Optimization of fermentation conditions of an acetaldehyde-degrading bacterium Bacillus velezensis LT-2

Abstract:

[Background] As an aldehyde pollutant, acetaldehyde widely exists in production and life. Compared with physical and chemical methods, biodegradation with great advantages has become a research hotspot. [Objective] To provide experimental resources for the microbial degradation of acetaldehyde, we screened out an acetaldehyde-degrading strain and optimized the fermentation conditions for degrading acetaldehyde. [Methods] After enrichment culture and acetaldehyde-degrading experiment, a strain with high acetaldehyde-degrading ability was obtained. Single factor tests (carbon source, nitrogen source, metal ions, temperature, rotational speed, inoculation amount, and initial pH) and multi-factor interaction experiments (Plackett-Burman design, steepest ascent design, and Box-Behnken design) were carried out to study the effects of culture medium components and fermentation conditions on the degradation of acetaldehyde by the strain. The growth curve and acetaldehyde degradation curve of the strain were established. [Results] A strain LT-2 with high acetaldehyde-degrading ability was obtained and identified as Bacillus velezensis LT-2. The optimum parameters for degrading acetaldehyde by B. velezensis LT-2 were fermentation in the medium composed of 30 g/L sucrose, 0.6 g/L nutrient broth, and 0.12 mol/L potassium chloride at 28 ℃, initial pH 7.5, inoculation size of 6%, and 200 r/min. Under the optimal conditions, B. velezensis LT-2 can grew in the medium with 1 g/L acetaldehyde and showed the 22 h acetaldehyde degradation rate of 89.77%±2.33%, which was 3.58 times of that before optimization. [Conclusion] B. velezensis LT-2 was effective in degrading acetaldehyde. This study provides experimental and practical references for the biological treatment of acetaldehyde-containing industrial wastewater.

Key words:acetaldehyde;biological degradation;optimization of fermentation parameters;bacillus velezensis