Effect of fermentation conditions on the enterotoxigenicity, cytotoxicity and pesticidal activity of Bacillus thuringiensis strains isolated in Taiwan.
A total of 75 Bacillus thuringiensis strains, among them 62 of Taiwan's microbiota, were screened for their enterotoxin genes, hemolysin BL activity and cytotoxicity. All the strains harbored enterotoxin genes and were cytotoxic to the cultivated Chinese hamster ovary (CHO) cells. The hemolysin BL and cytotoxicity titers of the B. thuringiensis culture in casitone yeast sucrose (CYS) broth were lower than those in brain heart infusion (BHI) broth, and when the B. thuringiensis strains were cultivated in CYS broth for 5 days, no cytotoxicity was detected. The spores and crystal toxins collected from 40 isolates showed high levels of insecticidal activity against Plutella xylostella. All strains exhibiting low cytotoxicity also had low pesticidal activity. Our study demonstrated that it is difficult to find B. thuringiensis strains that are both effective against insect targets and do not produce enterotoxins or cytotoxic effects in CHO cells. However, it is possible to avoid or reduce unwanted properties, but not the insecticidal activity, of some B. thuringiensis preparations by alteration of culture media and conditions.
Pang
Jen-Chieh
JC
Department of Biotechnology, Van-Nung University, Chung-Li, Taoyuan County 320, Taiwan, ROC.
Chen
Ming-Lun
ML
Ho
Yi-Cheng
YC
Yang
Chi-Yea
CY
Tzeng
Ching-Chou
CC
Kao
Suey-Sheng
SS
Tsen
Hau-Yang
HY
D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D016466:CHO Cells; D002364:Caseins / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D005285:Fermentation; D006460:Hemolysin Proteins / Q000737:chemistry; D007313:Insecta; D007306:Insecticides / Q000737:chemistry; D010572:Pest Control, Biological / Q000379:methods*; D016133:Polymerase Chain Reaction; D013045:Species Specificity; D013395:Sucrose / Q000494:pharmacology; D013624:Taiwan
D002364:Caseins; D006460:Hemolysin Proteins; D007306:Insecticides; D013395:Sucrose; C475729:casein hydrolysate