"Degradation of fat by a bioaugmentation product comprising of Bacillus spp. before and after the addition of a Pseudomonas sp."

Abstract

A bioaugmentation product, BFL, comprising strains of the genus Bacillus, was evaluated for its ability to degrade fat in laboratory-scale experiments. Addition of a Pseudomonas putida strain CP1 to the commercial mixed population (BFL-CP1) was tested for optimization of fat degradation. Experiments were carried out in aerobic batch culture, at 30°C and 150 rpm for 13 days incubation. A minimal medium and an enriched nutrient medium were investigated supplemented with 1% (w/v) butter. Fat removal was determined gravimetrically and the lipid content was analyzed using thin layer chromatography (TLC) and gas chromatography (GC). No degradation of butter by the product was recorded after 13 days of incubation, while up to 97% degradation was observed by BFL-CP1. All the Bacillus isolates produced lipase but not the Pseudomonas putida. TLC and GC results suggested that while the Bacillus spp. hydrolyzed the fat to fatty acids and glycerol, complete metabolism of the breakdown products only took place in the presence of the Pseudomonad sp. A citrate buffer was used to investigate fat removal by BFL-CP1in low and stable pH using citrated minimal buffer. Similar fat removal was observed. The use of citrated minimal buffer caused flocculation of the mixed culture, a phenomenon desirable for fats, oils and grease (FOG) degradation in grease traps.

Practical applications: The bioaugmentation product, BFL, comprising strains of the genus Bacillus, only promoted high fat removal in a few days incubation after the addition of a Pseudomonas putida strain CP1. Analysis of the remaining fat suggested a cooperative activity between the Bacillus spp., which hydrolyzed the fat to fatty acids and glycerol, and the Pseudomonas putida CP1, which assimilated the released fatty acids. Formation of flocs were observed when the inoculum was tested under different environmental conditions with low pH. This phenomenon is desirable and along with the high degradative ability of the that new inoculum, it showed good potential for use in the treatment of FOG in grease traps.

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