Compatibility of <i>Bacillus thuringiensis</i> AK08 and Streptomycin Sulfate 20% in Inhibiting the Growth of <i>Enterobacter</i> sp. in Vitro

Abstract Streptomycin sulfate is an active ingredient in synthetic bactericides with the trademark Agrept which is usually used to control plant diseases, including patchouli wilt disease caused by Enterobacter Sp. The use of chemicals causes residues and negative impacts on living things. To reduce the use of chemicals, a combination of chemical methods with biological control techniques such as the antagonistic B. thuringiensis. This bacterium has the ability to control various pathogens that cause disease in plants. The compatibility test between B. thuringiensis and streptomycin sulfate has used a non-factorial completely randomized design (CRD), 5 treatments, and 4 replications. The results showed that the concentration chosen for the compatibility test was 50 ppm because B. thuringiensis was able to grow more optimally compared to other concentrations. The percentage of inhibition from single and combination streptomycin sulfate treatment with B. thuringiensis showed the highest levels in 7 HSIs, which were 70.25% and 75.57%. Meanwhile, the lowest percentage of inhibition was seen in the treatment of B. thuringiensis alone, around 56.04%. From this research, it can be concluded that the combination between B. thuringiensis and streptomycin sulfate, both are compatible but do not show an increase in synergy in inhibiting Enterobacter sp.