[Microbial succession on lignite along with weathering]

Six different weathered lignite samples were examined by scanning electron microscopy. Few microorganisms were observed on lignit just excavated and only spores and short hyphae were observed on lignite samples excavated 5 months, 1 year and 4 years before sampling. When lignite samples were moistened with distilled water and incubated for 10 days, actinomycetes proliferated significantly on lignite samples that were just excavated or excavated 5 months before sampling. The growth of bacteria was observed on lignite samples excavated 1 year before sampling. Fungi increased in length and in number on lignite samples excavated 4 years before sampling. These findings of microbial succession on lignite samples along with weathering were consistent with results of the plate count method; actinomycetes are the first colonizers, then bacteria and fungi are the last degrader. The dominant microorganisms were Actinosynnema sp., Streptomyces sp. and Nocardia sp. among actinomycetes, two Arthrobacter sp. among bacteria and two Aspergillus sp. among fungi.