Department of Botany, Gauhati University.
J Gen Appl Microbiol. 2020 Sep 30;66(4):207-214. doi: 10.2323/jgam.2019.09.001. Epub 2020 Jan 24.
Cyanobacteria are an important component in the rice field ecosystem and are a well known source of natural biofertilizer. Pesticidal application for the control of pests in rice field soil has led to several environmental problems, and poses a great threat to these beneficial microorganisms. Studies on the impact of pesticides on the diazotrophic growth and survivability of these microorganisms have recently gained much attention. The present paper describes the effects of an iterated use of the insecticide deltamethrin (2.8% EC) on the growth and nitrogen fixation capacity of the filamentous cyanobacterium Calothrix sp. (strain GUEco 1002). This organism has shown a varying degree of sensitivity to the insecticide. For evaluating the deltamethrin toxicity, the test organism was subjected to varying concentrations of deltamethrin i.e. 17.5 ppm, 35 ppm, 70 ppm and 140 ppm based upon LC for 20 days. The data obtained in the laboratory revealed that the treatment of the test organism with deltamethrin (17.5-140 ppm) negatively affected its growth, pigments, protein and nitrogen content in a time dose dependent manner. In contrast, carbohydrate content significantly increased with increasing concentrations of deltamethrin, this effect being more prominent at 140 ppm treatment (38%). At this high level (140 ppm), the test organism showed a significant decrease in dry weight biomass (46%), chlorophyll-a (72%), carotenoids (57%), phycocyanin (67%), protein (69%) and nitrogen content (61%) over the control. A little, but insignificant, stimulatory effect on nitrogen content was recorded at 17.5 ppm of the insecticide which however, was the opposite in the case of growth, pigments, carbohydrate and protein content.
蓝藻是稻田生态系统的重要组成部分，也是一种著名的天然生物肥料来源。为了控制稻田土壤中的害虫而使用农药，这导致了一些环境问题，并对这些有益微生物构成了巨大威胁。最近，人们对农药对这些固氮微生物的生长和生存能力的影响进行了大量研究。本文描述了反复使用杀虫剂溴氰菊酯（2.8% EC）对丝状蓝藻 Calothrix sp.（菌株 GUEco 1002）的生长和固氮能力的影响。该生物对杀虫剂表现出不同程度的敏感性。为了评估溴氰菊酯的毒性，将测试生物置于不同浓度的溴氰菊酯中，即基于 LC 的 17.5 ppm、35 ppm、70 ppm 和 140 ppm，持续 20 天。实验室获得的数据表明，用溴氰菊酯（17.5-140 ppm）处理测试生物会对其生长、色素、蛋白质和氮含量产生负面影响，这种影响随时间和剂量而变化。相比之下，随着溴氰菊酯浓度的增加，碳水化合物含量显著增加，在 140 ppm 处理下（38%）效果更为明显。在这个高浓度（140 ppm）下，测试生物的干重生物量（46%）、叶绿素-a（72%）、类胡萝卜素（57%）、藻蓝蛋白（67%）、蛋白质（69%）和氮含量（61%）与对照相比显著下降。在杀虫剂 17.5 ppm 时，对氮含量有一点但不显著的刺激作用，但在生长、色素、碳水化合物和蛋白质含量方面则相反。
