Identification and quality control of BioGro inoculant biofertiliser strains

摘要

In the characterisation of potential biofertiliser inoculant strains for quality control and regulatory purposes, identification is the first step. Strains of BioGro inoculant biofertiliser developed at the Hanoi University of Science were identified at the University of Sydney using a number of different techniques, including morphological, biochemical and genetic methods. Subsequently, the identity of the strains was also confirmed at the laboratories of the German Culture Collection of Microbes (DSMZ), Braunschweig, Germany. The strains comprising BioGro 1 were identified as Pseudomonas fluorescens (1N), Citrobacter freundii (3C) and Klebsiella pneumoniae (4P), whereas BioGro 2 consisted of P. fluorescens (1N), Bacillus subtilis (B9), B. amyloliquefaciens (E19) and an as-yet-unidentified yeast (HY). Polyclonal rabbit antibodies were produced for all strains in Ho Chi Minh City, Vietnam, and further characterised for sensitivity and specificity to individual biofertiliser strains. The antibodies raised against C. freundii (3C) were subsequently used to optimise a colony immunoblotting protocol, which was demonstrated as a valid technique for the quantification of this strain in pure cultures and sand with low numbers of indigenous micro-organisms. The colony immunoblotting method described in this paper is ready to be used as a quality control tool at the inoculant laboratory and factory level, where mixed microbial cultures need to be monitored. Initial trials using aDNA colony blotting method also showed promise as a viable option for following population dynamics of inoculant biofertiliser strains in soil.