The role of hydrocarbon-oxidizing bacteria Acinetobacter pitti. RKB1 and Bacillus sp. RKB2 in the processes of bio-solubilization of brown coal from the Kiyakty coal deposit (Karaganda, Kazakhstan)

Abstract

According to the obtained results, it was established that two strains from five hydrocarbon-destroying bacteria tested on coal – Acinetobacter pitti. RKB1 and Bacillus sp. RKB2 that can solubilize pure
brown and pre-treated with nitric acid coal. It was established that 25-28% of raw coal was dissolved in
dry weight within 30 days. Pretreatment of coal with nitric acid increased the efficiency of this process
by 52% when Bacillus sp. RKB2 used. The extracellular solubility of coal with the usage of microbial
strains decreased pH slightly, which indicates the contribution of some alkaline substances to the dissolution of lignite. However, the biosolubilization mechanisms of lignite of two strains were different.
These can be either active extracellular substances that synthesized with Acinetobacter pitti. RKB1 or it
can be some enzymes yielded with Bacillus sp. RKB2. Elemental analysis of coals that pretreated with
HNO
3 and biosolubilization products formed under the action of Acinetobacter pitti. RKB1, or Bacillus
sp. RKB2 showed significant differences between lignite and products that formed during the microbial
conversion of coal.
Key words: Lignite, leonardite, biosolubilization.