Biotransformation of the antibiotic agent cephadroxyl and the synthetic dye Reactive Black 5 by Leptosphaerulina sp. immobilised on Luffa (Luffa cylindrica) sponge

In the present work, immobilisation of Leptosphaerulina sp., a Colombian native fungus, improved the biotransformation of pollutants (Remazol black 5 (RB5) dye and cephadroxyl (CPD) antibiotic) in aqueous systems. Four different natural immobilisation matrices (charcoal, luffa sponge, wood chips and cork) were tested in order to select the most suitable for Leptosphaerulina sp. biomass augmentation. Luffa sponge was selected qualitatively as the most appropriate material for the immobilisation of Leptosphaerulina sp. CPD and RB5 biotransformation was performed with immobilised and suspended Leptosphaerulina sp. cultures on luffa sponge. The luffa sponge-immobilised fungus exhibited a considerable removal of CPD (similar to 100%) and RB5 (91.9%). The luffa sponge-immobilised Leptosphaerulina sp. achieved a higher CPD removal than the suspended cultures (similar to 100% vs 94.4%, respectively, on day 15). RB5 experiments revealed a higher removal (91.9% for immobilised fungus vs 87% for suspended fungus, on day 15) and a faster transformation of RB5 in luffa sponge-immobilised cultures than that of free cultures (26.3 decolourisation % per day for immobilised cultures vs 18.2 decolourisation % per day for suspended cultures). Additionally, luffa sponge immobilisation also improved Leptosphaerulina sp. production of laccase (Lac) and manganese peroxidase (MnP) (e.g. at day 3, Lac and MnP in immobilised culture were 84% and 76%, respectively, higher than suspended culture during CDP removal, and 83% and 5% in bio-treatment of RB5). These results evidenced the potential of Luffa sponge-immobilised Leptosphaerulina sp. as a strategy to enhance the biodegradation of recalcitrant compounds, to facilitate biomass recycling and to be used in the process scale-up.