BIOFILM FORMATION OF HYDROCARBON-DEGRADING MICROBIAL COMMUNITY ON POROUS MEDIA FIXED BED BIOREACTORS

MARCELA SEPÚLVEDA; NELDA L. OLIVERA; FLORENCIA REVUELTA; ROSANA POLIFRONI; MARINA L. NIEVAS EL MAKTE

Río de Janeiro

Simposio; Latin American Biodeterioration and Biodegradation Symposium; 2016

International Biodeterioration & Biodegradation Society

BIOFILM FORMATION OF HYDROCARBON-DEGRADING MICROBIAL COMMUNITY ON POROUS MEDIA FIXED BED BIOREACTORSSepúlveda M.A.1; Polifroni R1, Revuelta F.2, Olivera N.L.3, Nievas El Makte M.L.1,21 CESIMAR Centro Nacional Patagónico (CONICET-CENPAT), Bv. Brown 2915, Puerto Madryn;2 Universidad Tecnológica Nacional - Facultad Regional Chubut, Av. del Trabajo 1536, Puerto Madryn.3 IPEEC Centro Nacional Patagónico (CONICET-CENPAT), Bv. Brown 2915, Puerto Madryn;Keywords: biofilm, hydrocarbon mineralization, fixed-bed bioreactorAbstractMicrobial biofilms are natural conglomerates of microorganisms that group together getting competitive and survival advantages in comparison with planktonic cells. Hydrocarbon-degrading microbial communities in biofilms have wide technological application for bioremediation of impacted sites and wastewater treatment. The aim of this work was to evaluate the biofilm time course formation of a marine microbial community able to mineralize hydrocarbons in packed bioreactors. A microbial suspension of hydrocarbon polluted intertidal sediments from the Puerto Madryn´s port (Patagonia Argentina) was used as inoculum. The microbial suspension with crude oil as the only carbon source was recirculated 14 days through four fixed bed reactors (45 mm id, 500 mm length, 0.3 void fraction) filled with gravel particles (1000 - 2000 m). Then an aerated marine mineral medium with 1000 ppm crude oil was recirculated through the reactor at 1.8 10-4 m/s superficial velocity. Samples of gravel particles were withdrawn periodically and the biofilm formation was evaluated by the crystal violet technique. Microbial count of petroleum and naphthalene degrading bacteria were assessed and the potential of hydrocarbon mineralization was determined by respirometric method Microresp? using crude oil, n-hexadecane and phenanthrene as substrates. The profile of the taxonomic dominant members of the community was assessed by extracting DNA and analyzing by PCR-DGGE. The abundance of petroleum- and naphthalene-degrading microorganisms attached to gravel reached their highest values after 7 days of incubation (1.5 x 10 8 MPN g-dw-1 and 5.9 x 107 MPN g-dw-1, respectively), then decreasing up to 5.6 x 106 MPN g-dw-1 and 3.5 x 105 MPN g-dw-1 at day 14 respectively, and since then they remained constant up to the end of the experiment. The adhesion of microorganisms to gravel occurred since day 7 as determine by MPN count, but biofilm detection started after 20 days. The microorganisms immobilized in gravel were able to mineralize n-hexadecane since day 7 days, whereas mineralization of crude oil and phenanthrene were detected after the fifth week. The four reactors?s microbial communities had reproducible DGGE profiles, showing less diversity than the sediment community used as inoculum. Finally, the results demonstrated that a biofilm of marine microbial community was formed in 35 days with the capability to mineralize a wide range of hydrocarbons, with higher metabolic capability associated with biofilm development. These results are relevant for treatment processes of hydrocarbon-containing wastewater.