Andler R, D'Afonseca V, Pino J, Valdés C, Salazar-Viedma M
Escuela de Ingeniería en Biotecnología, Centro de Biotecnología de los Recursos Naturales (Cenbio), Universidad Católica del Maule, Talca, Chile.
Centro de Investigación de Estudios Avanzados del Maule, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile.
Front Bioeng Biotechnol. 2021 Oct 18;9:761510. doi: 10.3389/fbioe.2021.761510. eCollection 2021.
Millions of tonnes of tyre waste are discarded annually and are considered one of the most difficult solid wastes to recycle. A sustainable alternative for the treatment of vulcanised rubber is the use of microorganisms that can biotransform polymers and aromatic compounds and then assimilate and mineralise some of the degradation products. However, vulcanised rubber materials present great resistance to biodegradation due to the presence of highly hydrophobic cross-linked structures that are provided by the additives they contain and the vulcanisation process itself. In this work, the biodegradation capabilities of 10 fungal strains cultivated in PDA and EM solid medium were studied over a period of 4 weeks. The growth of the strains, the mass loss of the vulcanised rubber particles and the surface structure were analysed after the incubation period. With the white rot fungi and , biodegradation percentages of 7.5 and 6.1%, respectively, were achieved. The FTIR and SEM-EDS analyses confirmed a modification of the abundance of functional groups and elements arranged on the rubber surface, such as C, O, S, Si, and Zn, due to the biological treatment employed. The availability of genomic sequences of and in public repositories allowed the analysis of the genetic content, genomic characteristics and specific components of both fungal species, determining some similarities between both species and their relationship with rubber biodegradation. Both fungi presented a higher number of sequences for laccases and manganese peroxidases, two extracellular enzymes responsible for many of the oxidative reactions reported in the literature. This was confirmed by measuring the laccase and peroxidase activity in cultures of and with rubber particles, reaching between 2.8 and 3.3-times higher enzyme activity than in the absence of rubber. The integrative analysis of the results, supported by genetic and bioinformatics tools, allowed a deeper analysis of the biodegradation processes of vulcanised rubber. It is expected that this type of analysis can be used to find more efficient biotechnological solutions in the future.
每年有数百万吨轮胎废弃物被丢弃，它们被认为是最难回收的固体废弃物之一。处理硫化橡胶的一种可持续替代方法是利用能够对聚合物和芳香族化合物进行生物转化，然后将一些降解产物同化和矿化的微生物。然而，由于硫化橡胶材料含有添加剂以及硫化过程本身会形成高度疏水的交联结构，所以它们对生物降解具有很大的抗性。在这项研究中，对在PDA和EM固体培养基中培养4周的10种真菌菌株的生物降解能力进行了研究。在培养期结束后，分析了菌株的生长情况、硫化橡胶颗粒的质量损失以及表面结构。对于白腐真菌 和 ，分别实现了7.5%和6.1%的生物降解率。傅里叶变换红外光谱（FTIR）和扫描电子显微镜-能谱分析（SEM-EDS）证实，由于采用了生物处理，橡胶表面的官能团和元素（如碳、氧、硫、硅和锌）的丰度发生了改变。在公共数据库中可获取 和 的基因组序列，这使得能够分析这两种真菌的遗传内容、基因组特征和特定成分，确定了两种真菌之间的一些相似性以及它们与橡胶生物降解的关系。这两种真菌都有较多数量的漆酶和锰过氧化物酶序列，这两种胞外酶与文献中报道的许多氧化反应有关。通过测量含有橡胶颗粒的 和 培养物中的漆酶和过氧化物酶活性证实了这一点，其酶活性比没有橡胶时高出2.8至3.3倍。在遗传和生物信息学工具的支持下，对结果进行综合分析能够更深入地分析硫化橡胶的生物降解过程。预计这种类型的分析在未来可用于找到更有效的生物技术解决方案。
