Pengaruh pH dan suhu terhadap produksi bioinsektisida oleh Bacillus thuringiensis var. Israelensis menggunakan substrat onggok tapioka

Abstract

A two level factorial composite experimental design was used in the study of pH and temperature effects on bioinsecticides production using Bacillus thuringiensis israeknsis (B.t.i.), The statistical analysis indicates the two factors were major variables in the bioinsecticides product. The temperatures (X1) that were used in this research were low level (25 0C) and high level (35 0C) and the pH values were 5,5 and 8. Two main parameters in the research were the growth of B. t. i. and bioinsecticide activity. Growth d B-t- i- was indicated by the value of mmimum growth rate, maximum biomass, time neededfor the formation of maximum biomass and substrates utilization of the medium cultivation. The results of the research indicated that maximum growth rate is influenced by temperature and pH The effect d temperature on the growth of B.t.i. was showed by numerous value : i.e maximum biomass at significance level of 84.16 percent, time neededfor the formation of maximum biomass at significance level of 76,67percent, substrates utilization at significance level of 72,65 percent and the effect of pH on time forming of maximum biomass at significance level of 75,25 percent. Bioinsecticides activity was influenced by temperature at significance level of 97,i I percent and by pH at significance level of 96,95percent