Obtenção de consórcios microbianos produtores de biossurfactantes e biodegradadores de hidrocarboneto recalcitrantes

Abstract

The residues produced by the petrochemical industry represent a high environmental risk, but biotechnological tools offer promising alternatives for the treatment of these residues. Through the production of biosurfactants as adjuvants, microorganisms clean up the waste by degrading the hydrocarbons present in the waste. Four consortia were obtained from samples of drilling residues and production water (AP) from an oil reservoir in order to select microbial communities capable of degrading oil and synthesizing biosurfactants. The two consortia from the AP, one enriched in Yeast Extract Peptone Dextrose medium (YPD consortium) and the other using only the Bushnell-Haas mineral medium (BH consortium) with oil as a substrate. Two other consortia from drilling rock were enriched in rich medium Luria Bertani (LB), consortia R1 and R2. Sequences of metagenomic DNA showed that the consortia enriched in LB and YPD showed greater alpha diversity and taxonomic redundancy, while the BH consortium is predominantly composed of members of the genus Brevibacillus. The BH consortium was enriched with genes from the serrawettin, trehalolipid and ramnolipid pathways for the synthesis of low molecular weight biosurfactants. These biosurfactants give the BH consortium a high cellular hydrophobicity and formation of stable emulsions. While the consortia YPD, R1 and R2 have a greater abundance of recalcitrant hydrocarbon degradation genes and only the biosynthesis pathways of biosurfactants pultisolvins and plipastatin were selected in these consortia that give them a greater reduction in interfacial tension. Despite these differences between consortia, oil biodegradation analyses carried out by gas chromatography showed few significant differences in relation to the degradation rates of aliphatic and polycyclic aromatic hydrocarbons (PAHs). These data suggest that the enrichment of biosurfactant genes in the BH consortium could promote a more efficient degradation of hydrocarbons, despite their lower taxonomic diversity compared to the consortium enriched in YPD, R1 and R2. Together, these results showed that cultivation in minimal medium supplemented with medium API oil (American Petroleum Institute) was an efficient strategy in the selection of microorganisms that produce biosurfactants and degradation of compounds that are difficult to degrade (recalcitrants). Therefore, they evidenced the biotechnological potential of these consortia in the prospecting of genes and organisms for the treatment of petrochemical residues and bioremediation of the impacted areas.