Study on degradation pattern and properties about in situ degradation mechanism of biodegradable polymer

研究了土壤中真菌对3-羟基丁酸-3-羟基戊酸共聚物（PHBV）膜微生物降解的贡献。在PHBV膜的凹陷表面上观察到的各种痕迹、空腔和凹槽表明，降解是在膜表面上定殖的微生物聚生体（包括真菌、细菌和放线菌）的协同效应。降解过程中PHBV薄膜周围土壤中的微生物群落的演替表明，真菌种群明显增加，导致其占主导地位。从降解PHBV膜的土壤中分离的微生物菌株的降解能力的比较表明，真菌对土壤中PHBV的降解贡献最大，在那里，它们沿着膜表面非常快速地生长，具有高降解能力，然后以三维方式扩展它们的菌丝。根据真菌菌丝的表面生长速率和真菌解聚酶的降解能力，对土壤中3-羟基丁酸-co-3-羟基戊酸（PHBV）膜进行了数学描述。真菌的表面生长速率是从等效对称树模型的概念推导出来的，并表示为两个不同的生长阶段，即，指数阶段和减速阶段。所建立的生长和降解模型能较好地代表真菌降解PHBV的实验数据。真菌降解PHBV膜的同时，土壤团聚体的形成为真菌生长和PHBV降解提供了有利条件。PHBV膜在土壤中的降解速率取决于PHBV膜表面定殖真菌的数量及其降解能力

The contribution of fungi to the microbial degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)films in soil was studied. Various traces, cavities and grooves, observed on the dented surface of PHBV films demonstrated that the degradation was a concerted effect of a microbial consortium colonizing on the film surface including fungi, becteria and actinomycetes. The succession of microbial consortia in the soil around the PHBV films during the degradation showed a distinctive increase in the fungal population resulting in its dominance. Comparison of the degradation ability of microbial strains isolated from the soil, where PHBV films were degraded, revealed that fungi showed the highest contribution to the PHBV degradation in soil, where they grew very rapidly along the film surface with their high degradation ability and then expanded their hyphae in a three-dimensional manner.Fungal degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)film in soil was described mathematically in terms of the surface growth rate of fungal hyphae and the degradation ability of fungal depolymerase. the surface growth rate of fungi was derived from the notion of equivalent symmetric tree model and was expressed for the two different growth phases, i.e., exponential phase and deceleration phase. The proposed growth and degradation models represented well the experimental data obtained from fungal PHBV degradation in soil. Fungi degrade PHBV film with the formation of soil aggregate that gives the advantageous condition for fungal growth and PHBV degradation. Fungal degradation rate of PHBV film in soil depends on the population of colonized fungal biomass on PHBV film surface and their degradation ability