School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
GE Digital, 19015 North Creek Parkway, Bothell, WA, 98011, USA.
Biodegradation. 2020 Dec;31(4-6):265-273. doi: 10.1007/s10532-020-09908-9. Epub 2020 Sep 19.
Chlortetracycline (CTC) has been widely used in veterinary medicine in recent years, which has resulted in severe environmental issues due to its low degradation rate and high risk to induce antibiotic resistance bacteria and genes. In previous studies, CTC could be efficiently degraded by Trichoderma harzianum LJ245. Nevertheless, the strain itself suffers from relatively poor adaptability due to the limited number of spores produced. In this paper, ultraviolet (UV) mutagenesis was conducted on LJ245, and various mutants with high sporulation rate were generated to expand the environmental adaptability and enhance CTC degradation. An OmniLog-based method, where 95 types of carbon sources were applied, was first proposed to acquire the carbon metabolic profile of the strains. Several controlled experiments were performed to evaluate the impact of co-substrate metabolism on strain growth, CTC biodegradation, and metabolites biotoxicity removal. The result shows that produced mutants could significantly broaden the carbon metabolic profile and expand the environmental adaptability compared to the original LJ245, where the mutants obtained remarkable increase in total number of usable carbon sources. Meanwhile, as the sole carbon source, CTC could not be fully degraded by the strains. However, the use of co-metabolism could considerably enhance CTC degradation and completely remove CTC degradation products biotoxicity by all strains. Specifically, amino acids and carboxylic acids had the best performance on both strain growth and CTC degradation among all carbon source categories. The results can be applied to the biodegradation treatment of CTC in solid residue, waste water and other environments.
近年来，金霉素（CTC）在兽医医学中得到了广泛应用，但由于其降解率低，且存在诱导抗生素抗性细菌和基因的高风险，导致了严重的环境问题。在之前的研究中，CTC 可被哈茨木霉 LJ245 高效降解。然而，由于产生的孢子数量有限，该菌株本身的适应性较差。本研究对 LJ245 进行了紫外线（UV）诱变，生成了各种具有高产孢率的突变体，以扩大环境适应性并增强 CTC 降解能力。首先提出了一种基于 OmniLog 的方法，该方法应用了 95 种碳源，以获得菌株的碳代谢谱。进行了几项对照实验，以评估共代谢物对菌株生长、CTC 生物降解和代谢物生物毒性去除的影响。结果表明，与原始 LJ245 相比，产生的突变体能显著拓宽碳代谢谱并扩大环境适应性，突变体可利用的碳源总数显著增加。同时，作为唯一的碳源，CTC 不能被菌株完全降解。然而，共代谢作用的使用可以显著增强 CTC 降解，并通过所有菌株完全去除 CTC 降解产物的生物毒性。具体来说，在所有碳源类别中，氨基酸和羧酸对菌株生长和 CTC 降解的效果最好。该结果可应用于 CTC 在固体残渣、废水和其他环境中的生物降解处理。
