Santos Sidnei C, Liebensteiner Martin G, van Gelder Antonie H, Dimitrov Mauricio R, Almeida Paulo F, Quintella Cristina M, Stams Alfons J M, Sánchez-Andrea Irene
Laboratory of Microbiology, Wageningen University.
Studies Institute in Health and Biological, Federal University of South and Southeast of Pará.
J Gen Appl Microbiol. 2018 Mar 27;64(1):1-8. doi: 10.2323/jgam.2017.02.009. Epub 2017 Nov 29.
Glycerol is a main co-product of biodiesel production. Crude glycerol may serve as a cheap and attractive substrate in biotechnological applications, e.g. for the production of valuable chemicals or as an electron donor for reduction processes. In this work, sulfate reduction with glycerol was studied at neutral and acidic pH using bioreactor sludge samples and Tinto River sediments as a source of inoculum, respectively. Communities of sulfate-reducing bacteria (SRB) and fermentative bacteria were co-enriched at both pH values. Molecular analyses revealed that sequences belonging to Desulfomicrobium genus were dominant in the cultures enriched at pH 7, while Desulfosporosinus sequences dominated in the culture enriched at pH 4. Glycerol conversion was coupled to sulfate reduction, but the substrate was incompletely oxidized to acetate in the neutrophilic enrichments, and acetate, lactate, and 1,3-propanediol under low pH conditions. Two strains belonging to Desulfomicrobium and Proteiniphilum genera were isolated from the neutrophilic enrichments, but the first isolate was not able to use glycerol, which suggests a syntrophic relationship between glycerol-degrading fermentative bacteria and SRB. A Clostridium strain able to grow with glycerol was isolated from the low pH enrichment. Our data indicate that glycerol promotes the growth of sulfate-reducing communities to form sulfide, which can be used to precipitate and recover heavy metals.
甘油是生物柴油生产的主要副产物。粗甘油在生物技术应用中可作为一种廉价且有吸引力的底物，例如用于生产有价值的化学品或作为还原过程的电子供体。在本研究中，分别使用生物反应器污泥样品和廷托河沉积物作为接种源，研究了在中性和酸性pH条件下甘油的硫酸盐还原作用。在这两个pH值条件下，硫酸盐还原菌（SRB）和发酵细菌群落都得到了共富集。分子分析表明，属于脱硫微菌属的序列在pH 7富集培养物中占主导地位，而脱硫孢菌属序列在pH 4富集培养物中占主导地位。甘油转化与硫酸盐还原相耦合，但在中性富集培养物中底物未完全氧化为乙酸盐，而在低pH条件下则氧化为乙酸盐、乳酸盐和1,3 - 丙二醇。从嗜中性富集培养物中分离出两株属于脱硫微菌属和嗜蛋白菌属的菌株，但第一株分离物不能利用甘油，这表明甘油降解发酵细菌与SRB之间存在共生关系。从低pH富集培养物中分离出一株能够利用甘油生长的梭菌菌株。我们的数据表明，甘油促进了硫酸盐还原菌群的生长以形成硫化物，可用于沉淀和回收重金属。
