Phosphorus (P), a primary macronutrient nutrient of soil, plays a vital role in plant nutrition and growth promotion. The objective of the present study was to explore potential phosphate solubilizing bacteria (PSB) from earthworms (Metaphire posthuma). A total of 8 PSB colonies were isolated from the gut content of earthworm using Pikovskaya’s agar media following the spread plate method. Out of eight isolates, one isolate (EGM8) of the gut of earthworm was selected as potential PSB using phosphate solubilization index and inorganic phosphate solubilizing activity. The isolate showing the highest phosphate solubilization index (4.8 ± 0.5) and inorganic phosphate solubilization activity (1.053 ± 0.18 mg/l) was selected for biochemical characterizations, plants (Vigna unguiculata, Amaranthus dubius, and Abelmoschus esculentus) seed germination, and growth studies. The EGM8 isolate showed a higher rate of seed germination (10–50%) and plant growth (shoot length — 21% and leaf number — 77%) properties compared to that of the control in A. esculentus. The EGM8 revealed higher plant growth due to producing the highest bioavailable P in the rhizosphere zone of plants. The selected PSB strain, EGM8, exhibited 99% similarity with Pseudomonas aeruginosa and hence identified as P. aeruginosa EGM8 strain. Summarily, it can be concluded that the P. aeruginosa EGM8 bacterial strain could be utilized as a potential biofertilizer for high crop production and may also be suggested that the earthworm would be a potential source for microbial biofertilizer.

Graphical abstract