Burkholderia cepacia (B. cepacia) is an aerobic Gram-negative bacillus found in various aquatic environments and can cause food contamination. We investigated the photodynamic antibacterial effects of food additive curcumin combined with EDTA on B. cepacia. We found a ~4-log reduction in B. cepacia viability when photo-irradiated with curcumin at 50 μM by blue LED light (16 mW/cm2) for 30 min with 0.4% (w/v) EDTA. Moreover, the bacterial morphological alterations and the leakage of intracellular contents were observed after photodynamic treatment. There were also obvious genomic DNA cleavage and a general loss of bacterial proteins assigned to large-scale protein degradation after photodynamic inactivation treatment. Collectively, curcumin in combination with EDTA illuminated by blue LED is a potential candidate for photodynamic inactivation of B. cepacia.
An extractive fermentation technique was developed using a thermoseparating reagent to form a two-phase system for simultaneous cell cultivation and downstream processing of extracellular Burkholderia cepacia lipase. A 10% (w/w) solution of ethylene oxide-propylene oxide (EOPO) with a molecular mass of 3900 g/mol and pH 8.5, a 200 rpm speed, and 30 °C were selected as the optimal conditions for lipase production (55 U/ml). Repetitive batch fermentation was performed by continuous replacement of the top phase every 24h, which resulted in an average cell growth mass of 4.7 g/L for 10 extractive batches over 240 h. In scaling-up the process, a bench-scale bioreactor was tested under the conditions that had been optimized in flasks. The production rate and recovery yield were higher in the bioreactor compared to fermentation performed in flasks.