An in vitro antagonism test is a typical procedure for the selection of potential biocontrol strains. However,
the traditional method of screening antagonistic bacteria in vitro is a time consuming method when
conducting large-scale screening trials. In this study, an improved method for the selection of antagonistic
bacteria in vitro from compost was established based on the traditional method. 21 Antagonistic bacteria
out of 33 target strains isolated from vinegar waste compost using the improved method. The 16S
rDNA gene showed the 21 strains all belonged to the Bacillus genus and 18 different types of fingerprints
were obtained by enterobacterial repetitive inter-genic consensus (ERIC)-PCR. 18 Selected strains which
had the unique fingerprints all exhibited broad-spectrum antagonism towards the tested fungi and at
least two enzyme activities in vitro. Among them, majority of the isolates were siderophore producer,
some of them showed nitrogen-fixing ability and small of them were IAA producer. Four out of five
selected strains were found both to be effective in controlling wilt and damping-off disease and four
strains showed strong growth-promoting activities for cucumber seedlings under greenhouse conditions.
Thus, these results demonstrated that the improved method was an effective and rapid means to screen
potential antagonistic microorganisms in vitro. The results also showed that Bacillus sp. strains in vinegar
waste compost exhibited antibiosis against fungal pathogens and promoted the growth of cucumber
seedlings.