两种方法形成菌丝球固定2-氯酚降解菌的对比

Comparison of two mycelial pellets formation methods to immobilize o-chlorophenol degradation bacteria

摘要:

[目的] 系统研究吸附法和同时培养法对所形成混合菌丝球的外观形态、内部结构及其去除2-氯酚效果的影响。[方法] 采用吸附法和同时培养法将可降解2-氯酚的光合细菌PSB-1D固定在黄孢原毛平革菌(Phanerochaete chrysosporium) DH-1发酵而成的菌丝球上,形成混合菌丝球。以单一菌丝球为对照,利用光学显微镜、扫描电镜等仪器观察混合菌丝球的外观形态和内部结构,考察2种方法对混合菌丝球成球效果的影响;以无菌培养液为空白对照,考察游离光合细菌、单一菌丝球、2种方法形成混合菌丝球对2-氯酚的降解效能。[结果] 在吸附法形成的混合菌丝球上,光合细菌主要集中在过渡区;而同时培养法将光合细菌牢固地包埋在菌丝球内核区,并大量簇状附着生长在菌丝交联的空隙处和每根菌丝上。在接种等量孢子和光合细菌的前提下,同时培养法较吸附法操作时间更短,成球数量更多,形成菌丝球干湿比更大,单位菌丝干重上固定的细菌数量更多。菌丝球降解体系和游离光合细菌对2-氯酚的降解均符合一级动力学特征。同时培养法形成的混合菌丝球降解效果最好,7 d内对初始浓度为50 mg/L的2-氯酚降解率可达89%以上,降解速率常数为0.3286 mg/(L·d),2-氯酚半衰期t_1/2为2.8 d。[结论] 首次报道黄孢原毛平革菌包埋固定化光合细菌形成混合菌丝球。该研究为生物质固定化材料的实际应用提供理论依据。

关键词:混合菌丝球;沼泽红假单胞菌;黄孢原毛平革菌;2-氯酚;生物质载体;生物降解

Abstract:

[Objective] To find an efficient and fast method for microbial immobilization, we compared simultaneity culture method and adsorption method on morphology and intrastructure of combined mycelial pellets, as well as their o-chlorophenol biodegradation efficiency. [Methods] The o-chlorophenol degrading photosynthetic bacterium PSB-1D was immobilized onto mycelial pellets formed by Phanerochaete chrysosporium DH-1 to form combined mycelial pellets. The morphology and intrastructure of pellets formed by two immobilization methods were observed by optical microscope and scanning electron microscope. Then, their differences were analyzed. Using the sterile medium as control, o-chlorophenol removal efficiency of free photosynthetic bacteria, single mycelial pellets and combined mycelial pellets formed by two methods were studied. [Results] Photosynthetic bacteria were largely concentrated in the core region of pellets formed by simultaneity culture method and grew in clusters on each mycelium and their intersections. As compared with simultaneity culture method, photosynthetic bacteria mainly grew in the transition region of pellets formed by adsorption method. With the same inoculation amount of spores and photosynthetic bacteria, the simultaneity culture method could immobilize more bacteria with little time. Moreover, average diameter, dry weight and dry wet ratio of pellets formed by simultaneity culture method were bigger than that by adsorption method, and their desorption amount were less. The o-chlorophenol degradation followed a first-order kinetics model. The combined mycelial pellets formed by simultaneity culture method could degrade above 89% of o-chlorophenol in medium with an initial concentration of 50 mg/L after incubation for 7 days. And the half-life periods (t_1/2) were shortened to 2.8 days. [Conclusion] The study provides the theoretical foundation for the practical application of the new biomass carrier to organic wastewater treatment.

Key words:combined mycelial pellet;Rhodopseudomonas palustris;Phanerochaete chrysosporium;o-chlorophenol;biomass carrier;biodegradation