Abstract

The synthesis of poly(3-hydroxybutyric acid) (PHB) in nodule bacteria Rhizobium phaseoli grown in submerged culture was studied. The Law method for the determination of PHB was modified, which made it possible to isolate the polymer and to carry out its quantitative assessment directly in the biomass. Only S forms of R. phaseoli cells could synthesize PHB. Its accumulation was more active on carbon-rich medium (by ~50%), and the polymer granules were more clearly visible. The PHB synthesis increased with a decrease in aeration, and the maximum content was reached after 35−40 h of growth. The effect of the oxidative stress caused by t-butyl hydroperoxide and benzyl viologen on the growth of PHB-synthesizing bacteria was studied. Both compounds negatively affected bacterial growth. The growth was reactivated only in PHB-synthesizing S forms. We can conclude that PHB is a protector for nodule bacteria under the conditions of oxidative stress. The maximal PHB content in R. phaseoli cells reached 54% of the dry cell weight, which exceeded the values previously described for rhizobia. This value is close to those reported for the bacterial strains producing the polymer and used in biotechnology. We can conclude that rhizobia grown in the submerged culture can be potential producers of PHB and other polyhydroxyalkanoates.

中文翻译：

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栽培条件对根瘤菌根瘤菌合成聚3-羟基丁酸酯的影响

摘要

研究了在深层培养中生长的根瘤菌根瘤菌中聚（3-羟基丁酸）的合成。修改了测定PHB的Law方法，这使得分离聚合物和直接在生物质中进行定量评估成为可能。只有S形式的菜豆R细胞可以合成PHB。它在富碳培养基（约50％）上的积聚更为活跃，并且聚合物颗粒更清晰可见。PHB合成随着通气量的减少而增加，并且在生长35-40 h后达到最大含量。t引起的氧化应激的影响研究了过氧化氢丁基和苄基紫精对PHB合成细菌生长的影响。两种化合物均对细菌生长产生负面影响。仅以合成PHB的S形式重新激活生长。我们可以得出结论，PHB在氧化应激条件下是根瘤细菌的保护剂。菜豆中的最大PHB含量达到干细胞重量的54％，超过了先前针对根瘤菌所描述的值。该值接近于报道的生产聚合物的细菌菌株的值，并用于生物技术。我们可以得出结论，在水下培养物中生长的根瘤菌可能是PHB和其他聚羟基链烷酸酯的潜在生产者。