一株新型Kerstersia gyiorum 菌株CY-2对 Cr(VI) 的还原性能

为探究李氏禾人工湿地-微生物燃料电池中铬还原菌与Cr(Ⅵ)的相互作用关系，从中筛选一株具有Cr(VI)还原能力的菌株CY-2，并对该菌还原Cr(VI)的特性和机制进行了探究。通过16S rRNA基因序列鉴定，该菌CY-2为Kerstersia gyiorum (OQ773627)，其对Cr(VI)的最低抑制浓度为300 mg·L⁻¹；在较宽的pH(4.0~9.0)、温度(27~52 ℃)和接种量(1%~20%)内还原Cr(VI)；并在pH=6.0、37 ℃和10%接种量下，该菌在36 h内对50 mg·L⁻¹ Cr(VI)的还原率为100%，对100、150、200和250 mg·L⁻¹ 的Cr(VI)在120 h内的还原率分别为62%、42%、25%和16%。此外，菌株CY-2对Mg²⁺、Mn²⁺、Cd²⁺、Cu²⁺、Co²⁺、Ni²⁺和Zn²⁺具有高耐受性，对呋喃唑酮、利福平和甲硝唑抗生素表现出耐药性，而对其他抗生素表现出敏感性。SEM-EDX和FTIR表征结果表明，菌株CY-2不对铬进行生物吸附；铬的存在导致了细菌细胞表面官能团的变化，并使含硫酸盐分子减少，从而该菌可能通过还原、生物累积和外排等机制有效还原铬。以上结果表明所筛选出的菌株CY-2在铬污染场地的有效生物修复中具有潜在的应用价值。

Reduction properties of Cr(VI) by a novel Kerstersia gyiorum strain CY-2

To investigate the interaction of chromium-reducing bacteria and Cr(VI) in the Leersia hexandra Swartz constructed wetlands-microbial fuel cells, we screened a strain, CY-2, with Cr(VI)-reducing ability and explored its characteristics and mechanism of Cr(VI) reduction. Based on 16S rRNA gene sequence analysis, we identified strain CY-2 as Kerstersia gyiorum (OQ773627), which had a minimum Cr(VI) inhibitory concentration of 300 mg·L−1. The strain CY-2 was capable of reducing Cr(VI) over a broad range of pH(4.0~9.0), temperature (27~52 ℃), and inoculum size (1%~20%). Under the conditions of pH=6.0, 37 ℃, and 10% inoculum, the strain exhibited a complete reduction rate of 100% toward 50 mg·L−1 Cr(VI) within 36 h, and the reduction rates of 62%, 42%, 25%, and 16% toward 100, 150, 200, and 250 mg·L−1 of Cr(VI), respectively, within 120 h. Additionally, strain CY-2 had a high tolerance to Mg2+, Mn2+, Cd2+, Cu2+, Co2+, Ni2+, and Zn2+, and displayed the resistance to the antibiotics furazolidone, rifampicin, and metronidazole, while was sensitive to other antibiotics. The SEM-EDX and FTIR characterization results indicated that the strain CY-2 did not perform bioremoval of chromium. However, the presence of chromium led to changes in the functional groups on the bacterial cell surface and reduced the amount of sulfate molecules. It is possible that the strain may effectively reduce chromium through mechanisms such as reduction, bioaccumulation, and efflux. These results suggest that the screened strain CY-2 has a potential application value in the effective bioremediation of chromium-polluted sites.