Abstract: Sea sediments collected from Bohai were anaerobically enriched to obtain dissimilatory Fe(III)reducing bacteria. Characteristics of dissimilatory Fe(III) reduction by Fe(III)reducing bacteria were investigated under different electron acceptors. After fermentation for 12 h, the Fe(II) concentration of culture was (100.67±0.75) and (53.24±3.63) mg·L^-1 respectively, using ferric citrate and ferric hydroxide as electron acceptors. After 60 h, the Fe(II) concentration of culture was (118.95±1.47) and (119.74±3.96) mg·L^-1  respectively. The results indicated that soluble and insoluble electron acceptors could significantly affect Fe(III) reduction processes, but had no significant effect on the accumulation of Fe(II). Diversity of mixed culture and composition of dominant bacteria under different electron acceptors were analyzed by high throughput sequencing. Shannon diversity index of the bacterial community was 3.40 and 3.11 using ferric citrate and ferric hydroxide as electron acceptors, respectively, being higher than that of control group (with Shannon index 2.07). Such a result suggested that cultivation system with Fe(III) addition could significantly enhance the diversity of mixed culture. The dominant populations in the Fe(III)reducing bacteria were Clostridium_sensu_strictoand Romboutsia, belonging to Clostridiales, indicating that Clostridiales were the dominant bacteria in the mixed culture under Fe(III)reducing conditions.

Key words: Miami model, Thornthwaite Memorial model, climatic potential productivity, Yunnan Province.