Discovery of a polyvinyl alcohol-degrading strain of the ascomycete Fusarium oxysporum and optimizing of its degradation performance of PVA

Abstract

Massive accumulation of plastics into environment has caused enormous pressure on the ecosystem. Efficient and environmentally friendly plastics degradation technologies have evolved into a global ecological challenge. Microbial degradation, as an eco-friendly plastic treatment technology, is confronted with a problem of low efficiency in its current application. Hence, it is crucial to discovery plastic biodegradable microorganisms and find the optimal conditions for their action. The aim of our study is to isolate plastic-biodegrading fungi and explore optimum conditions for their action. A strain isolate of Fusarium oxysporum was obtained from a degraded plastic handle through screening, separation, and purification and designated PDBF01 (CGMCC No.40272). In a screening assay of plastic polymers, PDBF01 only exhibited the degradability to polyvinyl alcohol (PVA), with no activity toward polyvinyl chloride, polypropylene, or polylactic acid. PVA degradation efficiency of PDBF01 was significantly affected by inoculum concentration, temperature, and degradation time. PDBF01 produced significant degradation of PVA under 28°C and 25% inoculum concentration. Moreover, the highest degradation rate reached 51.26% after 21 days. PVA degradation rate of PDBF01 was further increased to 58.83% by the addition of electrolytes (K+, Mg2+, Fe2+, and Ca2+). Our results suggested PDBF01 can be used as a potential and efficient PVA-degrading strain in practical applications.