Bacillus velezensis SK71 was isolated from the rhizosphere of a terrestrial orchid. The
result showed that SK71 has strongly inhibited Acidovorax avenae subsp. cattleyae. Isolate
SK71 produced a 22 mm inhibition zone against A. avenae subsp. cattleyae in paper disc
culture plate confrontation on nutrient yeast dextrose agar plates. The antagonistic bacterial
isolate was identified by using 16S rRNA sequence analysis. PCR detection of the sfp and ituA
genes coding for iturin A and surfactin, respectively, indicated a potential for the production of
these antibiotics. The production of hydrolytic enzyme and the plant growth–promotional
attribute of SK71 confirmed this multifaceted potential. The mixture formulation of SK71 with
diatomite powder as a carrier and carboxymethyl cellulose, K2HPO4 and glucose showed good
effect in suppressing the pathogen in vitro. Bulb treatment and spraying with these formulation
is an effective delivery system that can provide a conducive environment for B. velezensis SK71
to suppress brown spot disease on the terrestrial orchid. Greenhouse studies revealed that SK71
had a 53.34% efficacy in controlling brown spot disease. In this study, we consider that
formulation of SK71 is a promising natural biocontrol product, with scale–up possibilities for
health and growth promotion of terrestrial orchids.