Characterization of extracellular and cell bound biosurfactants produced by Aneurinibacillus aneurinilyticus isolated from commercial corn steep liquor

摘要

The presence of biosurfactants produced by a Bacillus strain in corn steep liquor (CSL), a wastewater stream of the corn milling process, has been recently discovered. However, the species responsible for their production has not been identified at the moment. Therefore, in this work, the Bacillus strain isolated from CSL, with capacity to produce biosurfactants, was subjected to amplification and sequence analysis of the 16S rRNA, being identified as Aneurinibacillus aneurinilyticus. This strain has been proved to be endospore forming and thermophile, what would explain its presence in the commercial CSL. It was observed that the strain under evaluation has the ability to produce both cell-bound and extracellular biosurfactant extracts, which were characterized in this work. The electrospray ionization mass spectrometry (ESI) analysis of the biosurfactant extracts revealed that the extra cellular biosurfactant produced by Aneurinibacillus aneurinilyticus is composed by a mixture of lipopeptides, containing C16 and C18 fatty acids and amino acids, including valine, phenylalanine, proline, cysteine, histidine, aspartic acid/asparagine, alanine, glycine, leucine/isoleucine, with biomarkers between 1025-458 m/z. Conversely, the cell-bound biosurfactant extract produced by Aneurinibacillus aneurinilyticus was composed by the cyclic decapeptide gramicidin S, with a characteristic peak at 571 m/z, and lipopeptides with characteristic peaks between 1034-705 m/z, containing alanine, glycine, cysteine, serine, proline, aspartic acid/asparagine, similarly to the amino acid sequence of the extracellular biosurfactant extract.