Optimization of alginolytic conditions of Microcystis aeruginosa by bacteria EHB01 using response surface methodology

Abstract:

[Background] Cyanobacterial bloom caused by eutrophication has caused serious pollution to freshwater resources. The use of environmentally friendly alginolytic bacteria can effectively control the growth of cyanobacteria, which is one of the effective ways to prevent and control the formation of cyanobacteria bloom. [Objective] To optimize the alginolytic conditions of Microcystis aeruginosa by bacteria EHB01, so as to produce alginolytic agents for controlling the pollution of cyanobacterial bloom. [Methods] The concentration, temperature, light, C:N and N:P of alginolytic fermentation broth were analyzed by single factor test, and the carbon source, nitrogen source and pH of alginolytic bacteria EHB01 fermentation broth were optimized. Based on single factor test, the optimal quantity levels of key factors were determined by central composite design (CCD), and regression analysis was conducted by Desig-Expert 8.0.5. The parameters with the best alginolytic effect were obtained by response surface methodology (RSM). [Results] The effect of fermentation liquid concentration on the algicidal ratio was increasing continuously. The effect of temperature on the algicidal ratio was first increased and then decreased. However, the effects of light, C:N and N:P on the algicidal ratio of bacteria EHB01 fermentation broth showed a tendency of decreasing first and then increasing. The best carbon source for EHB01 fermentation liquid was sucrose, nitrogen source was potassium nitrate and pH was 7.5. Under the optimized conditions, the algicidal ratio was up to 86.97%, which was 21.72% higher than before optimization. [Conclusion] RSM was used to optimize the optimal culture conditions of alginolytic bacteria EHB01 fermentation broth, and the model fitting effect was good, which could provide an effective basis for industrial preparation of alginolytic agent.