Isolation And Characterization Of A Iron-reducing Bacteria Strain

Dissimilatory iron reduction is the important link in the process of iron geoche mical cycle. It has received widespread attention because of it’s ability of fixing or degrading the heavy metals and non-biodegradable organic in the environment. Research on iron reducing bacteria separation and characteristics will help to furt-her understand the microbial reduction process of iron, enrich the pollution repair of biological materials, provide important theoretical basis for pollution repair app-lications. The purpose of this study was to isolate and purify effective iron-reducing bacteria from the sludge of wastewater treatment plant, study the ability of iron reducti-on in the different carbon source system and use different types of Fe(III), investigate the influence of electron shuttles on reduction process. In this research the metabolic degradation ability of trichloroethylene was also explored preliminarily. The main res-earch results were as follows:The isolated iron-reducing bacteria is short rod-shaped gram-negative bacteria, which grows best in the conditions of pH7,35℃ and the darkness.Best carbon concentration is 1.5mol/L in the process of dissimilatory iron reduction.Carbon source obviously affected the dehydrogenase activity, pH and H2 partial pressure on reduction process.The result of the dehydrogenase activity in carbon sources system was pyruvate>sucrose>glucose>acetate>lactate, the change of pH in the system was sucrose>glucose>pyruvate>lactate>acetate, sucrose, glucose and pyruvate as the electron donor can produce much more H2 than lactate and acetate.Among the four electron shuttles:riboflavin(VB2), vitaminB12(VB12), humic acid(FA) and anthraquinone 2,6-sulfonate(AQDS), VB2 and VB12 acted as electron donorcan, they were used as carbon source by reducing bacteria. FA and AQDS can be used as electron shuttle to promote Fe(OH)3 reduction obviously, increase the potential of reduction process, accelerate the Fe(Ⅲ) reduction rate.The isolated iron-reducing bacteria can’t use itself as carbon source to degradate TCE, But when sucrose as the metabolic substrate, the degradation rate was 40.1% at the optimal sucrose concentration 0.125mol/L. TCE degradation rate increased to 48.75% when added Fe(OH)3 in the co-metabolism system; TCE degradation rate can be further improved in the co-metabolism system when add Fe(OH)3 and FA at the same time.