Department of Environmental Science, School of Earth Sciences, Central University of Rajasthan, Bandarsindri, Ajmer, Rajasthan, 305817, India.
Institute of Life Sciences, NALCO Nagar Road, NALCO Square, Chandrasekharpur, Bhubaneswar, Odisha, 751023, India.
Arch Microbiol. 2022 Jul 14;204(8):482. doi: 10.1007/s00203-022-03106-2.
Malathion is widely used as an agricultural insecticide, but its toxic nature makes it a serious environmental contaminant. To screen indigenous bacteria for malathion degradation, a strain MAGK3 capable of utilizing malathion as its sole carbon and energy source was isolated from Pennisetum glaucum agricultural soil. Based on morphological and biochemical characteristics and 16S rDNA sequence analysis, strain MAGK3 was identified as Micrococcus aloeverae. The strain was cultured in the presence of malathion under aerobic and energy-restricting conditions, and it grew well in MSM containing malathion (1000 µl/L), showing the highest specific growth rate at 500 µl/L Reverse-phase UHPLC-DAD analysis indicated that 100%, 90.48%, 84.27%, 75.46%, 66.65%, and 31.96% of malathion were degraded within 15 days in liquid culture augmented with 50, 100, 200, 300, 500, and 1000 µl/L concentrations of commercial malathion, respectively. Confirmation of malathion degradation to malathion mono, diacids, and phosphorus moiety was performed by Q-TOF-MS analysis, and a pathway of biodegradation was proposed. The influence of co-substrates was also examined to optimize biodegradation further. Kinetic studies based on different models were conducted, and the results demonstrated good conformity with the first-order model. Malathion degradation process by Micrococcus aloeverae was characterized by R of 0.95, and the initial concentration was reduced by 50% i.e. (DT50) in 8.11 d at an initial concentration of 500 µl/L. This establishes the Micrococcus sp. as a potent candidate for active bioremediation of malathion in liquid cultures as it can withstand high malathion load and can possibly impact the development strategies of bioremediation for its elimination.
马拉硫磷被广泛用作农业杀虫剂，但由于其毒性，它已成为一种严重的环境污染物。为了筛选能够降解马拉硫磷的土著细菌，从狗尾草农田土壤中分离到一株能够利用马拉硫磷作为唯一碳源和能源的 MAGK3 菌株。根据形态学和生物化学特征以及 16S rDNA 序列分析，菌株 MAGK3 被鉴定为微球菌属的一种细菌。在有氧和能量限制条件下，用马拉硫磷培养该菌株，在含有 1000µl/L 马拉硫磷的 MSM 中生长良好，在 500µl/L 时表现出最高的比生长速率。反相高效液相色谱-二极管阵列检测分析表明，在液体培养中添加 50、100、200、300、500 和 1000µl/L 浓度的商业马拉硫磷，15 天内分别有 100%、90.48%、84.27%、75.46%、66.65%和 31.96%的马拉硫磷被降解。通过 Q-TOF-MS 分析证实了马拉硫磷降解为马拉硫磷单酸、二酸和磷部分，并提出了生物降解途径。还研究了共底物的影响，以进一步优化生物降解。根据不同模型进行了动力学研究，结果与一级模型拟合良好。微球菌属对马拉硫磷的降解过程特征为 R 为 0.95，在初始浓度为 500µl/L 时，马拉硫磷的半衰期（DT50）为 8.11 天，即初始浓度降低 50%。这表明，该微球菌属可以作为在液体培养中有效修复马拉硫磷的候选菌，因为它能够耐受高马拉硫磷负荷，并且可能会影响马拉硫磷消除的生物修复发展策略。
