Research On Iron Reduction With Bacterial Strains AMDY2-9-2 And AMDSY3-6-1 Isolated From Acid Mine Environment In Tongling, Anhui Province

The study on iron reduction and biological identification of two stains of iron-reducing bacteria isolated from acid mine environment in Tongling, Anhui province was carried out. Samples (acid mine drainage, tailings, sediments) collected from acid mine environment in Tongling, Anhui province were cultured by selective medium FeT and two strains of iron reducing microorganisms AMDY2-9-2 and AMDSY3-6-1 were obtained from FeT medium.16S rDNA amplified from bacterial genomic DNA was sequenced and analyzed, which showed that the closest strain of AMDY2-9-2 is Acidithiobacillus thiooxidans, with 99.79% sequence homology and the closest strain of AMDSY3-6-1 is Acidithiobacillus ferridurans, with 95.78% sequence homology.The features of strains AMDY2-9-2 and AMDSY3-6-1 on FeT medium can be described as follows:the colony size of both strains is about 0.05-0.1 mm, the colony is round, white, transparent and with entire edge. Two strains were gram negative and aerobic, the size (lengthxwidth) of two strains are about 0.5-1.0 μm×0.2-0.4 μm. Phenylalanine, hydrogen sulfide as the sources of energy can be used by AMDY2-9-2 and AMDSY3-6-1, and the use of urea is not very obvious, but glucose, lactose, maltose, mannitol, mannose, sucrose, arabinose, arabitol, D-ribose, xylose, xylitol, galactose, turanose, melezitose, sorbitol, sorbose, melibiose, cellobiose, glucosamine, ornithine, decarboxylase, fructose, inulin, methyl-D-glucopyranoside, DNA, tartrate, gluconate, acetate, galactitol, amygdalin, rhamnose, dextrine, starch, inositol, salicin, β-galactosidase, Propylene hydrochloride, simmons citrate, esculin, acetamide, nitrate, hippurate, N-acetyl glucosamine and sodium pyruvate can’t be used by AMDY2-9-2 and AMDSY3-6-1. Two strains do not exhibit ornithine decarboxylase, lysine decarboxylase, arginine decarboxylase activities. Two strains of bacteria can grow at pH values from 2.0 to 11.0, and the optimum pH value of strain AMDY2-9-2 is 5.0 and optimum pH value of strain AMDSY3-6-1 is 6.0. Optimum growth temperature of AMDY2-9-2 and AMDSY3-6-1 was both 30℃ and optimum salinity is 0%.Fe3+-reducing mechanisms of strain AMDY2-9-2 and AMDSY3-6-1 indicated that intact cells were required to reduce soluble Fe3+, while active enzymes, inactive cells and inactive enzymes can not reduce soluble Fe3+. Strain AMDY2-9-2 grew faster than strain AMDSY3-6-1 in different concentrations of Fe3+ in Fe medium. Two strains of bacteria showed very low reducing rate for structural Fe3+ in gossan. The detailed iron reduction mechanisms by iron-reducing bacteria need further research.