Plant growth‐promoting and biocontrol traits of endophytic <i>Bacillus licheniformis</i> against soft rot causing <i>Pythium myriotylum</i> in ginger plant
Khaloud Mohammed Alarjani, Mohamed S. Elshikh
Abstract
Abstract Bacterial endophytes from plants harbor diverse metabolites that play major roles in biocontrol and improve plant growth. In this study, a total of 12 endophytic bacteria were isolated from the ginger rhizome. The strain K3 was highly effective in preventing mycelia growth of Pythium myriotylum (78.5 ± 1.5% inhibition) in dual culture. The cell‐free extract (2.5%) of endophyte K3 inhibited 76.3 ± 4.8% mycelia growth, and 92.4 ± 4.2% inhibition was observed at a 5% sample concentration. The secondary metabolites produced by Bacillus licheniformis K3 showed maximum activity against Pseudomonas syringae (24 ± 1 mm zone of inhibition) and Xanthomonas campestris (28 ± 3 mm zone of inhibition). The strain K3 produced 28.3 ± 1.7 IU mL −1 protease, 28.3 ± 1.7 IU mL −1 cellulase, and 2.04 ± 0.13 IU mL −1 chitinase, respectively. The ginger rhizome treated with K3 in the greenhouse registered 53.8 ± 1.4% soft rot incidence, and the streptomycin‐treated pot registered 78.3 ± 1.7% disease incidence. The selected endophyte K3 improved ascorbate peroxidase (1.37 ± 0.009 µmole ASC min −1 mg −1 protein), catalase (8.7 ± 0.28 µmole min −1 mg −1 protein), and phenylalanine ammonia‐lyase (26.2 ± 0.99 Umg −1 ) in the greenhouse. In addition, K3 treatment in the field trial improved rhizome yield (730 ± 18.4 g) after 180 days ( p < 0.01). The shoot length was 46 ± 8.3 cm in K3‐treated plants, and it was about 31% higher than the control treatment ( p < 0.01). The lytic enzyme‐producing and growth‐promoting endophyte is useful in sustainable crop production through the management of biotic stress.