Journal of Basic Microbiology最新文献

Aspergillus cristatus is a dominant fungus formed during the "flowering" process of Fuzhuan brick tea. Previous research has established that the sporulation of Aspergillus nidulans, a model organism of filamentous fungi, is regulated by light. However, the sporulation of A. cristatus is dependent on osmotic stress. In a previous study, we used pull-down and mass spectrometry to identify proteins that interacted with AcHog1 in A. cristatus when cultured under different conditions of osmotic stress. In the present study, we analyzed the proteins we identified previously to investigate their functional role. The AA1E3BER4 protein was located downstream of Hog1 in the HOG branch pathway and was identified that was regulated by AcHog1. Furthermore, yeast two-hybrid analysis showed that AA1E3BER4 interacted with AcHog1. In addition, we knocked out and complemented the Acsko1 gene encoding the AA1E3BER4 protein. We found that the number of sexual and asexual spores were downregulated by 3.81- and 4.57-fold, respectively, in the ΔAcsko1 strain. The sensitivity of the ΔAcsko1 strain to sorbitol and sucrose, as regulators of osmotic stress, increased, and the sensitivity to high sucrose was higher than that of sorbitol. Acsko1 also regulated the response of A. cristatus to oxidative stress, Congo red, and SDS (sodium dodecyl sulfate). In addition, the deletion of Acsko1 significantly increased the pigment of the ΔAcsko1 strain. This is the first study to report the role of the sko1 gene in oxidative stress, stress-induced damage to the cell wall, and pigment in Aspergillus cristatus.

It is crucial to implement appropriate measures to prevent the spread of plant pathogens that lead to the decay of fruits and vegetables. From this perspective, we evaluated the biocontrol potential of five Bacillus-plant growth promoting rhizobacteria (PGPR) strains against twenty-one pectinolytic phytopathogens causing soft rot in fruits and vegetables. These phytopathogens had been previously studied. Three in vitro methods were utilized to accomplish this objective: competition, extraction of bioactive substances, and direct confrontation. The inhibitory effect of the direct confrontation method resulted in a slower growth of 11 microbial plant pathogens. In addition, it was noted that 11 strains of plant pathogens generated inhibitory constituents, while 15 plant pathogens produced inducible inhibitory substances. Furthermore, volatile inhibitory compounds were detected in the six tested strains. Overall, strains of PGPR-Bacillus demonstrated strong antifungal and antibacterial properties against phytopathogens. These PGPR can be regarded as potential biocontrol agents for soft microbial rot in fruits and vegetables as well as producers of substances that effectively suppress plant diseases.

Cover illustration:

Transmission electron microscopy image of streptophage S3.

(Photo: Thomas Krauße, Institute of Microbiology, Friedrich-Schiller University, Jena, Germany)

During the cultivation of button mushrooms, the green mold epidemic, which causes a decrease in productivity, is a very important problem. The environmental harm of chemicals used in the control of such epidemics and the demand of consumers for organic products without chemicals have brought environmentally friendly biological control to the fore. Biological control can be achieved by the use of antagonistic microorganisms and their metabolites. In this study, the effectiveness of Bacillus spp. and Pseudomonas spp. for the biological control of the aggressive biotypes of the green mold disease agent Trichoderma aggressivum strains was examined in vitro. For this purpose, the antifungal effects of Bacillus spp. and Pseudomonas spp. against T. aggressivum strains were examined by in vitro dual culture test. Afterward, the antifungal activity of Bacillus spp. metabolites was assessed further using the agar well diffusion method. Then, it was determined whether the bacterial strains showing antifungal activity showed antagonistic activity against A. bisporus. Although none of the Pseudomonas spp. showed antifungal activity against T. aggressivum strains, most of the Bacillus spp. were found to have high activity. It has been concluded that Bacillus sp. Ö-4-82 may be potential biological control agent for button mushroom cultivation.

Monacolin K is a valuable secondary metabolite produced after a period of fermentation by Monascus purpureus; however, our current understanding of the regulatory mechanisms of its synthesis remains incomplete. This study conducted functional analysis on the key transcription factor, comp54181_c0, that is involved in the synthesis of monacolin K in Monascus. Mutant strains with either knockout or overexpression of comp54181_c0 were constructed using CRISPR/Cas9. A comparison between the knockout and overexpression strains revealed changes in fungal morphology and growth, with a significant increase in the production of Monascus pigments and monacolin K when comp54181_c0 was absent. Real-time fluorescence quantitative PCR analysis revealed that comp54181_c0 significantly influenced the transcription of key genes related to monacolin K biosynthesis in Monascus. In conclusion, our study elucidates the crucial role of comp54181_c0 in Monascus, enriches our understanding of fungal secondary metabolite development and regulation, and provides a foundation for the development and regulation of Monascus and monacolin K production.

The globally vital oil palm, a major oil producer, confronts productivity challenges due to Ganoderma boninense (Gb), causing output decline. Chemical control efforts have proven ineffective, prompting exploration of microbial-based biocontrol. While single fungal biocontrol research exists, the impact of employing multiple biocontrols concurrently to combat Ganoderma and enhance oil palm growth remains uncharted. This study examined four soil-derived fungal isolates for their ability to antagonize Gb PER71 in vitro. Molecular identification categorized them as Talaromyces spp. and Penicillium sp. Moreover, all isolates were revealed to have at least three plant growth-promoting (PGP) traits and were shown to have phosphoric hydrolase, ester hydrolase, peptide hydrolase, and glycosidase activities which are essential for plant growth. Furthermore, the synergistic evaluation of fungal isolates was tested against Gb PER71. One out of six combinations of fungal isolates showed a synergistic effect in vitro, and two showed a synergistic effect in planta. The application of single and combined fungal isolates tested in planta also suppressed Gb PER71 and enhanced oil palm growth compared to control groups. The findings indicate the promising potential of these isolates as biocontrol agents (BCAs) and bioformulations against Gb in oil palm cultivation.