Microbiology最新文献

Bacillus cereus group produces diverse antimicrobial compounds through different metabolic pathways, including amino acid-based compounds, sugar derivatives, volatile and miscellaneous compounds. These antimicrobial compounds exhibit antibacterial and antifungal activities against various plant pathogens, promoting plant growth and enhancing tolerance to abiotic stresses. They also exhibit nematicidal activities against plant nematodes and antagonistic effects against pathogens in aquatic animals, promoting growth and inducing immune responses. Moreover, B. cereus group bacteria play a significant role in bioremediation by breaking down or neutralizing environmental pollutants, such as plastics, petroleum products, heavy metals, and insecticides. They produce enzymes like laccases, lipases, proteases, and various oxidases, contributing to the degradation of these pollutants. In the food industry, they can cause food poisoning due to their production of enterotoxins. However, they are also utilized in various industrial applications, such as producing environmentally friendly bio-based materials, biofertilizers, and nanoparticles. Notably, B. cereus transforms selenite into selenium nanoparticles, which have health benefits, including cancer prevention. In summary, B. cereus group bacteria have diverse applications in agriculture, bioremediation, industry, and medicine, contributing to sustainable and eco-friendly solutions across multiple fields. In this review, we have revised B. cereus group and the characteristics of every species; we have also highlighted the more important compounds secreted by the species of B. cereus group and the applications of these compounds. The aim is to explain the available secondary metabolites to classify the species from this group, increasing the knowledge about taxonomy of this group.

The enzyme catechol 1,2-dioxygenase (CAT) plays a critical role in the biosynthesis pathway of cis, cis-muconic acid (CCMA), which serves as an indispensable raw material for various industrial applications. In this research, we cloned a novel cold-adapted CAT (HaCAT) from the Antarctic sea ice bacterium Halomonas sp. ANT108. Homology modeling analysis revealed that HaCAT possessed the characteristic Fe³⁺ binding site and catalytic active site of typical CATs, and it exhibited unique structural adaptations to cold environments. The optimal temperature and pH for recombinant HaCAT (rHaCAT) were found to be 25°C and 6.5, respectively. At 0°C, the enzyme retained a maximum activity of 43.6%, and in the presence of 1.0 M NaCl, its activity reached 173.9%, demonstrating significant salt tolerance. Additionally, the V_max and K_m of rHaCAT were 6.68 μmol/min/mg and 128.90 μM at 25°C, respectively. Furthermore, rHaCAT was successfully immobilized in the metal-organic framework ZIF-8 and retained almost 50% of its activity after five reuse cycles, demonstrating excellent reusability. Overall, these results provided a new resource and theoretical foundation for the industrial biocatalytic production and modification of CAT.

Given the benefits of bacteria associated with the rhizosphere and phytoplane of halophytes, this research focused on examining the plant growth-promoting characteristics of bacteria isolated from Cressa cretica, Suaeda aegyptiaca, and Alhagi graecorum. From the 33 isolates tested, 9 exhibited plant growth-promoting traits. Bacillus rugosus strain CS5 and Bacillus sp. strain SS4 exhibited the notable growth inhibition of the pathogenic fungus Fusarium oxysporum, with values of 47% and 45%, respectively. Bacillus sp. strains SS4 and CS1 demonstrated impressive results in solubilizing phosphorus and zinc, respectively, achieving concentrations of 259 and 271 mg L^-1. Additionally, Staphylococcus xylosus strain SR2, Bacillus sp. strain SS4, and Bacillus paralicheniformis strain CR1 thrived in nitrogen-free media. The Priestia filamentosa strain AL4 showed the greatest HCN production, whereas B. paralicheniformis strain CR1 was notable for higher auxin production. The Bacillus sp. strains SS4 and CS1 exhibited greater tolerance than other isolates in a medium containing 600 mM of NaCl. Additionally, inoculating these isolates into soil significantly alleviated the salinity and drought stress on Zea mays seedlings. These findings suggest that further investigation into these strains as microbial inoculants could be beneficial for mitigating salt and drought stress in plants.

In situ biosurfactant production by hydrocarbon degrader microorganisms is an attractive approach in the bioremediation of oil contamination because of their compatibility, biodegradability, environmental safety, and stability under extreme environmental conditions. Given the high efficiency of bacteria in degrading petroleum hydrocarbons, the present work studied the detection and characterization of a biosurfactant-producing hydrocarbon degrader, Roseomonas aestuarii NB833. This strain was able to synthesize a biosurfactant during the biodegradation of crude oil, which reduced the surface tension of the aqueous system from 70 to 34 mN m^-1, with a critical micelle concentration of 200 mg L^-1. The emulsification ability of the biosurfactant was sustained at various temperatures, pH values, and salinities. The biosurfactant chemical structure was identified via FT-IR, LC-MS, and NMR analyses. These analyses confirmed the production of surfactin-C14 with a molecular mass of 1007 g mol^-1. These results revealed the high potential of R. aestuarii NB833 as an in situ surfactin-producing bacteria for bioremediation applications under extreme environmental conditions.

Monascus is a widely used natural microorganism in our country, which can produce useful secondary metabolites. Studies have shown that the nitrogen source directly affects the growth, reproduction, and secondary metabolites of Monascus. As a global transcriptional regulator of nitrogen metabolism, MareA gene is involved in the regulation of secondary metabolism. In this study, we found the MareA gene that is highly homologous to the AreA gene sequence, and used MareA to obtain ΔMareA and OE-MareA. Three strains were cultured with glutamine, urea, NaNO₃, and (NH₄)₂SO₄ nitrogen sources. The Monascus pigments and related genes were analyzed by solid-state fermentation under different nitrogen sources. The results showed that the pigment production of the ΔMareA decreased, but the OE-MareA did the opposite. The secondary metabolites of the three strains were analyzed by HPLC and expression level of pigment biosytnthesis gene was determined by RT-qPCR. The relative expression levels of four key Monascus pigment genes in ΔMareA were significantly upregulated in mppE gene, but downregulated in MpPKS5, mppG, and mppD genes. Monascus pigment genes were increased in OE-MareA. In terms of growth regulation, the expression of VosA and LaeA genes was significantly reduced in ΔMareA, while OE-MareA significantly promoted the expression of GprD genes. The pigment production and gene expression in ΔMareA were significantly lower than that of C100, while the opposite was true of OE-MareA when NaNO₃ was added to the culture medium. In conclusion, MareA gene had different regulatory effects on Monascus growth and pigments metabolism under different nitrogen sources.

Polyamines are organic and aliphatic molecules essential for the growth, development, and survival of both eukaryotes and prokaryotes. In fungi, polyamines play a crucial role in cellular differentiation and pathogenesis. Since fungi and animals are closely related evolutionarily, and fungi can be easily genetically manipulated in the lab, they serve as excellent models for studying polyamine metabolism and the molecular mechanisms controlled by these biomolecules. Although the metabolism of polyamines has been extensively studied in model fungi such as Saccharomyces cerevisiae and Ustilago maydis, the conservation of the polyamine biosynthesis pathway in other Ustilaginomycetes, a class of fungi that includes phytopathogens, saprophytes, mutualists, and mycorrhizae, has not been thoroughly investigated. In this study, using a genomic and bioinformatics approach, we analyzed the conservation of the polyamine biosynthesis pathway in Ustilaginomycetes. Additionally, we confirmed the functional conservation of ornithine decarboxylase (Odc), which is involved in the synthesis of putrescine, one of the most important polyamines in fungi and complex multicellular eukaryotic organisms, using genetics and molecular biology tools. Moreover, we identified the differentially regulated genes by this polyamine in U. maydis. This research provides insights into the similarities and differences in the conservation of the polyamine biosynthesis pathway in fungi, and it expands our understanding of the role of polyamines and the mechanisms regulated by these molecules in eukaryotes.

Tomato (Solanum lycopersicum) and chilli (Capsicum annuum) are globally significant vegetable crops susceptible to damping-off disease caused by Pythium aphanidermatum, leading to substantial yield losses. The study aimed to document the biocontrol and plant growth promotion potential of Streptomyces rochei against damping-off disease in tomato and chilli. The actinobacterial isolates ACS18 followed by ACT30, and AOE12 were accomplished as the most effective antagonists against P. aphanidermatum in vitro. Molecular characterization confirmed these isolates as members of Streptomyces genus, with ASH 18 the top performer identified as S. rochei isolate. Analysis of biomolecule through GC-MS during ditrophic interaction between pathogen and S. rochei showed the presence of various antifungal metabolites which were directly related to suppression of the pathogen. Subsequently, S. rochei was formulated into a talc-based preparation and used as seed treatment and soil application against damping-off. In greenhouse trials, significant reductions in damping-off incidence were observed, Furthermore, seedlings treated with S. rochei displayed enhanced root and shoot lengths compared to the uninoculated controls. These benefits potentiate S. rochei as a promising biocontrol agent and demonstrating its dual benefits of disease suppression and promotion of seedling growth.

Carotenoid, natural pigments, synthesized by plants and microbes are now much favored in global markets due to the awareness of their putative health benefits, and a wide array of commercial applications. There is a diversity of natural and synthetic carotenoid, but only a few of them are commercially produced, including carotenes (β-carotene and lycopene) and xanthophylls (astaxanthin, canthaxanthin, lutein, zeaxanthin, and capsanthin). However, for commercial production, plants and algae are more favored than cyanobacteria because of their much less carotenoid synthesis than land plants; although they are well known for producing commercially important carotenoid. But with advances in optimization of their carotenoid production, cyanobacteria can be used as a potential source of carotenoid production in the future allowing us to exploit its various applications. Hence, this study investigated the effects of pH and light conditions on carotenoid production in the sub-aerial cyanobacterium Desertifilum dzianense ON358232.1. The results revealed that the highest carotenoid synthesis occurred under alkaline conditions (pH 9) and red-light exposure, significantly increasing compared to the control (pH 7.2, white light). UV-Vis and FTIR analyses confirmed the presence of β-carotene as the primary carotenoid, demonstrating strong antioxidant potential. The study's findings highlight the optimal environmental parameters for enhancing carotenoid yield, which can be applied for industrial and pharmaceutical uses due to their antioxidant properties.

Shiitake mushrooms (Lentinula edodes) hold significant cultural and economic value, particularly in Asia where they are extensively cultivated. The diversification of shiitake cultivars, driven by the need to adapt to various climatic conditions and cultivation methods, has resulted in over 200 distinct cultivars. Reliable identification of these cultivars is crucial for breeding, intellectual property protection, and effective genetic resource management. Traditional morphological methods are inadequate due to their subjectivity and labor-intensive nature. This study leverages nanopore high-throughput sequencing to comprehensively analyze the rDNA regions (SSU, ITS, LSU, IGS) of 41 shiitake strains from Taiwan's Bioresource Collection and Research Center (BCRC), comprising 5 wild strains, 33 commercial strains, and 3 wild-commercial hybrids. Our results identified the IGS1 region as the most variable and suitable for cultivar differentiation. Consequently, we developed an interactive online database (https://github.com/Raingel/ShiitakeIGS1) that integrates 317 IGS1 sequences from Taiwan, Japan, and China. This platform allows users to upload their IGS1 sequences and identify similar cultivars through a user-friendly interface, enhancing the precision and efficiency of shiitake cultivar identification.