The phenomenon of strain degeneration in biotechnologically relevant fungi

Abstract

Fungi are widely exploited for large-scale production in the biotechnological industry to produce a diverse range of substances due to their versatility and relative ease of growing on various substrates. The occurrence of a phenomenon—the so-called fungal strain degeneration—leads to the spontaneous loss or decline of production capacity and results in an economic loss on a tremendous scale. Some of the most commonly applied genera of fungi in the biotechnical industry, such as Aspergillus, Trichoderma, and Penicillium, are threatened by this phenomenon. Although fungal degeneration has been known for almost a century, the phenomenon and its underlying mechanisms still need to be understood. The proposed mechanisms causing fungi to degenerate can be of genetic or epigenetic origin. Other factors, such as culture conditions, stress, or aging, were also reported to have an influence. This mini-review addresses the topic of fungal degeneration by describing examples of productivity losses in biotechnical processes using Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, and Penicillium chrysogenum. Further, potential reasons, circumvention, and prevention methods are discussed. This is the first mini-review which provides a comprehensive overview on this phenomenon in biotechnologically used fungi, and it also includes a collection of strategies that can be useful to minimize economic losses which can arise from strain degeneration. Key points • Spontaneous loss of productivity is evident in many fungi used in biotechnology. • The properties and mechanisms underlying this phenomenon are very versatile. • Only studying these underlying mechanisms enables the design of a tailored solution.

Aspergillus oryzae as a Cell Factory: Research and Applications in Industrial Production

“…Metabolic engineering strategies and synthetic biology tools have the potential to significantly enhance the performance of A. oryzae, encompassing synthesis capacity, growth performance, and stress resilience [123,124]. Despite the sequencing of the genomic information of A. oryzae, the metabolic pathways of numerous secondary metabolites remain elusive, presenting a major challenge in related research.…”

High-throughput screening carbon and nitrogen sources to promote growth and sporulation in Rhizopus arrhizus

“…Fungal degeneration entails the spontaneous loss or decline in production capacity, resulting in significant economic losses. This phenomenon poses a threat to some of the widely utilized fungal genera in the biotechnical industry, such as Aspergillus , Penicillium , and Trichoderma (Adrio and Demain 2003 ; Douma et al 2011 ; Song et al 2022 ; Danner et al 2023 ). Similar with these fungi, as the number of passages increases and artificial domestication of fermentation environment is prolonged, certain R. arrhizus strains may progressively undergo degradation, which is primarily characterized by a sluggish expansion of mycelia, a reduction in sporangiospore quantities, and even a complete absence of sporangiospore production.…”

The Conservation and Study of Macromycetes in the Komarov Botanical Institute Basidiomycetes Culture Collection—Their Taxonomical Diversity and Biotechnological Prospects

“…Unfortunately, when this method is applied for long-term strain preservation, it sooner or later causes strain deterioration [48]. This well-known problem is encountered not only when fungal strains are maintained in culture collections but also when they are used as long-term producers in biotechnology [49]. The disk method in screw-cap cryovials under distilled water at 4-6 • C was suggested by Burdsall and Dorworth in 1994 for wood-decaying fungi.…”