固氮氧化亚铁钩端螺旋菌产次生矿物的条件优化及矿物鉴定

Condition optimization and identification of secondary minerals produced by Leptospirillum ferrodiazotrophum

摘要:

【背景】 固氮氧化亚铁钩端螺旋菌(Leptospirillum ferrodiazotrophum)培养过程中会产生大量次生矿物。【目的】 通过条件优化探究固氮氧化亚铁钩端螺旋菌产次生矿物的最优条件，为后续生物次生矿物的应用提供材料。【方法】 通过单因素试验探究pH、温度、转速、装液量对固氮氧化亚铁钩端螺旋菌次生矿物合成产量的影响，并根据试验结果设计响应面试验对产矿条件进行优化。对制备的次生矿物进行表征测试。【结果】 单因素试验结果表明，在pH 3.00、温度35.0 ℃、转速150 r/min条件下次生矿物的产量分别达到最高，装液量对次生矿物产量影响不显著。选取pH、温度、转速进行响应面试验得到产次生矿物最优条件为：pH 2.82、温度31.7 ℃，转速135 r/min。优化后生产率由单因素试验中最高值57.714 mg/(l·h)提高到65.436 mg/(l·h)。X射线衍射(X-ray diffraction, XRD)结果表明矿物结晶度较差，是一种无定形羟基高铁矿物，扫描电子显微镜(scanning electron microscope, SEM)结果表明矿物呈现表面片层短针状结构、具有较大的比表面积。【结论】 通过单因素试验和响应面试验优化了次生矿物的生物合成条件，为下一步次生矿物的应用打下了良好的基础。

Abstract:

[Background] Leptospirillum ferrodiazotrophum can produce a large amount of secondary minerals during the culture. [Objective] This study optimized the culture conditions of L. ferrodiazotrophum for secondary mineral production, aiming to provide materials for the subsequent application of biogenic secondary minerals. [Methods] Single factor tests were carried out to investigate the effects of pH, temperature, rotation speed and liquid loading on the production of secondary minerals by L. ferrodiazotrophum, on the basis of which the response surface method was employed to optimize the culture conditions. Subsequently, the produced secondary minerals were characterized and tested. [Results] The single factor tests showed that the secondary mineral yield reached the highest under the conditions of pH 3.00, 35.0 ℃, and rotation speed of 150 r/min, and the effect of liquid loading on the secondary mineral production was insignificant. The optimal conditions for producing secondary minerals were pH 2.82, 31.7 ℃, and rotation speed of 135 r/min. After the optimization, the yield increased from the highest value of 57.714 mg/(L·h) in the single factor tests to 65.436 mg/(L·h). X-ray diffraction results showed that the produced mineral had poor crystallinity and was an amorphous hydroxyl high-iron mineral. The mineral had a short needle-like structure and a large specific surface area. [Conclusion] This study optimized the biosynthesis conditions of secondary minerals through single factor tests and response surface design, laying a foundation for applying secondary minerals in the future.