Farhan Muhammad, Ahmad Maqsood, Kanwal Amina, Butt Zahid Ali, Khan Qaiser Farid, Raza Syed Ali, Qayyum Haleema, Wahid Abdul
Sustainable Development Study Center, Government College University, Lahore, Pakistan.
Department of Environmental Sciences, Baluchistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan.
Sci Rep. 2021 May 14;11(1):10320. doi: 10.1038/s41598-021-88264-x.
Extensive pesticides use is negatively disturbing the environment and humans. Pesticide bioremediation with eco-friendly techniques bears prime importance. This study evaluates the bioremediation of chlorpyrifos in soil using indigenous Bacillus cereus Ct3, isolated from cotton growing soils. Strains were identified through ribotyping (16s rRNA) by Macrogen (Macrogen Inc. Geumchen-gu, South Korea). Bacillus cereus Ct3 was resistant up to 125 mg L of chlorpyrifos and successfully degraded 88% of chlorpyfifos in 8 days at pH 8. Bacillus cereus Ct3 tolerated about 30-40 °C of temperature, this is a good sign for in situ bioremediation. Green compost, farmyard manure and rice husk were tested, where ANOVA (P < 0.05) and Plackett-Burman design, results indicated that the farm yard manure has significant impact on degradation. It reduced the lag phase and brought maximum degradation up to 88%. Inoculum size is a statistically significant (P < 0.05) factor and below 10 (CFU g) show lag phase of 4-6 days. Michaelis-Menten model results were as follows; R = 0.9919, V = 18.8, K = 121.4 and V/K = 0.1546. GC-MS study revealed that chlorpyrifos first converted into diethylthiophosphoric acid and 3,5,6-trichloro-2-pyridinol (TCP). Later, TCP ring was broken and it was completely mineralized without any toxic byproduct. Plackett-Burman design was employed to investigate the effect of five factors. The correlation coefficient (R) between experimental and predicted value is 0.94. Central composite design (CBD) was employed with design matrix of thirty one predicted and experimental values of chlorpyrifos degradation, having "lack of fit P value" of "0.00". The regression coefficient obtained was R = 0.93 which indicate that the experimental vales and the predicted values are closely fitted. The most significant factors highlighted in CBD/ANOVA and surface response plots were chlorpyrifor concentration and inoculum size. Bacillus cereus Ct3 effectively degraded chlorpyrifos and can successfully be used for bioremediation of chlorpyrifos contaminated soils.
大量使用农药正在对环境和人类造成负面影响。采用环保技术进行农药生物修复至关重要。本研究评估了从棉花种植土壤中分离出的本地蜡样芽孢杆菌Ct3对土壤中毒死蜱的生物修复效果。菌株由韩国首尔衿川区的Macrogen公司通过核糖体分型（16s rRNA）进行鉴定。蜡样芽孢杆菌Ct3对高达125 mg/L的毒死蜱具有抗性，并在pH值为8的条件下于8天内成功降解了88%的毒死蜱。蜡样芽孢杆菌Ct3能耐受约30 - 40°C的温度，这对原位生物修复来说是个好迹象。对绿色堆肥、农家肥和稻壳进行了测试，方差分析（P < 0.05）和Plackett - Burman设计结果表明，农家肥对降解有显著影响。它缩短了滞后期，并使最大降解率达到88%。接种量是一个具有统计学意义（P < 0.05）的因素，接种量低于10（CFU/g）时会出现4 - 6天的滞后期。米氏方程模型结果如下：R = 0.9919，V = 18.8，K = 121.4，V/K = 0.1546。气相色谱 - 质谱联用（GC - MS）研究表明，毒死蜱首先转化为二乙基硫代磷酸和3,5,6 - 三氯 - 2 - 吡啶醇（TCP）。随后，TCP环被打破，并且它完全矿化，没有任何有毒副产物。采用Plackett - Burman设计来研究五个因素的影响。实验值与预测值之间的相关系数（R）为0.94。采用中心复合设计（CBD），其设计矩阵包含31个毒死蜱降解的预测值和实验值，“失拟P值”为“0.00”。得到的回归系数R = 0.93，这表明实验值和预测值拟合度很高。在CBD/方差分析和表面响应图中突出显示的最显著因素是毒死蜱浓度和接种量。蜡样芽孢杆菌Ct3能有效降解毒死蜱，并可成功用于毒死蜱污染土壤的生物修复。
