Traits-Based Integration of Multi-Species Inoculants Facilitates Shifts of Indigenous Soil Bacterial Community

Abstract

Microbial co-inoculation is considered to be an innovative approach and had been applied worldwide. However, the underlying mechanisms of microbial co-inoculants constructions, especially the trait-based combination of distinctly different microbial species remains poorly understood. In this study, we constructed two microbial co-inoculants with the same three strains with emphasis on the microbial, soil and plant traits. Microbial co-inoculants 1 (M1) were constructed according to soil fertility, microbial activity and cucumber nutrient requirement with a 2:1:2 ratio (Ensifer sp. NYM3, Acinetobacter sp. P16 and Flavobacterium sp. KYM3), while microbial co-inoculants 2 (M2) were constructed according to soil fertility and cucumber nutrient requirement with a 1:10:1 ratio without considering the difference in the nutrient supply capability of microbial species. The results showed that M1 and M2 both obviously increased cucumber yields. The M1 had significant highest pH value, total nitrogen (TN) and invertase activity (IA). The M2 had significant highest available phosphate (AP), NO3-N, urea activity (UA), and alkaline phosphatase activity (APA). Gammaproteobacteria, Acidobacteria, Nitrospirae, and Armatimonadetes were significantly increased, while Actinobacteria and Firmicutes were significantly decreased by microbial co-inoculations (M1 and M2). The bacterial lineages enriched in M1 were Gammaproteobacteria and TM7. Acidobacteria, Bacteroidetes, and Deltaproteobacteria were enriched in M2. Principal coordinate analysis (PCoA) analysis showed that the bacterial communities were strongly separated by the different microbial inoculation treatments. The functional groups of intracellular_parasites were highest in M1. The functional groups of phototrophy, photoautotrophy, nitrification, fermentation, cyanobacteria, oxygenic_photoautotrophy, chitinolysis and animal_parasites_or_symbionts were highest in M2. Based on correlation analysis, it inferred that the M1 and M2 might promote cucumber yields by mediating bacterial community structure and function about nitrogen fixing and urea-N hydrolysis, respectively. Collectively, these results revealed that microbial co-inoculants had positive effects on cucumber yields. Trait-based integration of different microbial species had significant effects on soil properties and bacterial communities. It indicated that microbial activity should be considered in the construction of microbial co-inoculants. This will expand our knowledge in bacteria interaction, deepen understanding of microbial inoculants in improving plant performance, and will guide microbial fertilizer formulation and application in future.

Effects of growth‐promoting rhizobacteria on maize growth and rhizosphere microbial community under conservation tillage in Northeast China

“…In addition, PGPR inoculation in the present study obviously changed the structure of bacterial communities in the maize rhizosphere as detected using MiSeq high‐throughput sequencing technology (Figs 2 and 3; Table S6). Previous studies have reported that PGPR inoculation may regulate the composition of the host rhizobacterial communities (Zhang et al ., 2019b,c), and different inoculants have different effects on root‐associated bacterial communities, which may indirectly affect plant growth (Gadhave et al ., 2018; Wang et al ., 2018). In the current study, the abundance of certain bacterial populations in the maize rhizosphere was decreased or increased to various degrees after inoculation with the four PGPR strains (Fig.…”

“…For example, Wang et al . (2018) reported that inoculation with a mixture of Ensifer sp. NYM3, Acinetobacter sp.…”

“…Plant growth-promoting rhizobacteria (PGPR) can promote plant growth by providing nutrients, synthesizing phytohormones, defending against pathogens, reducing stress, alleviating soil contamination with heavy metals (Kloepper and Schroth, 1978; Bardi and Malus a, 2012;Cawoy et al, 2015;Wang et al, 2015) or improving the microbial community structure of the rhizosphere (Vessey, 2003;Malusa and Vassilev, 2014). For example, Wang et al (2018) reported that inoculation with a mixture of Ensifer sp. NYM3, Acinetobacter sp.…”

Response of Soil Bacterial Community and Pepper Plant Growth to Application of Bacillus thuringiensis KNU-07

“…Ke et al [39] reported that the inoculation of soil with Pseudomonas stutzeri A1501 significantly changed the indigenous soil bacterial community structure after 2 months of inoculation, and our findings are consistent with this report. Similarly, Wang et al [40] discussed the significant effect of bio-inoculants on soil microbial communities. In this study, the abundance of the Ellin 329 and Rhizobiales orders were higher in all samples.…”

Improvement of Phaseolus vulgaris growth by inoculation with multifunctional native rhizobacteria isolated from rhizospheric soils in Gaza strip- Palestine

“…In order to enhance the reliability and efficacy of microbial inoculants in agriculture and combining these PGPB by co-inoculation had been applied worldwide for more than a decade. As co-inoculation would mimic the natural situation more closely and allow the combination of various mechanisms without the need for genetic engineering [12].…”