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The phenomenon of strain degeneration in biotechnologically relevant fungi

Summary

Fungi used in industries to produce antibiotics, enzymes, and other useful products sometimes mysteriously lose their ability to produce these substances effectively. This review explains why this happens through various mechanisms including genetic changes, chemical modifications of genes, and stress responses. The authors provide practical strategies to prevent this loss of productivity, such as careful strain selection, proper storage methods, and tailored bioprocess design to maintain stable production.

Background

Fungi are widely exploited in biotechnology for large-scale production of diverse substances including antibiotics, enzymes, and organic acids. However, spontaneous loss or decline of production capacity, known as fungal strain degeneration, occurs in commonly used genera like Aspergillus, Trichoderma, and Penicillium, resulting in significant economic losses.

Objective

This mini-review addresses fungal strain degeneration by describing examples of productivity losses in biotechnical processes using Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, and Penicillium chrysogenum. The review discusses potential underlying mechanisms including genetic and epigenetic factors, and explores circumvention and prevention strategies.

Results

Multiple mechanisms underlying fungal degeneration were identified including genetic mutations with selective advantages for non-producing cells, epigenetic changes affecting chromatin structure and gene expression, and stress responses including oxidative stress and unfolded protein response. Different fungal species showed distinct patterns of degeneration with productivity losses ranging from 30-100%.

Conclusion

Fungal strain degeneration is a complex phenomenon involving multiple genetic, epigenetic, and stress-related mechanisms that remain poorly understood. The review emphasizes that tailored solutions require understanding the specific underlying mechanisms for each strain and process, and recommends strain selection based on stability characteristics and bioprocess design strategies.
  • Published in:Applied Microbiology and Biotechnology,
  • Study Type:Review,
  • Source: PMID: 37341752, DOI: 10.1007/s00253-023-12615-z
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