Journal of Basic Microbiology最新文献

Two polyhydroxyalkanoate synthase genes, phaC1 and phaC2, were identified in three strains of Cupriavidus malaysiensis (C. malaysiensis): C. malaysiensis USMAA1020^T, C. malaysiensis USMAHM13, and C. malaysiensis USMAA2-4. Interestingly, the genome of C. malaysiensis USMAA1020^T revealed the presence of the polyhydroxyalkanoate granule-associated protein (phaF), which was not present in C. malaysiensis USMAHM13 and C. malaysiensis USMAA2-4. A Maximum Likelihood phylogenetic analysis shows that the phaC genes were classified into Class I synthases. The phaC1 and phaC2 genes in the three C. malaysiensis strains formed a separate, distinct cluster. To further examine the function of phaC, both phaC genes were cloned from C. malaysiensis USMAA1020^T and individually expressed in Cupriavidus necator (C. necator) PHB-4, which serves as a benchmark of functionality for other strains. Using γ-butyrolactone as the sole carbon source, the poly(3-hydroxybutyrate-co-4-hydroxybutyrate) contains up to 83.00 mol% 4-hydroxybutyrate (4HB) and 26.50% PHA content. However, the transformant C. necator PHB-4 with phaC2 produced only 2.30% PHA content and no 4HB monomer. The phaC2 transformant produces up to 100 mol% 3HB monomer and 41.90% PHA content, while the phaC1 transformant produces only 25.80% PHA content when using oleic acid as the sole carbon source. When provided with a mixed substrate of oleic acid and 1-pentanol, the transconjugants accumulated up to 20% PHA content but produced a low 3HV content of only 4%-5%. These findings significantly contribute to the scientific literature by improving the understanding of the genetic and biochemical diversity of the two PHA synthases, phaC1 and phaC2, in Cupriavidus species.

Gemfibrozil (GEM) is a phenoxy aromatic acid-based lipid-lowering drug. It activates peroxisome proliferator-activated receptor alpha (PPAR-α), which leads to altered lipid metabolism and lowers serum triglyceride levels by modulating lipoprotein lipase. However, the action of the mode of GEM is still unclear. Herein, the model organism Saccharomyces cerevisiae was applied to explore the molecular mechanism of GEM regulating lipid metabolism. The results showed that the triacylglycerol (TAG) content and the number of lipid droplets of yeast increased significantly after GEM treatment in the wild-type BY4741. Screening of mutations related to lipid metabolism pathways (PAH1, DGK1, TGL3, TGL4, LRO1, ARE1, ARE2, and DGA1) showed that dgk1Δ had no change in lipid accumulation under GEM. In the wild type, GEM inhibited the expression of DGK1, resulting in a significant decrease in the contents of phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS)) and neutral lipids (TAG and diacylglycerol (DAG)). However, their abundances could not be changed in dgk1Δ after the treatment with GEM Luciferase assay further showed that DGK1 may be a target of GEM to induce lipid accumulation via TUP1/CYC8, which could act on the DGK1 promoter-TATA highly conserved element (-400 bp - 200 bp). Altogether, the effect of GEM on lipid metabolism was associated with the upregulation of TUP1/CYC8, leading to a decrease in the expression of DGK1, thereby increasing the TAG content in yeast cells. It is expected that the data will help to clarify the molecular mechanism of GEM regulating lipid metabolism in humans.

Cover illustration:

Actinomycetes isolated from a metal rich environment in a former uranium mining area near Ronneburg, Thuringia. The strains show high metal resistance.

(Photo: Götz Haferburg, Friedrich-Schiller-University, Jena, Germany)

Chlamydomonas reinhardtii is a promising model microalga for recombinant molecules production. Nonetheless, low yield is a challenge for its industrial use. This work investigated the influence of ammonium chloride (NH₄Cl) concentration and temperature on the growth of transgenic C. reinhardtii expressing the fluorescent protein mCherry on a laboratory scale. A Central Composite Rotatable Design was used to establish the cultivation conditions. NH₄Cl concentrations ranging from 400 to 647.49 mg/L and temperatures between 25°C and 32.1°C resulted in maximum values of cell concentration and mCherry fluorescence. Lower temperatures (15°C-17°C) were found to be more suitable for the accumulation of total soluble proteins. These results demonstrate that cultivation conditions can positively affect C. reinhardtii growth, with a range of conditions that can be used. Unlike genetic approaches, this study provides a solution to enhance both growth and recombinant protein expression in C. reinhardtii. These findings pave the way for scaling up the use of C. reinhardtii as a biofactory in industry and can be applied to other microalgal systems.

The aim of this study was to investigate the production, stability and applicability of dyes produced by filamentous fungi isolated from wood. First, the effect of culture conditions on fungal growth and dye production was investigated. The dyes were experimentally studied for solubility and stability and chemically characterized by FT-IR and UPLC-Q-EXACTIVE-MS. Finally, the dye was used to evaluate its industrial applicability by staining a variety of woods. The results showed that the filamentous fungus Arthrinium phaeospermum was able to produce red water-soluble pigments, which were thermally and ultraviolet stable and remained stable in pH 1-9. Chemical analysis showed that the red dye contained the chromogenic substances bostrycin and about 7.01% of griseofulvin. Dyeing experiments showed that the red dye was able to give the wood a red color and a natural grain. The results of various experiments indicate that A. phaeospermum has the potential to produce dyes for use in the wood dyeing and textile industries.

Biofertilizers are considered as a sustainable solution for promoting the growth and productivity of crops while reducing the dependence on chemical fertilizers. There is a growing need for the sustainable agricultural solutions to lessen the reliance on chemical fertilizers; thus, evaluating Bacillus strains as biofertilizers for cotton growth promotion can support eco-friendly and economically viable crop production. Therefore, the growth promoting potential of endophytic Bacillus altitudinis strain TM22 and B. atrophaeus strain MCM61 applied as soil drenching or seed treatment, was evaluated on cotton cv. 'SS32'. In vitro, the qualitative assay both TM22 and MCM61 showed proteolytic, amylolytic, lipolytic, cellulolytic, and chitinolytic activity. TM22 and MCM61 strains also demonstrated the ability to produce siderophores, indole 3-acetic acid (IAA), and phosphate solubilization. In the pot experiment, seed biopriming with TM22 and MCM61 had better performance regarding plant growth and biomass, photosynthetic pigments, stomatal conductance, and relative leaf water contents than the soil drenching application. The gene expression analysis of growth hormones-related genes demonstrated that TM22 and MCM61 showed an upregulated expression of ARF1, ARF18, EXP6, IAA9, GIB1b, and CKX6 while ERF and ERF17 genes were downregulated. Overall, these findings suggest that seed biopriming with B. altitudinis TM22 and B. atrophaeus MCM61 is an effective method with the potential to enhance the biomass of cotton.

One of the most dangerous characteristics of bacteria is their propensity to form biofilms and their resistance to the drugs used in clinical practice today. The total number of genes that can be categorized as virulence genes ranges from a few hundred to more than a thousand. The bacteria employ a variety of mechanisms to regulate the expression of these genes in a coordinated manner during infection. The search for new agents with anti-virulence capacity is therefore crucial. Nanotechnology provides safe platforms for targeted therapies to combat a broad spectrum of microbial infections. As a new class of innovative materials, carbon-based nanomaterials (CBNs), which include carbon dots, carbon nanotubes, graphene, and fullerenes can have strong antibacterial activity. Exposure to CBNs has been shown to affect bacterial gene expression patterns. This study investigated the effect of CBNs on the repression of specific genes related to bacterial virulence/pathogenicity.

Soil ecosystems consist of diverse microbial communities with great potential for ecological and biotechnological applications. These communities encounter various abiotic stresses, which expedite the activation of transient overexpression of heat shock proteins (HSPs). In the present study, a soil bacterium was isolated and identified as Bacillus licheniformis strain PSK.A1, and its growth parameters were optimized before exposing it to heat, salt, pH, and antibiotic stress conditions. Comparative protein expression was analyzed using SDS-PAGE, protein stabilization via protein aggregation assays, and survival through single spot dilution and colony-counting methods under various stress conditions. The pre-treatment of short stress dosage showed endured overall tolerance of bacterium to lethal conditions, as evidenced by moderately enhanced total soluble intracellular protein content, better protein stabilization, comparatively over-expressed HSPs, and relatively enhanced cell survival. The findings highlighted that cells grown under optimal conditions were more susceptible to lethal environments than stressed cells, with their enhanced tolerance linked to the overexpression of 20 distinct HSPs of 17-91 kD. These insights offer the potential for developing strategies to enhance microbial resilience for various applications including bacterial bioprocessing, bio-remediation, and infectious disease management.

The ash weevil, Myllocerus subfasciatus, is a significant insect pest that infests brinjal. Both the adults and grubs feed on the leaves and roots, respectively, leading to considerable yield loss. The subterranean habits of the larvae limit the effectiveness of insecticide applications, necessitating the implementation of integrated pest management programs that utilize entomopathogenic fungi. This investigation aimed to identify potential Metarhizium species against ash weevil larvae through scanning electron microscopy (SEM) and histopathology. The ash weevils were mass-cultured on brinjal plants under insect-proof conditions. Eleven Metarhizium sourced from the departmental repository were subjected to pathogenicity tests on second-instar ash weevil larvae, revealing that a concentration of 1 × 10⁶ conidia/mL was optimal for SEM and histological studies. Among the 11 Metarhizium strains examined, the TNAU ENTMA TDM 8 strain produced spores measuring 5.8 µm in length and 2.4 µm in width in both potato dextrose agar (PDA) medium and larvae. SEM analysis indicated that the mycelial adherence and penetration of Metarhizium were most pronounced in the larvae 5 days post inoculation (DPI). Histopathological investigations demonstrated that the TNAU ENTMA TDM 8 strain caused degradation of fat bodies and hemocytes at 3 DPI, and complete body distortion at 7 DPI, while the untreated control exhibited no such effects. The M. robertsii strain TNAU ENTMR GYU 1 displayed slower infectivity compared to the M. anisopliae strains. The TNAU ENTMA TDM 8 strain was determined to be the most effective against M. subfasciatus larvae and can be utilized for managing ash weevil populations.