Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities

Abstract

"Interest in ecologically-based management of cacao diseases has lead to research on biocontrol. Sixty-nine endophytic Bacillus spp. were isolated from cacao trees escaping disease near Quevedo, Ecuador and screened as potential biological control agents. Four elite Bacillus spp. are currently being field evaluated to determine their ability to suppress witches' broom disease, caused by Moniliophthora perniciosa. Research was conducted to determine how applications of biocontrol agents impacts diversity and abundance of native microbial communities. Since most endophytes are likely neutral in terms of plant health, it is hypothesized that application of beneficial bacteria will displace neutral endophytes to positively impact overall plant health. Each isolate was applied to runoff at log 8.0 CFU/ml with 0.20% Silwet L-77 adjuvant to 4 branches each of 3 replicate nacional trees per treatment. Controls consisted of application of adjuvant alone. Three months after both the application and reapplication of the bacteria, leaf discs were excised from 2 sprayed leaves per branch. Leaf discs from one tree were combined and placed in RNALater for preservation during shipment. Genomic DNA was extracted from the sample and Automated Ribosomal Intergenic Spacer Analysis (ARISA) was utilized to determine ecological shifts in both bacterial and fungal communities. Data will be presented on effects of application of these biocontrol agents on native microbial communities." (Abstract from meeting website: http://www.apsnet.org/meetings/2009/abstracts/a09ma495.htm)