Biosolubilization of low-rank coal by the newly isolated strain Streptomyces fulvissimus K59

Lignite, as low rank coal (LRC) has some disadvantages compared to hard coal, its use is limited. Therefore alternative and ecological conversion methods are being sought. Microbiological liquefaction of lignite is a clean and cost-effective technology for the treatment of solid waste resources, that allows for recovery of complex aromatic compounds from LRC. These can be further converted into products of agricultural relevance, with added value. In the presented studies 10 microbial strains were isolated from coal samples. One of the strains, identified as Streptomyces fulvissimus K59 was selected and applied in biosolubilization of coal in a liquid culture. Capacity of the K59 isolate for coal decomposition was tested in mineral medium, in modified yeast extractpeptone-glucose medium (YPG) containing 1% unprocessed carbon and in YPG with lignite treated using 2 N, 5 N and 8 N HNO3. A Plackett-Burman design was applied for the screening of influential process parameters. The most efficient biosolubilization process was achieved after substrate processing with 5 N HNO3, in the presence of 10 g/L sucrose and 50 g/L lignite, where the resultant concentration of biosolubilized lignite was 15 times higher as compared to the results obtained using crude coal.