Physiological Changes in Wister Rats Induced with Bacillus Species Used as Bio Control Agent

Abstract

Aims: This work is aimed at toxicological effects of three Bacillus species employed as bio control agent against mosquito larvae in terrestrial environment. Study Design: Using animal model where weight, hematology and histopathology were considered. Place and Duration of Study: At Microbiology Department, Federal University of Technology, Akure, Nigeria, between December 2009 and February, 2010. Methodology: Twenty wistar rats weighing 180±0.61g were used and fed with mice feed and water ad libitum for one week to be acclimatize before dividing into four groups of five. Group 1 was the control and was allowed to normal rat feed and water only, group II – IV were subjected to daily single subcutaneous injection with 200l of 107cfu/ml cell dose of Bacillus thuringiensis, Bacillus subtilis and Bacillus cereus respectively for seven days. The rats were observed shortly after each dosing and thereafter twice daily for one week for general behavioral signs of toxicity and possibly mortality. Results: The rats infected with B. cereus lost weight by 3.8% during the period of study while those in the control, the treated with B. thuringiensis var. isrealensis and B. subtilis gained weight by an average of 3% of the initial weight. In the hematological analysis of the rats, there was significant difference (P<0.05) in values when compared with the control group. Though decrease in differential counts was observed in the rats injected with B. subtilis and B. thuringiensis, significant difference (P<0.05) in values was not observed with the control group. Histopatological examinations of the liver and small intestine of the rats treated with B. cereus had observable pathological changes when compared with control, B. thuringiensis and B. subtilis treat groups. Conclusion: There were no significant toxicological changes in the groups treated with B. subtilis and B. thuringiensis when compared with the control group. Based on these observations, it could be concluded that these bacterial species could be used as bio control agent in human environment without causing havoc to humans and animals.