The Endophytic Bacteria Bacillus velezensis Lle-9, Isolated from Lilium leucanthum, Harbors Antifungal Activity and Plant Growth-Promoting Effects

Abstract

Bacillus velezensis is an important plant growth-promoting rhizobacterium with immense potential in agriculture development. In the present study, Bacillus velezensis Lle-9 was isolated from the bulbs of Lilium leucanthum. The isolated strain showed antifungal activities against plant pathogens like Botryosphaeria dothidea, Fusarium oxysporum, Botrytis cinerea and Fusarium fujikuroi. The highest percentage of growth inhibition i.e., 68.56±2.35% was observed against Fusarium oxysporum followed by 63.12 ± 2.83%, 61.67 ± 3.39% and 55.82 ± 2.76% against Botrytis cinerea, Botryosphaeria dothidea, and Fusarium fujikuroi, respectively. The ethyl acetate fraction revealed a number of bioactive compounds and several were identified as antimicrobial agents such as diketopiperazines, cyclo-peptides, linear peptides, latrunculin A, 5α-hydroxy-6-ketocholesterol, (R)-S-lactoylglutathione, triamterene, rubiadin, moxifloxacin, 9-hydroxy-5Z,7E,11Z,14Zeicosatetraenoic acid, D-erythro-C18-Sphingosine, citrinin, and 2arachidonoyllysophosphatidylcholine. The presence of these antimicrobial compounds in the bacterial culture might have contributed to the antifungal activities of the isolated B. velezensis Lle-9. The strain showed plant growth-promoting traits such as production of organic acids, ACC deaminase, indole-3-acetic acid (IAA), siderophores, and nitrogen fixation and phosphate solubilization. IAA production was accelerated with application of exogenous tryptophan concentrations in the medium. Further, the lily plants upon inoculation with Lle-9 exhibited improved vegetative growth, more flowering shoots and longer roots than control plants under greenhouse condition. The isolated B. velezensis strain Lle-9 possessed broad-spectrum antifungal activities and multiple plant growth-promoting traits and thus may play an important role in promoting sustainable agriculture. This strain could be developed and applied in field experiments in order to promote plant growth and control disease pathogens.

Antagonistic activity of glucanolytic bacteria Bacillus subtilis W3.15 against Fusarium oxysporum and its enzyme characterization

“…Rhizosphere bacteria B. subtilis is commonly studied for their strong antifungal activity against a wide range of phytopathogenic fungi such as Rhizoctonia solani, Alternaria alternata, F. oxysporum, Macrophomina phaseolina, and Pythium ultimum (Alamri et al 2012;Wu et al 2019 (Trinh et al 2019). Research by Khan et al (2020) revealed that the endophytic B. velezensis Lle-9 isolated from Lilium leucanthum had a plant growth-promoting effect and antifungal activity against Botrytis cinerea, Fusarium oxysporum, Fusarium fujikuroi, and Botryosphaeria dothidea.…”

“…Identification of the morphological characters of bacteria included colony-forming, growth pattern, and Gram-staining as previously described (Wikandari et al 2012;Khan et al 2020). The Gram-staining assay for bacterial cells and spores was performed as described previously (Moyes et al 2009).…”

Chemistry, Biosynthesis, Physicochemical and Biological Properties of Rubiadin: A Promising Natural Anthraquinone for New Drug Discovery and Development

“…presence of Rubiadin and other antimicrobial compounds in the bacterial culture can assist in isolating Bacillus velezensis Lle-9's antifungal activity. 64 Marioni et al 65 who investigated the antifungal effects of Rubiadin and RBME on Candida tropicalis confirmed that both compounds reduced biofilm formation and had an antifungal effect as mediated by oxidative and nitrosative stress under irradiation, with a significant increase in endogenous ROS and superoxide dismutase (SOD) activity. Rubiadin, in particular, altered the pro-oxidant-antioxidant balance.…”

“…The presence of Rubiadin and other antimicrobial compounds in the bacterial culture can assist in isolating Bacillus velezensis Lle-9’s antifungal activity. 64 …”

Antagonistic and Plant Growth-Promoting Effects of Bacillus velezensis BS1 Isolated from Rhizosphere Soil in a Pepper Field

“…Several antifungal compounds, including surfactins ( Grady et al, 2019 ), fengycins ( Adeniji et al, 2019 ), and bacillomycin D ( Luna-Bulbarela et al, 2018 ), exerting control over pathogenic fungi have been identified. B. velezensis is an endophytic species that lives in various parts of plants, mainly in the tissues of roots ( Chen et al, 2019 ), leaves ( Li et al, 2020 ), stems ( Kang et al, 2018 ), and even bulbs ( Khan et al, 2020 ). Many plant endophytes have been reported to protect the host against plant fungal pathogens and increase plant growth and tolerance to environmental stresses, making them suitable biocontrol agents ( Bandara et al, 2006 ; Cho et al, 2007 ; Li et al, 2016 ; Ullah et al, 2019 ).…”