Association of the level of mosquito larvicidal activity with the growth & sporulation in Bacillus sphaericus H-5a5b strains.
The role of growth and sporulation in the production of mosquito larvicidal factors in B. sphaericus H-5a5b strains was investigated using 6 strains that differed in their larvicidal activity. Among these, strain B64 produced maximum biomass (15.5 g/l by 29th h) while B45 and B85 yielded the least (12.8 g/l by 41st and 37th h respectively). Strains B43 and B42 reached the peak of viable cell count (4-6 x 10(10) cells/ml) 4 h earlier than B64 and 12 h earlier than the rest of the strains. Strains B42 and B43 produced higher number of heat resistant spores (4 x 10(8) spores/ml), while strains B45 and B57 produced the lowest numbers (2-4 x 10(5) spores/ml). Mosquitocidal toxin synthesis was noticed as early as the 5th and 9th h in the cultures of the strains B42 and B64 respectively while in those of other strains it was detected by the 13th h or later. The results indicated that generally the highly and moderately toxic strains grew faster and sporulated better than the poorly toxic ones.
Vector Control Research Centre (ICMR), Pondicherry.
A M
AM
Manonmani
S L
SL
Hoti
D000818:Animals; D001407:Bacillus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D009033:Culicidae / Q000254:growth & development*; D007814:Larva / Q000502:physiology; D013045:Species Specificity; D013170:Spores / Q000502:physiology*; D014118:Toxins, Biological / Q000378:metabolism
D014118:Toxins, Biological