Plant Growth-Promoting Features of Bacterial Endophytes isolated from Etlingera elatior

Etlingera elatior is a multifunctional plant that belongs to the family of Zingiberaceae, popularly known as torch ginger. It is used widely in culinary, medicinal, antibacterial agents, and ornamental purposes. The rhizome and root of torch ginger interact with a large number of microbes including the endophytic plant growth-promoting rhizobacteria (PGPR) in the rhizosphere. These bacterial endophytes involve directly or indirectly in the growth enhancement of E. elatior. This study aims to isolate the bacterial endophytes from the rhizome and root tissue of E. elatior and determine the plant growth-promoting activity of the isolated bacteria. The bacterial endophytes isolated from the rhizome and root tissue of E. elatior were characterized based on their morphological traits in vitro. Then the bacterial endophytes were screened for their plant growth-promoting behavior. This study found that most of the bacterial endophytes exhibit a positive result for plant growth-promoting activity. Interestingly, some of the isolates have the potential to produce Indole-3-acetic acid (IAA). IAA is a natural auxin hormone that is critical for the elongation and differentiation of plants roots. Other than that, the isolates also can solubilize the phosphate, thus making the phosphorus available to be uptake by plants. Moreover, the bacterial endophytes also produce ammonia and hydrogen cyanide (HCN). Ammonia indirectly improves the plant’s growth, while HCN helps to inhibit the development of plant diseases. Therefore, the bacterial endophytes isolated from the rhizome and root tissue of E. elatior have the promising potential to promote plant growth and protect the plant from disease