Space exposure enhanced pectin-degrading enzymes expression and activity in Aspergillus costaricaensis

Aspergillus is a well-studied fungal genus that is widely used in the processing of plant biomass in industries. This study investigated the effects of space exposure on the ability of Aspergillus costaricaensis , a filamentous fungus isolated from rotten orange peel, to degrade pectin. The fungus was carried into space by the Long March 5B carrier rocket and exposed to cosmic radiation for 79 hours. After the flight, the strains were screened using pectin as the sole carbon source for directed screening and pectinase activity evaluation. The space-exposed strains showed increased biomass accumulation ability and pectin-degrading activity compared to the ground control strain. Comparative transcriptome analysis revealed that several CAZymes genes were significantly upregulated in the space-exposed strains, especially those related to pectin degradation. Among the 44 pectinases identified from the annotated genome, 42 were up-regulated. The identified activities of these pectinases can break down the four basic structures of pectin, and work together to break down pectin substrates. In addition, the expression of some genes involved in metabolism, sugar transport, and stress response were altered. These results suggest that the space environment can be used as a mutagenesis breeding technique to create highly efficient biomass-degrading microbial strains, with potential applications in biotechnology and bioengineering.