ABSTRACT
Abstract Carbaryl is an important and widely used insecticide that pollutes soil and water systems. Bacteria from the local soil ecosystem of the Gaza Strip capable of utilizing carbaryl as the sole source of carbon and nitrogen were isolated and identified as belonging to Bacillus, Morganella, Pseudomonas, Aeromonas and Corynebacterium genera. Carbaryl biodegradation by Bacillus, Morganella and Corynebacterium isolates was analyzed in minimal liquid media supplemented with carbaryl as the only source of carbon and nitrogen. Bacillus and Morganella exhibited 94.6% and 87.3% carbaryl degradation, respectively, while Corynebacterium showed only moderate carbaryl degradation at 48.8%. These results indicate that bacterial isolates from a local soil ecosystem in the Gaza Strip are able to degrade carbaryl and can be used to decrease the risk of environmental contamination by this insecticide.
Subject(s)
Bacteria/classification , Bacteria/genetics , Bacteria/isolation & purification , Bacteria/metabolism , Biodegradation, Environmental/classification , Biodegradation, Environmental/genetics , Biodegradation, Environmental/isolation & purification , Biodegradation, Environmental/metabolism , Carbaryl/classification , Carbaryl/genetics , Carbaryl/isolation & purification , Carbaryl/metabolism , Ecosystem/classification , Ecosystem/genetics , Ecosystem/isolation & purification , Ecosystem/metabolism , Insecticides/classification , Insecticides/genetics , Insecticides/isolation & purification , Insecticides/metabolism , Middle East/classification , Middle East/genetics , Middle East/isolation & purification , Middle East/metabolism , Soil Microbiology/classification , Soil Microbiology/genetics , Soil Microbiology/isolation & purification , Soil Microbiology/metabolism , Soil Pollutants/classification , Soil Pollutants/genetics , Soil Pollutants/isolation & purification , Soil Pollutants/metabolismABSTRACT
Carbaryl, an N-methyl carbamate insecticide, is used in India to control foliar insects, but, due to soil contamination, it also adversely affects non-target organisms such as earthworms. This paper deals with the toxic effects of carbaryl on the behavioural and reproductive profiles of the earthworm, Metaphire posthuma. Locomotion and geotaxis were significantly affected, even after a 20-minute exposure to 0.125ppm carbaryl. The hatching of cocoons was altered at 0.5ppm, whereas cocoon production was retarded even at 0.125ppm carbaryl. No cocoon production was observed at 2.0ppm carbaryl. Sperm head abnormalities were reported even at the lowest test concentration of 0.125ppm. Wavy head abnormalities were observed at 0.125ppm carbaryl, whereas at 0.25ppm and 0.5ppm, the sperm heads became amorphous and the head nucleus was turned into granules deposited within the wavy head. It is concluded that the earthworm could be used as an ecosystem model for the initial toxicity testing of environmental pollutants.
