Background Inoculation of plants to enhance yield of crops and performance of other plants is a century old, proven technology for rhizobia and a newer venue for plant growth-promoting bacteria and other plant symbionts. The two main aspects dominating the success of inoculation are the effectiveness of the bacterial isolate and the proper application technology. Scope An assessment of practical aspects of bacterial inoculants for contemporary agriculture and environmental restoration is critically evaluated from the point of view of their current technological status, current applications, and future use. This is done because there are windows of opportunity for new developments in applied research using renewable, non-contaminated natural resources and new venues for research. Special emphasis is given to formulations and polymeric carriers. This review concentrates on practical aspect of inoculation technology dating from 1998 to 2013. Earlier publications are mentioned only for clarification of a specific point. Conclusions This review discusses characteristics of a carrier for inoculants, formulations of inoculants including liquid, organic, inorganic, polymeric, and encapsulated formulations. Technical aspects include inoculation techniques (soil and seed application), mass culture production, bulk sterilization, seed coating, shelf-life, and effect of moisture. Future research venues needed are noted.

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To understand bacterial community dynamics during the vermicomposting of lignin-rich coconut leaves using an indigenous isolate of an epigeic earthworm, Eudrilus sp., we employed amplicon-based pyrosequencing of the V1 to V3 region of the 16S rRNA genes. Total community DNA was isolated from two separate vermicomposting tanks in triplicate at four different stages of the process: pre-decomposition (15th day), initial vermicomposting (45th day), 50-70% vermicomposting (75th day) and mature vermicompost (105th day). Alpha diversity measurements revealed an increase in bacterial diversity till the 75th day, which then declined in the mature vermicompost. Beta diversity comparisons showed formation of distinct, stage-specific communities. In terms of relative abundance, the Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Nitrospirae, Planctomycetes, TM7 and WS3 groups increased until the 50-70% vermicomposting stage (p = 0.05). During the same time, the abundance of Bacteroidetes and Proteobacteria decreased. In contrast, the levels of Firmicutes increased throughout the 105-day vermicomposting process. The distribution of the most abundant OTUs revealed that each stage of the vermicomposting process possessed its own unique microbiome. Predictions based on the OTUs present by PICRUSt suggested a functional shift in the microbiome during vermicomposting. Enzymes and pathways of lipid and lignin metabolism were predicted to be initially abundant, but by the end of the process, biosynthesis of secondary metabolites and plant beneficial properties were enriched. The study revealed that bacterial communities undergo a continuous change throughout the vermicomposting process and that certain OTUs associated with specific stages could be targets for further improvements in the process.

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