Bacillus thuringiensis is a disease-causing bacterium in insects that is used to control insect pests that attack crops, both crops and horticultural crops. This bacterium can be isolated from plant residues that have become compost, infected insects, and soil. Isolation was carried out to take bacteria from  their natural environment and grow them in artificial media. In swamps there are important microorganisms  involved  in  the  decomposition  of  organic matter, the microbes that play a role consist of fungi and bacteria, such as those found in rice plantations in Barito Kuala swamps which include the Actinomycetes, Bacillus, Cromobacterium, and Pseudomonas bacteria groups. B. thuringiensis is widely distributed in nature but is rare due to the many different Bacillus isolates.  Therefore, it is  necessary  to conduct  research  to  determine  the presence of B. thuringiensis in plant  root areas in more specific soils to increase the possibility of finding B. thuringiensis. This  study aims to  determine  the number of  B. thuringiensis isolates obtained in type B tidal land ecosystems. This  research  was  conducted  from  December  2021  to June 2022  at  the Integrated Laboratory and  Production  Laboratory, Department of  Agroecotechnology , Faculty  of Agriculture,  University of Lambung  Mangkurat. This  research  uses a  descriptive  method. Soil collection was  carried  out  by  purposive  sampling (sampling  technique  with certain considerations) in the planting area in tidal land type B. Soil samples were taken from 3 places as a comparison, namely in the rice planting area, orange planting and banana planting area B. The  parameters  observed  in  this  study  were  the  number  of  colonies, the macroscopic and microscopic shape characteristics of the bacteria, the gram of  bacteria, and  the test of  the killing power of bacteria against P.xylostella insects. Based on the parameters that have been observed, the highest number of colonies was found in citrus plantation samples of 98 colonies.

Keywords:

Isolation, Bacillus thuringiensis.