Isolation, Characterisation and Biofertilizer Potential of Halo-Alkaliphilic Bacteria from Lonar Lake, Maharashtra
Author : Sonali Shrikant Patil, Gutte Jaywant Vaijanath and Bhosale Vishnu Suresh
Abstract :
Lonar Lake, Maharashtra, is a unique meteorite-impact soda lake characterised by extreme alkalinity, elevated salinity, and diverse extremophilic microbial populations. The present study aimed to isolate and characterise halo-alkaliphilic bacteria from Lonar Lake and evaluate their plant growth-promoting potential under alkaline soil conditions. Water samples collected from the lake were enriched in alkaline Yeast Extract Mannitol (YEM) broth and cultured on selective media including YEM agar, Pikovskaya’s agar, King’s B agar, and Magnesium Solubilizing Medium (MgSM). Morphological, microscopic, and biochemical characterisation of the isolates was performed using standard microbiological methods. The majority of isolates were Gram-positive, rod-shaped, endospore-forming bacteria showing optimal growth at pH 9, indicating strong alkaliphilic adaptation. Positive catalase, amylase, Simmons citrate, methyl red, and Voges–Proskauer reactions demonstrated broad metabolic versatility and potential plant growth-promoting rhizobacterial (PGPR) activity. Several isolates exhibited phosphate and magnesium solubilisation abilities on selective media.
The biofertilizer potential of the isolates was evaluated using a fenugreek (Trigonella foenum-graecum) plant growth bioassay under alkaline soil conditions (pH 8.5). Biofertilizer-treated plants showed significantly enhanced growth compared with untreated controls (p < 0.05). Root length increased from 7.5 ± 0.5 cm in controls to 11.5 ± 0.6 cm in treated plants, while shoot length increased from 12.4 ± 0.4 cm to 15.8 ± 0.5 cm. Leaf number also increased significantly in treated plants, accompanied by earlier germination, denser root systems, and darker green foliage. These findings demonstrate the strong plant growth-promoting potential of halo-alkaliphilic bacteria isolated from Lonar Lake and highlight their possible application as biofertilizer inoculants for saline and alkaline agricultural soils. The study further emphasizes the importance of extremophilic ecosystems as reservoirs of agriculturally valuable microorganisms for sustainable agriculture.
Keywords :
Halo-alkaliphilic bacteria, Lonar Lake, PGPR, Biofertilizer, Bacillus spp., Phosphate solubilisation.
