In recent years, the health risks of cooking oil fumes have been widely concerning. Since formaldehyde is one of the major pollutants emitted from cooking oil fumes, the degradation of formaldehyde should be investigated. Due to the advances and innovations in the degradation of pollutants, biodegradation was evaluated in this research. In this study, we screened out the strain of XF-1, which can degrade formaldehyde from cooking oil fume condensates. The strain of XF-1 was identified as Bacillus amyloliquefaciens sp. by a sequence analysis combing morphology, physiological, and biochemical experiments. The degrading characteristics of the strain were further studied. In the medium with a formaldehyde concentration of 100 mg·L-1, the efficiency of XF-1 for degrading formaldehyde was 95.80% within 34 h. When the initial concentration of formaldehyde was <300 mg·L-1, the XF-1 strain could completely degrade the formaldehyde within 120 h. When the formaldehyde concentration was 800 mg·L-1, the degradation rate of the XF-1 strain reached 73.01% at 96 h. The maximum tolerated concentration of formaldehyde was 1500 mg·L-1. According to a single factor experiment (pH, inoculation amount, formaldehyde concentration, and temperature), the influence of each factor on the degradation of formaldehyde was studied. The optimal growth condition of the strain was 30℃ at pH 6 with an inoculum amount of 10%. The degradation specificity of formaldehyde was studied by comparing it with that of other bacillus species. The results showed that XF-1 strain was specific with regard to the function of degrading formaldehyde and was able to withstand a high oil environment. The maximum tolerable oil concentration of XF-1 was 900 g·L-1. By analyzing the extracellular metabolites, it was determined that the metabolic pathway of formaldehyde degradation was the RuMP assimilation pathway. In this paper, a strain of formaldehyde degrading bacteria that was also resistant to oil was screened out and its metabolic mechanism was studied. The results indicated that the bacteria had broad application prospects in the treatment of formaldehyde emitted from cooking oil fumes.
Keywords: Bacillus; degrading characteristics; formaldehyde; isolation and identification; metabolic mechanism.