Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, 48149, Munster, Germany.
Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia.
Biodegradation. 2021 Apr;32(2):113-125. doi: 10.1007/s10532-020-09920-z. Epub 2021 Mar 6.
The enzymatic degradation of the rubber polymer poly(cis-1,4-isoprene), e.g. by the latex clearing protein Lcp1 of Gordonia polyisoprenivorans VH2 has been demonstrated with latex milk or pure isoprene-rubber particles, recently. Unfortunately, carbon black filled vulcanized rubber (CFVR) making the biggest part of worldwide rubber wastes, contains several harmful additives making microbial and enzymatic rubber degradation challenging. However, this study demonstrates the successful enzymatic cleavage of industrially produced CFVR. The formation of the cleavage products, oligo(cis-1,4-isoprenoids), from incubating CFVR particles with Lcp1 was detected by HPLC-MS. Various organic solvents were tested to remove harmful or inhibiting additives like antioxidants to enhance product formation. The pretreatment of CFVR particles, especially with chloroform or cyclohexane, significantly improved the degradation. It was also demonstrated that reducing the particles size and thus increasing the enzymatically accessible surface area of the particles led to a strong acceleration of the degradation process. Furthermore, ATR-IR analyses showed that Lcp1 led to the functionalization of the rubber particle surface with carbonyl groups by cleaving isoprene chains, still linked to the particle. Both, the oligo(cis-1,4-isoprenoids) as well as the functionalized rubber particles, are potentially important products, which can be reused as fine chemicals or as additives in rubber production. The present study, showing the enzymatic degradation of common CFVR for the first time, takes an important step towards a new way of rubber waste disposal and indicates the economic feasibility of an efficient and environmentally friendly recycling process by using the rubber oxygenase Lcp1.
最近，人们已经证明了橡胶聚合物聚（顺式-1,4-异戊二烯），例如由戈登氏菌属 polyisoprenivorans VH2 的乳胶清除蛋白 Lcp1 进行的酶促降解，可以使用乳胶奶或纯异戊二烯橡胶颗粒进行。不幸的是，含碳黑的硫化橡胶（CFVR）占全球橡胶废物的大部分，其中含有几种有害添加剂，使得微生物和酶促橡胶降解具有挑战性。然而，本研究证明了工业生产的 CFVR 可以成功进行酶促裂解。通过 HPLC-MS 检测到 Lcp1 孵育 CFVR 颗粒时形成的裂解产物低聚物（顺式-1,4-异戊二烯）。测试了各种有机溶剂以去除有害或抑制添加剂，如抗氧化剂，以提高产物形成。CFVR 颗粒的预处理，特别是用氯仿或环己烷，显著提高了降解效率。还证明了减小颗粒尺寸，从而增加颗粒的酶可及表面积，会强烈加速降解过程。此外，ATR-IR 分析表明，Lcp1 通过裂解与颗粒相连的异戊二烯链，导致橡胶颗粒表面的功能化，形成羰基。低聚物（顺式-1,4-异戊二烯）和功能化的橡胶颗粒都是潜在的重要产物，可作为精细化学品或作为橡胶生产中的添加剂再利用。本研究首次证明了常见 CFVR 的酶促降解，朝着一种新的橡胶废物处理方法迈出了重要的一步，并表明通过使用橡胶加氧酶 Lcp1 进行高效、环保的回收过程具有经济可行性。
