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Background  Autophagy is used for degradation of cellular components and nutrient recycling. Atg8 is one of the core proteins in autophagy and used as a marker for autophagic detection. However, the autophagy of filamentous fungi is poorly understood compared with that of  Saccharomyces cerevisiae . Our previous study revealed that disruption of the autophagy related gene  Acatg1  significantly enhanced cephalosporin C yield through reducing degradation of cephalosporin biosynthetic proteins in  Acremonium chrysogenum , suggesting that modulation of autophagic process is one promising way to increase antibiotic production in  A. chrysogenum .    Results  In this study, a  S. cerevisiae ATG8  homologue gene  Acatg8  was identified from  A. chrysogenum .  Acatg8  could complement the  ATG8  mutation in  S. cerevisiae , indicating that  Acatg8  is a functional homologue of  ATG8 . Microscope observation demonstrated the fluorescently labeled AcAtg8 was localized in the cytoplasm and autophagosome of  A. chrysogenum , and the expression of  Acatg8  was induced by nutrient starvation. Gene disruption and genetic complementation revealed that  Acatg8  is essential for autophagosome formation. Disruption of  Acatg8  significantly reduced fungal conidiation and delayed conidial germination. Localization of GFP-AcAtg8 implied that autophagy is involved in the early phase of conidial germination. Similar to  Acatg1 , disruption of  Acatg8  remarkably enhanced cephalosporin C yield. The cephalosporin C biosynthetic enzymes (isopenicillin N synthase PcbC and isopenicillin N epimerase CefD2) and peroxisomes were accumulated in the  Acatg8  disruption mutant (∆Acatg8), which might be the main reasons for the enhancement of cephalosporin C production. However, the biomass of ΔAcatg8 decreased drastically at the late stage of fermentation, suggesting that autophagy is critical for  A. chrysogenum  cell survival under nutrition deprived condition. Disruption of  Acatg8  also resulted in accumulation of mitochondria, which might produce more reactive oxygen species (ROS) which promotes fungal death. However, the premature death is unfavorable for cephalosporin C production. To solve this problem, a plasmid containing  Acatg8  under control of the xylose/xylan-inducible promoter was introduced into ∆Acatg8. Conidiation and growth of the recombinant strain restored to the wild-type level in the medium supplemented with xylose, while the cephalosporin C production maintained at a high level even prolonged fermentation.    Conclusions  Our results demonstrated inducible expression of  Acatg8  and disruption of  Acatg8  remarkably increased cephalosporin C production. This study provides a promising approach for yield improvement of cephalosporin C in  A. chrysogenum.Electronic supplementary material  The online version of this article (10.1186/s12934-018-1021-9) contains supplementary material, which is available to authorized users.

Enhancing the production of cephalosporin C through modulating the autophagic process of Acremonium chrysogenum