Development of a Biofertilizer from Plant Growth Promoting Rhizobacteria Isolated from Millipede Fecal Pellets

Abstract

Plant Growth Promoting Rhizobacteria (PGPR) are commonly used to produce biofertilizers. As such, the purpose of the present research was to develop a PGPR biofertilizer formulation from four Streptomyces strains isolated from millipede fecal pellets and to select suitable carriers for them. The four Streptomyces isolates were Streptomyces sp. KLS-AC04, S. zaomyceticus KLD-AC02-1, S. zaomyceticus KLD-AC16 and S. zaomyceticus KLD-AC30. Their compatibility was tested on Actinomycetes isolation agar by the cross-streak method and the results showed that the four isolates can coexist. A viability test was done with three different types of carriers: coconut coir, cow dung and peat moss. The best carrier for all isolates was peat moss (viability: 5.3 x 104 − 8.5 x 105 cfu/g). The isolate that exhibited the highest survival rate across the three carriers was Streptomyces sp. KLS-AC04. Seven PGPR biofertilizer formulations were developed, of which formulation 6 (cow dung: peat moss: KLS-AC04: KLD-AC02-1: KLD-AC16: KLD-AC30) showed the highest viability (6 x 105 cfu/g). The effects of the PGPR biofertilizer formulations on plant growth were explored on Chinese kale. This showed that the use of the four Streptomyces strains had a significant positive effect on germination percentage (range 47.5% − 80.0%), fresh weight (range 0.060 − 0.086 g), shoot length (range 36.1 − 60.4 mm), and root length (range 15.3 − 30.8 mm).