The present study is an attempt to understand the impact of bioinoculants, Azotobacter chroococcum (A), Bacillus megaterium (B), Pseudomonas fluorescens (P), on (a) soil and plant nutrient status, (b) total resident and active bacterial communities, and (c) genes and transcripts involved in nitrogen cycle, during cultivation of Cajanus cajan. In terms of available macro- and micro-nutrients, triple inoculation of the bioinoculants (ABP) competed well with chemical fertilizer (CF). Their 'non-target' effects were assessed in terms of the abundance and activity of the resident bacterial community by employing denaturing gradient gel electrophoresis (DGGE). The resident bacterial community (16S rRNA gene) was stable, while the active fraction (16S rRNA transcripts) was influenced (in terms of abundance) by the treatments. Quantification of the genes and transcripts involved in N cycle by qPCR revealed an increase in the transcripts of nifH in the soil treated with ABP over CF, with an enhancement of 3.36- and 1.57- fold at flowering and maturity stages of plant growth, respectively. The bioinoculants shaped the resident microflora towards a more beneficial community, which helped in increasing soil N turnover and hence, soil fertility as a whole.

中文翻译：

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生物接种剂在塑造根际微生物群落方面发挥着重要作用：对 Cajanus cajan 的实地研究

本研究试图了解生物接种剂、色球固氮菌 (A)、巨大芽孢杆菌 (B)、荧光假单胞菌 (P) 对 (a) 土壤和植物营养状况、(b) 总居民和活跃细菌群落的影响，和（c）在Cajanus cajan培养过程中参与氮循环的基因和转录本。在可用的宏量和微量营养素方面，生物接种剂 (ABP) 的三次接种与化肥 (CF) 竞争良好。通过采用变性梯度凝胶电泳 (DGGE)，根据常驻细菌群落的丰度和活性评估了它们的“非目标”效应。常驻细菌群落（16S rRNA 基因）是稳定的，而活性部分（16S rRNA 转录物）受处理影响（就丰度而言）。通过 qPCR 对 N 循环中涉及的基因和转录物的定量显示，与 CF 相比，用 ABP 处理的土壤中 nifH 的转录物增加，在植物生长的开花和成熟阶段分别增加了 3.36 倍和 1.57 倍。生物接种剂使常驻微生物群落形成一个更有益的群落，这有助于增加土壤氮的转化率，从而提高整个土壤的肥力。