一株高效苯酚降解真菌的分离鉴定及其菌剂的制备

Isolation and identification of a high-efficiency phenol-degrading fungi and the preparation of its microbial inoculum

摘要:

【背景】含酚废水是普遍存在的有毒、难降解的有机污染物之一，生物法处理含酚废水因成本低、无二次污染而具有广阔的应用前景。可降解苯酚的微生物中，真菌比细菌对恶劣环境的适应性更好。针对液态菌液保存时间较短和运输困难的瓶颈，制备固体菌剂可以提高菌体存活率和储藏稳定性。【目的】筛选一株能够高效降解苯酚的真菌，优化其降酚性能并选择合适的载体制备菌剂。【方法】通过逐级驯化和纯化分离降酚菌，筛选得到降酚性能较强的真菌并通过ITS rDNA基因测序进行种属鉴定，通过参数优化进一步提高菌株降解苯酚的性能；以不同材料为载体制备菌剂，通过稀释平板计数法和苯酚降解实验探究菌剂在不同温度下的保存效果。【结果】分离筛选得到一株高效降解苯酚真菌QWD1，通过鉴定证明其属于Magnusiomyces capitatus，其最适降解条件：(NH4)2SO4为氮源，接种量为15%，pH为7.0，温度为35 °C，氮源浓度为14 mmol/L。在此条件下，28 d内对1 600 mg/L苯酚去除率可以达到97.15%；制备菌剂最合适载体为谷糠，适宜保存温度为4 °C，保存时间可达到90 d甚至更长，活菌数高达2.5×108 cfu/g左右，降解苯酚效果良好。【结论】筛选得到了一株高效降解苯酚真菌，优化其降解性能并将其制备成菌剂，为处理含酚废水提供了新菌种和理论支持。

Abstract:

[Background] Phenolic wastewater is toxic, widespread and difficult to be decomposed. Biological treatment of phenolic wastewater has a broad application prospects due to its low cost and no secondary pollution. In the microorganisms that can degrade phenol, the fungi are more adaptable to the harsh environment than the bacteria. For the bottlenecks such as the short storage time of the fungal suspension and the difficulties for transport, preparation of microbial inoculum can improve cell viability and storage stability. [Objective] This paper tried to isolate an efficient phenol-degrading fungi, optimize the degradation performance and select the appropriate carrier for the preparation of its microbial inoculum. [Methods] Step-by-step domestication and purification was used to isolate the efficient phenol-degrading fungi. The species identification was carried out by ITS rDNA gene sequence analysis. The phenol degradation performance was further optimized by single factor experiments. Four different materials was used as carriers for the preparation of the microbial inoculum, then investigation of its preservation effect at different temperatures by dilution-plate method and phenol degradation were tested. [Results] An efficient phenol-degrading fungi named QWD1 was isolated and the identification proved it belonged to the Magnusiomyces capitatus genus. The optimal degradation conditions were as follows: (NH4)2SO4 as nitrogen source, inoculum concentration 15%, pH 7.0, temperature 35 °C, nitrogen source concentration 14 mmol/L. Under this condition, the removal rate of phenol was up to 97.15% in 28 hours. The optimum carrier for the preparation of the fungi was cavings, the storage temperature was 4 °C and the storage time can reach 90 days or even longer. The number of viable fungi was about 2.5×108 cfu/g, and the effect of phenol-degrading was good. [Conclusion] A high-efficiency phenol-degrading fungi was screened, for which the degradation performance was optimized, and it was prepared as the microbial inoculum, which provided new strain and theoretical support for the treatment of phenolic wastewater.