Nanotube mediated cell-to-cell communication and cannibalism in Halobacillus sp. GSS1 isolated from Sundarbans, India: A cryptic story of survival under nutrient-limiting condition

Microorganisms play a self-protective role by evolving their genetic and metabolic machinery to thrive in extreme environmental habitats. Halophiles are such salt-loving extremophilic microorganisms able to adapt, survive, and tend to grow at high salt concentrations. In this study, we have isolated Halobacillus sp. GSS1 from Sundarbans mangrove, India having a strong salt-tolerant ability (up to 4M) in Zobell Marine 2216 medium. The salt adaptation mechanism of Halobacillus sp. was investigated by Confocal microscopy using [Na + ] specific dye, ‘Sodium Green’ indicating the ‘salt-in’ strategy for their osmoadaptation. Electron microscopic studies revealed that a contact-dependent cell-to-cell communication was profound among the Halobacillus sp. under nutrient limiting condition. This communication is mediated by ‘nanotube’, which is highly recommended for the exchange of molecular information between the two individual bacteria. The existence of the ‘ymdB’ gene strongly supports our claim for nanotube formation by Halobacillus sp. GSS1. Surprisingly, Halobacillus sp. not only utilizing the nanotubes for communication, rather they desperately use nanotubes as a survival weapon under nutrient limiting conditions by triggering cannibalism. This is the first-ever report on the existence of nanotube mediated cell-to-cell communication and cannibalism in any halophilic bacteria, isolated from Sundarbans mangrove forest, India. Highlights The existence of nanotube mediated cell-to-cell communication was discovered in Halobacillus sp. GSS1, isolated from Sundarbans mangrove, India. The communication of Halobacillus sp. GSS1 was established through single or multiple nanotubes with the neighboring cells. Intercellular nanotube communication was possible only after the participation of two individual bacteria. Halobacillus sp. GSS1 also uses these nanotubes as a survival weapon by triggering the cannibalism to kill their genetically identical siblings. The presence of the ymdB gene in Halobacillus sp. GSS1 strongly confers the evidence of nanotube formation. Graphical Abstract