Production of a halotolerant biofilm from green coffee beans immobilized on loofah fiber (Luffa cylindrica) and its effect on phenanthrene degradation in seawater

Abstract

ABSTRACTA biofilm developed from low quality green coffee beans was tested for its capacity to degrade the polynuclear aromatic hydrocarbon (PAH), phenanthrene (Phe), in seawater. Microorganisms were immobilized on two types of Luffa cylindrica (with three and four placental cavities), and the effects of moisture content (20, 30 and 40% of water holding capacity) and particle size (<0.42 mm, 0.42–0.86 mm and 0.86–2.0 mm) of green coffee beans on microbial activity were considered. Biofilm growth determined by respirometry showed a highest microbial activity at a moisture content of 40% and particle size of 0.42–0.86 mm. The loofah fiber with three placental cavities showed the highest adherence of microorganisms. The kinetics of microbial growth in both seawater and distilled water and the scanning electron microscopies indicated that the microorganisms associated with green coffee beans are halotolerant. In fact, I-GCB-SW-G biofilm degraded 67.56% of Phe (50 mg L−1) in seawater, at a significantly higher rate than in distilled water (I-GCB-DW-W).