Impact of a tandem treatment with a chemical oxidant and ligninolytic fungi augmentation on a petrochemical sludge

PELUFFO M.; DEL PANNO M.T.; DI CLEMENTE N; SAPARRAT, M.C.N.

Simposio; 17th International Symposium on Microbial Ecology; 2018

Petrochemical sludges are a serious environmental problem generated bypetroleum industry. The aim of this study was to analyse the combined effect ofthe chemical oxidation with ammonium persulfate (APS) followed by theaugmentation with ligninolytic fungi (Coriolopsisrigida LPSC-232and Grammothele subargentea LPSC-436)to remediate apetrochemical sludge. Microcosms of sludge and sand (1:3) were inoculated with each fungusseparately using wheat straw as carrier, under axenic and non-sterile conditions.After 30 and 60 daysof incubation, concentration of total hydrocarbons (IR) and alkane and PAH fractions(GC-FID) were determined. Dehydrogenase and laccase activities were evaluatedand the PCR-DGGE technique and DNA sequencing were applied to analyse the microbialstructure changes. Underaxenic conditions with or without previous APS treatment, both fungi altered theavailability of alkane and PAH fractions, probably due to the wheat straw degradation. Bothhydrocarbon fractions were not detected in presence of the sludge microbiota.Theoxidative treatment reduced 7% of the hydrocarbons content and 50% of themicrobial density. Besides, laccase activity was detected in inoculatedmicrocosms with both fungi in axenic and non-sterile conditions. Sequencinganalysis of 16SrDNA and 18SrDNA from the sludge microcosms allowed theidentification of the predominant taxa of the resilient populations, and thosethat settled after the bioaugmentation treatments.These results raise questionsabout the main contribution that ligninolytic fungi make in the transformationof petrochemical residues and their response to a previous oxidative chemicaltreatment, if applied, and to their interaction with indigenous sludge microbiota.