Synergetic degradation of waste oil by constructed bacterial consortium for rapid in-situ reduction of kitchen waste

Traditional composting of kitchen waste (KW) is cost- and time-intensive, requiring procedures of collection, transport and composing. Consequently, the direct in-situ reduction of KW via treatment at the point of collection is gaining increasing attention. However, high oil content of KW causes separation and degradation issues due to its low bioavailability and the hydrophobicity, and therefore greatly limiting the direct application of in-situ methods for mass reduction. To overcome this, a bacterial consortium of Pseudomonas putida and Bacillus amyloliquefaciens was constructed, which exhibited a synergistically improved oil degrading ability for lipase-catalyzed hydrolysis, fatty acids β-oxidation, biosurfactant production and surface tension reduction, and the degradation ratio reached 58.96% within 48 h when the initial KW oil concentration was 8.0%. The in-situ aerobic digestion of KW was further performed in a 20-L stirred-tank reactor, the content of KW oil (34.72 ± 2.05% of total solids, w/w) was rapidly decreased with a simultaneous increase in both lipase activity and in microbial cell numbers, and the degradation ratio reached 57.38%. The synergetic effect of the two strains including B. amyloliquefaciens and P. putida promoted the decomposition process of KW oil, which also paved the way for an efficient degradation strategy to support the application potential of in-situ microbial reduction of KW.