Superoxide dismutases (SODs) play crucial roles in protecting cells against oxidative stress by catalyzing the dismutation of superoxide radicals. In Aspergillus nidulans, five putative SOD genes have been predicted in the genome; however, their comparative expression profiles and physiological functions remain largely uncharacterized. In this study, we analyzed the expression levels of all five SOD genes at different growth stages and examined the oxidative stress sensitivity of corresponding gene-disrupted strains. We found that sodA exhibited high and constitutive expression across all growth stages, while sodB was predominantly expressed in conidia (asexual spores). Disruption mutants of sodA and sodB showed increased sensitivity to oxidative agents, confirming their functional importance. Subcellular fractionation and SOD activity assays revealed that SodA was localized in the cytoplasm, whereas SodB was primarily localized in mitochondria. These results highlight the growth stage-specific expression and distinct cellular roles of SodA and SodB in A. nidulans, providing novel insights into the oxidative stress defense system in filamentous fungi.

Superoxide dismutases (SODs) play crucial roles in cellular oxidative stress defense. In Aspergillus nidulans, SodB is a mitochondria-localized SOD whose physiological function remains poorly understood. Here, we show that a ΔsodB mutant displays impaired growth on non-fermentable carbon sources including acetate, ethanol, threonine, and Tween 20/80, suggesting compromised mitochondrial function. Oxygen consumption assays using an extracellular oxygen consumption reagent revealed a ~50% reduction in respiratory activity in the ΔsodB strain compared to the wild type. When mitochondrial respiration was inhibited by Antimycin A or salicylhydroxamic acid, giant colony growth was equally suppressed across wild-type, ΔsodA, ΔsodB, and complemented strains. However, conidial production was significantly reduced in ΔsodB under Antimycin treatment, and morphological abnormalities in conidiophore heads were observed under this condition. These results indicate that SodB is not only involved in mitochondrial respiration but also required for maintaining normal sporulation under mitochondrial stress conditions. This study provides new insights into the role of mitochondrial ROS defense systems in filamentous fungal development.

At the 2025 Osaka/Kansai Expo, a bacterial-bioluminescence-based lighting system, called BIOLIGHT, was exhibited. It consists of 80 liters of liquid culture medium and produces enough brightness to illuminate a room. In this study, to make clear the relationship between the liquid culture thickness and the brightness using BIOLIGHT, the world's largest liquid culture aquarium of bioluminescent bacteria, we investigated the brightness of the bacterial liquid culture in relation to optical density (OD). The theoretical brightness of BIOLIGHT was calculated using the transmittance of the liquid culture at 475 nm (the peak luminescence wavelength) derived from the measured OD and was then compared with the brightness actually measured. The calculated (theoretical) brightness was lower than the measured one, suggesting that the light output of BIOLIGHT is influenced not only by cell-induced light shielding but also by another factor, presumably forward scattering. Additionally, depth-dependent brightness measurements showed that brightness became saturated at a liquid culture thickness greater than 7 cm. These findings will contribute to the design of future lighting solutions using bacterial bioluminescence.

Methionine gamma-lyase enzyme was isolated and purified from Mucor irregularis PQ344458 fungal isolates, that obtained from plant root, the isolates were identified through observation of their colony morphological features, implementation of PCR and DNA sequencing via sanger-chain termination approach, then data of DNA sequence alignment, phylogenetic tree, percent identity was generated. Through implementation of several stages that involved using of ion-exchange chromatography, gel-filtration chromatography, ammonium sulphate, enzyme isolation and purification stages were accomplished. The enzyme extract then, was analyzed for its protein content, specific activity and Impact of pH, temperature, inhibitors and activators on its kinetics. Additionally, MTT and DPPH radical scavenging assays were carried-out to reveal information about anti-cancer and anti-oxidant activities of methionine gamma-lyase enzyme. MTT assay results of %viable cells were 15% for HeLa cells and 6.6% for U937 cells at maximum concentration of the enzyme extract. Moreover, DPPH scavenging activity results were 82% at maximum concentration.

In the biosynthesis of peptidoglycan (PG), murE protein (MurE) adds a diamino acid at position 3 of the peptide chain of peptidoglycan. The diamino acid that is added by MurE and makes cross-linkage with adjacent peptide chain differs depending on the bacterial species: Gram-negative bacteria add meso-diaminopimelic acid (DAP), while most Gram-positive bacteria add L-lysine (Lys). In this study, the murE gene of Levilactobacillus brevis that transfers Lys in PG synthesis was cloned into Escherichia coli that has DAP-type PG. The transformant cells harboring L. brevis murE showed reduction of colony forming units during cultivation, and were elongated or burst when murE was expressed. Amino acid analysis of solubilized PG revealed that the Lys/DAP ratio increased in the PG of the transformants. Interestingly, aspartic acid that is responsible for the formation of cross-linkages between Lys and other peptide chain in the PG of L. brevis also increased, suggesting that Lys-type PG with Asp cross-linkage was partially formed by the cloning of murE gene.

The extracellular export of target chemicals is essential for achieving the target productivity of microbial cell factories (MCFs). We demonstrated that MscCG, a mechanosensitive channel responsible for glutamate export in glutamate-producing MCF of Corynebaterium glutamicum, can export various intracellular low-molecular-weight chemicals outside the cell. The mechanosensitive channels exporter improved L-Lys productivity and conferred substantial 5′-IMP fermentative production ability to the Escherichia coli MCF, which lacks inherent 5′-IMP exporters, indicating that mechanosensitive channels, which are low selective, functioned effectively as MCF exporters. We also demonstrated the effectiveness of a gain-of-function (GOF) mutation of mechanosensitive channels as MCF exporters; however, the essential mechanism underlying this GOF mutation remains unknown. Therefore, we performed molecular dynamics simulations to identify this mechanism at the atomic level. Consequently, we partially elucidated the underlying mechanism of G46D-induced GOF in MscL, which was effective as a 5′-IMP exporter. Specifically, the kink at A38 in the inner transmembrane helix of MscL forming its pore can affect GOF behavior. Based on these results, we conclude that mechanosensitive channels have potential as innovative and versatile exporters of MCFs, capable of enhancing the production efficiency of target chemicals and enabling their production in the absence of natural exporters.

Actinoplanes missouriensis grows by forming branched substrate mycelia and produces terminal sporangia. Each sporangium contains a few hundred spores, which swim as zoospores after being released from sporangia. Previously, we disrupted 22 putative acyltransferase genes and examined their involvement in morphological differentiation. Here, we described the characterization of one of them, a putative 1-acyl-2-hydroxy-sn-glycerol-3-phosphate acyltransferase (AGPAT) encoded by plsC (AMIS_11360). The plsC null (∆plsC) mutant exhibited a conditional growth defect in a nutrient-poor medium. No differences were observed between the wild-type and ∆plsC strains in sporangium formation, spore release, or zoospore motility. We confirmed the AGPAT activity of PlsC; the recombinant polyhistidine-tagged PlsC protein transferred the acyl group from palmitoyl-coenzyme A to 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphate, resulting in the production of 1,2-dipalmitoyl-sn-glycero-3-phosphate.

We investigated the effect of a starter culture on the fungal communities of commercial karebushi. Aspergillus pseudoglaucus was initially identified as the starter fungus. In karebushi samples from two manufacturers relying on naturally occurring molds, Aspergillus chevalieri was the dominant species, accompanied by Aspergillus montevidensis and Aspergillus sydowii, while A. pseudoglaucus was not detected. Among samples from six manufacturers that used the starter culture, A. pseudoglaucus was dominant in only three; in the remaining three, A. chevalieri predominated despite the starter being used. These results suggest that indigenous fungi, particularly A. chevalieri, present in the processing environment can outcompete the starter culture, influence the fungal community, and potentially contribute to the qualitative diversity of karebushi.