ABSTRACT The Natural rubber (NR) biodegradation by three microorganisms has been evaluated: a yeast (Rhodotorula mucilaginosa) and a bacterium (Pseudomonas sp.), isolated in a liquid culture from soil, and a filamentous fungus (Alternaria alternata), isolated on a solid culture from an NR surface, were tested. The biodegradation was conducted for four months in liquid culture, at 30°C, in agitated and stationary conditions, using a Mineral Salt Medium with NR as the only carbon source. The growth behaviour of the yeast and the bacterium was evaluated by means of optical density measurements (OD650). At the end of the incubation, the dry weight biomass of the microorganisms was measured. R. mucilaginosa showed a higher biomass production in the agitated culture, while a more efficient production was observed in static conditions for the Pseudomonas and A. alternata strains. The highest enzymatic activity of Lignin peroxidase (LiP) and Manganese-dependent peroxidase (MnP) was obtained in static conditions for A. alternata. The laccase production was probed by guaiacol oxidative polymerization on agar plates. The microorganism biodegradation capability was assessed through a combination of SEM analysis, FTIR-ATR spectroscopy, and Size Exclusion Chromatography techniques. An extended mycelium-substrate interphase and a decrease in the NR molecular weight were observed.

中文翻译：

---

从土壤和橡胶表面分离的微生物对未硫化天然橡胶的生物降解：初步研究

摘要 已经评估了三种微生物对天然橡胶 (NR) 的生物降解作用：一种酵母（Rhodotorula mucilaginosa）和一种细菌（Pseudomonas sp.），从土壤的液体培养物中分离出来，以及一种丝状真菌（Alternaria alternata），分离在一种对来自 NR 表面的固体培养物进行了测试。在 30°C、搅拌和静止条件下，使用以 NR 作为唯一碳源的矿物盐培养基，在液体培养中进行了四个月的生物降解。酵母和细菌的生长行为通过光密度测量 (OD650) 进行评估。在温育结束时，测量微生物的干重生物量。R. mucilaginosa 在搅拌培养中显示出更高的生物量产量，而在静态条件下观察到假单胞菌和交替链球菌菌株的生产效率更高。木素过氧化物酶 (LiP) 和锰依赖性过氧化物酶 (MnP) 的最高酶活性是在 A. alternata 的静态条件下获得的。通过在琼脂平板上的愈创木酚氧化聚合来探测漆酶的产生。通过 SEM 分析、FTIR-ATR 光谱和尺寸排阻色谱技术的组合评估微生物的生物降解能力。观察到延长的菌丝体-基质界面和 NR 分子量的降低。通过在琼脂平板上的愈创木酚氧化聚合来探测漆酶的产生。通过 SEM 分析、FTIR-ATR 光谱和尺寸排阻色谱技术的组合评估微生物的生物降解能力。观察到延长的菌丝体-基质界面和 NR 分子量的降低。通过在琼脂平板上的愈创木酚氧化聚合来探测漆酶的产生。通过 SEM 分析、FTIR-ATR 光谱和尺寸排阻色谱技术的组合评估微生物的生物降解能力。观察到延长的菌丝体-基质界面和 NR 分子量的降低。