表面活性剂对热带假丝酵母降解苯酚的影响

通过液态发酵培养法探讨了添加2种化学表面活性剂十六烷基三甲基溴化铵(CTAB)、曲拉通X-100(Triton X-100)以及生物表面活性剂二鼠李糖脂(dirhamnolipid,diRL)对1株热带假丝酵母(Candida tropicalis)降解苯酚的影响.结果表明,发酵液中苯酚的分解和菌体生长的不同步,反映了苯酚对该菌的毒性作用以及苯酚降解过程中中间产物的形成.CTAB对热带假丝酵母具有毒性作用,抑制菌体对苯酚的降解.低浓度(0.1、0.3CMC)的Triton X-100对C.tropicalis的生长及对苯酚的降解有一定的促进作用,分别将苯酚降解完全的时间由空白的48h提前至24h和36h;随着Triton X-100浓度增大(1.0、3.0CMC),降解初期菌体的衰亡减缓,但使菌体生长滞后,苯酚分解完全的时间延长.生物表面活性剂diRL促进菌体对苯酚降解的同时显著地促进了C.tropicalis的生长,且促进作用随着加入diRL浓度的增大而增强,1.0、3.0CMC的diRL将苯酚降解完全的时间都提前到24h;而diRL在发酵过程中浓度也逐渐降低,这表明diRL很大程度上减弱了苯酚对菌体的毒性,并且可以共同作为碳源促进菌体的生长.

Effects of Surfactants on the Biodegradation of Phenol by Candida tropicalis

The method of liquid fermentation culture was used to study the influence of two synthetic surfactants, cetyl trimethylammonium bromide(CTAB) and Triton X-100, and a biosurfactant, dirhamnlipid(diRL), on phenol degradation by candida tropicalis CICC 1463. The results showed that at the beginning of degradation the yeast population decayed, phenol metabolization and bacterial growth did not occur simultaneously, which indicated the toxicity of phenol and formation of intermediate product. CTAB was toxic to c.tropicalis, and it restrained phenol removal. The phenol degradation was accelerated by Triton X-100 of low concentrations of 0.1 and 0.3 CMC, and the complete degradation was achieved at 24 h and 36 h, respectively, compared to 48 h of control. When Triton X-100 concentration was increased to 1.0 CMC or higher concentration, decay of yeast in the initial phase was weakened, but phenol removal and bacterial growth were lagged. The biosurfactant diRL enhanced phenol degradation and growth of the c. tropicalis markedly, and the effect increased with increasing of diRL concentration. Complete degradation was achieved at 24 h in the presence of 1.0 and 3.0 CMC diRL. The diRL concentration also decreased gradually during the fermentation. These results indicated that diRL could reduce phenol toxicity to a great extent and favor the bacterial growth as co-substrate.