Abstract

Medicinal plants serve as natural reservoirs for various types of beneficial microorganisms. Among these, endophytic bacteria act as a promising source of bioactive compounds with significant applications in multiple fields, including medicine, agriculture, and industry. This research aims to isolate and characterise endophytic bacteria inhabiting Acalypha indica L. and evaluate their potential in plant growth promotion and enzyme production. Based on 16S rRNA gene sequencing analysis, the seven morphologically distinct bacterial isolates exhibited close sequence similarity to Brucella anthropi, Priestia megaterium, Staphylococcus epidermidis, Microbacterium paludicola, Agrobacterium tumefaciens, Enterobacter cloacae, and Nocardioides zeae. Among these, B. anthropi demonstrated superior plant growth-promoting potential, as evidenced by its higher production of indole-3-acetic acid and ability to enhance the growth of Vigna radiata seedlings. Priestia megaterium exhibited notable potassium-solubilising activity, whereas S. epidermidis showed efficient phosphate solubilization. All seven isolates showed aminocyclopropane-1-carboxylic acid deaminase activity and ammonia production, indicating their collective potential in plant growth promotion. Enzymatic profiling revealed that S. epidermidis exhibited lipase activity, while E. cloacae demonstrated cellulase and amylase production. Although the isolation of endophytic bacteria is well documented, the specific functional attributes of these isolates from this host plant have not been previously reported. Therefore, this study provides a foundational screening of promising endophytic bacteria with potential applications in sustainable agriculture and biotechnology.

Key words: Endophytic bacteria, plant growth promotion, confocal microscopy, Acalypha indica