Microbial Inoculants and Their Impact on Soil Microbial Communities: A Review

Abstract

The knowledge of the survival of inoculated fungal and bacterial strains in field and the effects of their release on the indigenous microbial communities has been of great interest since the practical use of selected natural or genetically modified microorganisms has been developed. Soil inoculation or seed bacterization may lead to changes in the structure of the indigenous microbial communities, which is important with regard to the safety of introduction of microbes into the environment. Many reports indicate that application of microbial inoculants can influence, at least temporarily, the resident microbial communities. However, the major concern remains regarding how the impact on taxonomic groups can be related to effects on functional capabilities of the soil microbial communities. These changes could be the result of direct effects resulting from trophic competitions and antagonistic/synergic interactions with the resident microbial populations, or indirect effects mediated by enhanced root growth and exudation. Combination of inoculants will not necessarily produce an additive or synergic effect, but rather a competitive process. The extent of the inoculation impact on the subsequent crops in relation to the buffering capacity of the plant-soil-biota is still not well documented and should be the focus of future research.

The persistence and performance of phosphate-solubilizing Gluconacetobacter liquefaciens qzr14 in a cucumber soil

“…Some rhizosphere microbiome inoculations could modify bacterial communities and change plant flowering time (Panke-Buisse et al 2015). R. gallicum 8a3 and E. meliloti 4H41 inoculation showed significant effects on bacterial structure and diversity in the bulk soil of common bean (Trabelsi and Mhamdi 2013). In this study, we investigated the effect of G. liquefaciens qzr14 inoculation on bacterial community in rhizosphere and bulk soil simultaneously.…”

“…G. liquefaciens qzr14 inoculation had significant positive effects on bacterial diversity and biomass. Several reports indicated that the application of microbial inoculants can influence, at least temporarily, the resident microbial community's composition and function by directly inducing trophic competitions and antagonistic/ synergic interactions with resident microbial populations or indirectly mediating via enhanced root growth and exudation (Trabelsi and Mhamdi 2013). It was inferred that the introduced G. liquefaciens qzr14 effectively colonized the rhizosphere soil of cucumber and then expanded the rhizosphere bacterial communities by solubilizing soil phosphorus and supplying soluble phosphorus (Fig.…”

“…); (iv) improving soil structure; and (v) inducing systemic resistance (Bhattacharyya and Jha 2012;Bloemberg and Lugtenberg 2001). Apart from these features, PGPMs also promote plant growth by modifying the structure and function of microbial communities (Trabelsi and Mhamdi 2013). Recently, an increasing number of PGPMs being commercialized for various crops worldwide (Owen et al 2015).…”

The Role of Soil Beneficial Bacteria in Wheat Production: A Review

“…Inoculation with mixed different strains could be an alternative to inoculation with individual strains, likely reflecting the different mechanisms used by each strain in the consortium [173]. Combined inoculation with N 2 -fixing and phosphate solubilizing bacteria were more effective than a single microorganism for providing a more balanced nutrition for plants [19,174].…”

The Starter Effect of Non-Symbiotic Microbial Bioproducts on Wheat

“…Microorganisms in the rhizosphere play the role of intermediary between plants and soil, establishing complex interrelationships throughout the vegetation period and can perform functions such as soil improvement, degradation of pollutants and removal of dangerous compounds from ecosystem (Arora, 2015, Sandor et al, 2016. Rhizosphere control is a key process in mechanisms needed to solve critical issues facing the planet, including agriculture, improvement of water quality, climate change mitigation and biodiversity conservation (Trabelsi and Mhamdi, 2013).…”