Viability of Pseudomonas plecoglossicida and Rhizobium sp. LM-5 as Liquid Bacterial Fertilizers in Various Formulated Carriers

Abstract

Microbial fertilizers, known as “biofertilizers,” have the ability to convert the nonusable to usable form into nutritionally important elements through biological processes. The effectiveness and viability of biofertilizer inoculants are correlated with carrier formulations. The purpose of this study was to evaluate the efficiency of various carrier materials for the shelf life of N-fixing P. plecoglossicida strain NBFPALD_RAS144 and Rhizobium sp. LM-5 to produce as liquid formulations. The experiments to investigate the effect of carrier formulation were conducted under laboratory conditions from January to July during 2015. The experiment was set up as a completely randomized design, consisting of nine different formulations each in three replications. The population of P. plecoglossicida strain NBFPALD_RAS144 and Rhizobium sp. LM-5 were enumerated at 2, 4, 8, 12, 16, 20, and 24 weeks of incubation at room temperature. The population of P. plecoglossicida strain NBFPALD_RAS144 after 24 weeks of incubation varied in different carrier formulations. Maximum cell density (12.8 × 10⁹ CFU mL⁻¹) was recorded in 5% molasses + 0.05% polyvinyl alcohol, while the lowest population (2.65 × 10⁹ CFU mL⁻¹) was recorded in 2.5% Triton. The population of Rhizobium sp. LM-5 remained relatively high even after 6 months of incubation in all the formulation of carriers under tested.