Characterization of linoleate dioxygenases in basidiomycetes and the functional role of CcLdo1 in regulating fruiting body development in Coprinopsis cinerea.

Coprinopsis cinerea, a model fungus, is utilized for investigating the developmental mechanisms of basidiomycetes. The development of basidiomycetes is a highly organized process that requires coordination among genetic, environmental, and physiological factors. Oxylipins, a class of widely distributed signaling molecules, play crucial roles in fungal biology. Among oxylipins, the sexual pheromone-inducing factors (psi factors) have been identified as key regulators of the balance between asexual and sexual spore development in Ascomycetes. Linoleate dioxygenases are enzymes involved in the biosynthesis of psi factors, yet their specific physiological functions in basidiomycete development remain unclear. In this study, linoleate dioxygenases in basidiomycetes were identified and characterized. Phylogenetic analysis revealed that linoleate dioxygenases from Basidiomycota formed a distinct clade, with linoleate dioxygenases from Agaricomycetes segregating into three groups and those from Ustilaginomycetes forming a separate group. Both basidiomycete and ascomycete linoleate dioxygenases shared two characteristic domains: the N-terminal of linoleate dioxygenase domain and the C-terminal of cytochrome P450 domain. While the linoleate dioxygenase domains exhibited similarity between basidiomycetes and ascomycetes, the cytochrome P450 domains displayed high diversity in key sites. Furthermore, the gene encoding the linoleate dioxygenase Ccldo1 in C. cinerea was knocked out, resulting in a significant increase in fruiting body formation without affecting asexual conidia production. This observation suggests that secondary metabolites synthesized by CcLdo1 negatively regulate the sexual reproduction process in C. cinerea while not influencing the asexual reproductive process. This study represents the first identification of a gene involved in secondary metabolite synthesis that regulates basidiocarp development in a basidiomycete.

Influence of spore concentration on microorganism morphology and on glucoamylase production in submerged cultures of Aspergillus awamori

The influence of the spore concentration in the inoculum preparation on microorganism morphology and glucoamylase synthesis by submerged cultures of Aspergillus awamori was investigated. A series of fermenter runs were perfomed, using an initial total reducing sugar concentration of 40 g/L. The inocula were prepared in a rotatory shaker, at 35§C 200 rev/min for 24 hours, varying spore concentration in the flasks from 9.5 x 10(3) to 1.8 x 10 (7) spores/mL. The inocula prepared with a spore concentration between 9.5 x 10(3) spores/mL and 5.0 x 10(6) spores/mL were composed by a cell suspension mainly in the pellet form, which led to a filamentous growth in the fermenter. Glucoamylase production was not affected by this range of spore concentration, reaching values between 2,100 U/L and 2,300 U/L. However, a higher spore concentration in the inoculum preparation (1.8 x 10(7) spores/mL) led to a inoculum formed by a cell suspension in the filamentous form containing many spore agglomerates (non-germinated spores). The kind of inoculum led to a growth predominantly in the pellet form in fermenter, which reduced the glucoamylase production in 30 (per cent).