Transcriptome analysis of different growth stages of Aspergillus oryzae reveals dynamic changes of distinct classes of genes during growth

BACKGROUND: The gene expression profile and metabolic pathways of Aspergillus oryzae underlying the anatomical and morphological differentiation across different growth stages have not been fully characterized. The rapid development of next-generation sequencing technologies provides advanced knowledge of the genomic organization of A. oryzae. RESULTS: In this study, we characterized the growth and development of A. oryzae at different growth stages, including the adaptive phase, logarithmic phase, and stationary phase. Our results revealed that A. oryzae undergoes physiological and morphological differentiation across the different stages. RNA-seq was employed to analyze the three stages of A. oryzae, which generated more than 27 million high-quality reads per sample. The analysis of differential gene expression showed more genes expressed differentially upon transition from the adaptive phase to the logarithmic and stationary phases, while relatively steady trend was observed during the transition from the logarithmic phase to the stationary phase. GO classification of the differentially expressed genes among different growth stages revealed that most of these genes were enriched for single-organism process, metabolic process, and catalytic activity. These genes were then subjected to a clustering analysis. The results showed that the cluster with the majority of genes with increased expression upon transition from the adaptive phase to the logarithmic phase, and steady expression from the logarithmic phase to the stationary phase was mainly involved in the carbohydrate and amino acid metabolism. CONCLUSION: Our results provide a foundation for identifying developmentally important genes and understanding the biological processes across various growth stages.