Fungi are the major species causing microbial deterioration that reduces the commercial value of wood, such as wood decay and surface contamination, so it is important to accumulate knowledge on the physiology of fungi in order to develop countermeasures against these problems. Most physiological studies of fungi that have been reported have concerned the metabolism of carbohydrates as a source of energy and nitrogen as a relatively abundant biocomponent element. On the other hand, for micronutrient elements such as sulfur, despite their physiological importance, there is limited knowledge on their acquisition sources and metabolic pathways. We have previously found that the soil Ascomycota and wood-rotting Basidiomycota have the ability to degrade carbonyl sulfide (COS), the most abundant gaseous sulfur compound in the atmosphere, and have identified a COS hydrolase (COSase, COS + H2O → CO2 + H2S) that hydrolyzes COS from the filamentous Ascomycota Trichoderma harzianum strain THIF08. However, the physiological role of COS degradation in those fungi is not clear. In this study, to gain further insight into COS degradation by fungi, we analyzed sulfur metabolites in T. harzianum strain THIF08 using gaseous COS or sulfate as the sulfur source. In addition, to investigate the evolution of COSase, which is suggested to play an important role in fungal COS degradation, we conducted a homology search of COSase genes using the fungal genome database and its phylogenetic analysis. As a result, different patterns of sulfur metabolites were observed between COS and sulfate when they were used as the sulfur source, respectively. It was also found that COSase homology was widely patchy in fungi.

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