title: Production of humic substances through coal-solubilizing bacteria.
abstract: In this paper, the production of humic substances (HS) through the bacterial solubilization of low rank coal (LRC) was evaluated. The evaluation was carried out by 19 bacterial strains isolated in microenvironments with high contents of coal wastes. The biotransformed LRC and the HS produced were quantified in vitro in a liquid growth medium. The humic acids (HA) obtained from the most active bacterial strain were characterized via elemental composition (C, H, N, O), IR analyses, and the E4/E6 ratio; they were then compared with the HA extracted chemically using NaOH. There was LRC biotransformation ranged from 25 to 37%, and HS production ranged from 127 to 3100 mg . L(-1). More activity was detected in the isolated strains of Bacillus mycoides, Microbacterium sp, Acinetobacter sp, and Enterobacter aerogenes. The HA produced by B. mycoides had an IR spectrum and an E4/E6 ratio similar to those of the HA extracted with NAOH, but their elemental composition and their degree of aromatic condensation was different. Results suggest that these bacteria can be used to exploit the LRC resulting from coal mining activities and thus produce HS in order to improve the content of humified organic matter in soils.
authors.affiliation: Laboratory of Environmental and Agricultural Microbiology Universidad Popular del Cesar Campus Sabanas, Valledupar Colombia Laboratory of Environmental and Agricultural Microbiology, Universidad Popular del Cesar, Campus Sabanas, Valledupar, Colombia. ; Faculty of Basic Science Universidad de La Guajira Riohacha Colombia Faculty of Basic Science, Universidad de La Guajira, Riohacha, Colombia.
authors.forename: Nelson
authors.initials: N
authors.lastname: Valero
authors.affiliation: Laboratory of Environmental and Agricultural Microbiology Universidad Popular del Cesar Campus Sabanas, Valledupar Colombia Laboratory of Environmental and Agricultural Microbiology, Universidad Popular del Cesar, Campus Sabanas, Valledupar, Colombia.
authors.forename: Liliana
authors.initials: L
authors.lastname: Gómez
authors.affiliation: Laboratory of Environmental and Agricultural Microbiology Universidad Popular del Cesar Campus Sabanas, Valledupar Colombia Laboratory of Environmental and Agricultural Microbiology, Universidad Popular del Cesar, Campus Sabanas, Valledupar, Colombia.
authors.forename: Manuel
authors.initials: M
authors.lastname: Pantoja
authors.affiliation: Soil Physics Laboratory Universidad Nacional de Colombia Medellín Colombia Soil Physics Laboratory, Universidad Nacional de Colombia, Medellín, Colombia.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Ramírez
mesh_terms: D001419:Bacteria / Q000302:isolation & purification / Q000378:metabolism*; D001711:Biotransformation; D003031:Coal; D004602:Elements; D004783:Environmental Microbiology; D006812:Humic Substances / Q000032:analysis*
chemical_list: D003031:Coal; D004602:Elements; D006812:Humic Substances
keywords: Acinetobacter baumannii; Bacillus mycoides; Enterobacter aerogenes; Microbacterium sp; low rank coal