Abstract
Black pod disease caused by the pathogenic fungus Phytophthora palmivora is a serious
threat to the cocoa industry causing the destruction of cocoa plants in many plantations
across Malaysia. The objectives of this study are to determine the antifungal activities
of the endophytic bacteria isolates and to identify the isolates. Four selected endophytic
bacteria previously isolated from tissues of healthy Theobroma cacao L. designated as
isolate LKM-UL, LKM-PA, LKM-PD, and LKM-BL were assessed for their abilities
to inhibit the growth of P. palmivora in vitro. Preliminary tests using dual culture
method showed that the isolate LKM-BL had the strongest inhibition towards the
growth of P. palmivora after 24 h of incubation compared to the other isolates. The
growth of LKM-UL, LKM-PA, LKM-PD, and LKM-BL revealed that the antifungal
activities against cocoa pathogen increases as the number of endophytic cells increases.
The cell-free supernatant from isolate LKM-BL produced the highest antifungal
activity against cocoa pathogen with an inhibition zone of 19.5 ± 0.50 mm during the
highest cell growth at 24 h of incubation. The endophytic bacteria were characterized
morphologically and based on biochemical tests. Based on the analysis of the 16S
ribosomal DNA sequences, isolate LKM-UL, LKM-PA, LKM-PD, and LKM-BL were
identified as Bacillus amyloliquefaciens, Pantoea agglomerans, Bacillus pumilus and
Bacillus subtilis respectively. The findings indicate that among the four endophytic
bacterial isolates studied, B. subtilis LKM-BL showed the highest antifungal activity
and has the potential to be used as a biological control agent towards the cocoa pathogen
P. palmivora.
Ishak Zubir, Eileen Rizlan, Ainon Hamzah, Wan Syaidatul . (2019) Endophytic bacteria from Theobroma cacao L. with antifungal activities against Phytophthora palmivora, Asian Journal of Agriculture and Biology, Volume 7, Issue 3.
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