Biodegrading biofilms on biopolymeric sorbent scaffolds

Abstract

Abstract Immobilization of hydrocarbon-degrading microorganisms on biodegradable adsorbing scaffolds significantly promotes bioremediation processes in fresh and sea water . Recently low cost, ecofriendly bioremediation devices based on polycaprolactone and polylactic acid membranes hosting a biodegrading bacterial biofilm were obtained [1]. The resulting biosorbent biodegrading biofilms simultaneously adsorbed 100 % of spilled oil and biodegraded more than 66% of it over 10 days; biodegradation was 23% higher than that obtained using free living bacteria [1]. In this work, adhesion, survival and HC-biodegradation ability of these biodegrading biofilms was tested in long term experiments and under dry conditions mimicking smog-contaminated air. The HC-degrading Actinobacteria Nocardia cyriacigeorgica strain SoB, Gordonia amicalis strain SoCg [2], and the marine hydrocarbonoclastic Alcanivorax borkumensis strain AU3-AA-7 [3] were immobilized on polylactic acid (PLA) and polycaprolactone (PCL) membranes prepared by electrospinning [1]. The capacity of adhesion and proliferation of bacterial cells into the biopolymers were evaluated using scanning electron microscopy (SEM) after 5, 10, 15 and 30 days. PLA and PCL nanofibers appear almost completely covered by a complex three dimensional bacterial film for all the strains. Total biomass (estimated as total dsDNA) confirmed biofilm growth up to 30 days incubation. Viable plate counts and Gas Chromatography-FID analysis revealed that the biofilm was vital and functional after 30 days. Exposing a 15-day liquid incubated biofilms to further 15 days in a hexadecane-saturated air chamber reduced by 100fold plate count yeld. Bibliography: [1] Catania V., Lopresti F., Cappello S., Scaffaro R. and Quatrini P. (2020). N Biotechnol, 58, 25-31. [2] Quatrini P., Scaglione G., De Pasquale C., Riela S. and Puglia A.M. (2008). J. Appl. Microbiol.,104(1),251-259. [3] Catania V., Santisi S., Signa G., Vizzini S., Mazzola A., Cappello S.,. Yakimov M.M. and Quatrini P. (2015). Mar. Pollut. Bull., 99(1-2), 138-149. Acknowledgments: Elisa Maria Petta’s PhD grant is financed by PON "Research and Innovation" 2014-2020, Axis IV "Education and research for recovery" Action IV.5 "PhDs on green issues”