Transcriptomic profiling of pullulan-related genes in low-yielding Aureobasidium pullulans mutants

Pullulan is a biopolysaccharide with broad applications in the food industry as a functional additive. Thus, elucidating the relationship between the molecular weights of pullulan and its intricate synthetic pathway is imperative. In this study, a pullulan yield analysis was conducted on two negative mutants, dMu0601 and dMu1302, from Aureobasidium pullulans RM1603 derived by ARTP mutagenesis, and the pullulan yields decreased by 13.9% and 11.7%, respectively. However, the weight-average molecular weight (Mw) of pullulan was markedly increased in dMu0601 (864.8 kDa), dMu1302 (825.2 kDa), and positive mutants Mu0816 (682.4 kDa), Mu1519 (525.3 kDa), compared with RM1603 (180.9 kDa). A total of 1059 and 1575 differentially expressed genes (DEGs) were identified in dMu0601 and dMu1302, respectively, based on transcriptome analysis. Multiple DEGs associated with carbohydrate metabolism, glycosylation, and energy/redox pathways may be related to the altered pullulan phenotype. Transcriptomic analyses of negative mutants have rarely been reported in previous studies. This study establishes a theoretical foundation for further clarification of pullulan synthesis.