Efficient Plant Growth-Promoting (PGP) Native Actinomycetes -Formulated Consortia Mode and Assessed Shelf Life Using Low-Cost Dynamic Media

Abstract

Various Actinomycete isolates were collected from the microbial germplasm, including Streptomyces rameus KAC3 (PP550146), Streptomyces bangladeshensis KAC4 (PP177363), Streptomyces mutabilis KAC6 (PP177364), Microbacterium arabinogalactanolyticum KAC8 (PP177365), Streptomyces calvus KAC10 (PP177366), Streptomyces werraensis KAC11(PP177366), and Streptomyces gancidicus KAC12 (PP177389). Three consortia formulations were then selected based on their compatibility with plant growth-promoting rhizobacteria (PGPR) properties under laboratory conditions: C1 consortium (KAC3, KAC10 and KAC11), C2 (KAC4, KAC8 and KAC10), and C3 (KAC11 and KAC12). In this study, we explored the use of locally available, cost-effective carrier materials, such as wood ash (NPK ratio: 1.72:0.86:3.6), charcoal (NPK ratio: 0.93:23.68:0.8), eggshell powder, a surfactant agent (SDS + CTAB), and vermi-compost (NPK ratio: 3.5:0.71:0.6). The CFU counts of Actinomycete isolates in the consortia were calculated over six months at different temperatures (28 and 35 ± 2o C) using these low-cost materials. The C1 consortium showed the highest stability in maintaining viable populations, whereas C2 and C3 showed the best performance in the combined-ingredient carrier material. The efficacy of C1 was monitored using an IoT device and further validated under different temperature conditions for six months. The data showed that temperature variation affected Actinomycete growth, with an optimal viability at 28 ± 2o C. Moreover, increases in temperature led to higher CO2 levels and decreased moisture and humidity, yet the Actinomycete population remained stable. This highly efficient C1 consortium formulation is a promising eco-friendly bioinoculant for sustainable agriculture.