~ 2062 ~ Journal of Entomology and Zoology Studies 2020; 8(3): 2062-2066 E-ISSN: 2320-7078 P-ISSN: 2349-6800 www.entomoljournal.com JEZS 2020; 8(3): 2062-2066 © 2020 JEZS Received: 29-03-2020 Accepted: 30-04-2020 Sirisha Tadigiri ICAR-Central Tuber Crops Research Institute, Sreekaryam, Thiruvananthapuram, Kerala, India Dhanya Das Department of Bioscience, Marthoma College, Thiruvalla, Kerala, India Allen RC Department of Bioscience, Marthoma College, Thiruvalla, Kerala, India Vishnu VR ICAR-Central Tuber Crops Research Institute, Sreekaryam, Thiruvananthapuram, Kerala, India Veena SS ICAR-Central Tuber Crops Research Institute, Sreekaryam, Thiruvananthapuram, Kerala, India Karthikeyan S ICAR-Central Tuber Crops Research Institute, Sreekaryam, Thiruvananthapuram, Kerala, India Corresponding Author: Sirisha Tadigiri ICAR-Central Tuber Crops Research Institute, Sreekaryam, Thiruvananthapuram, Kerala, India Isolation and characterization of chemical constituents from B. amyloliquefaciens and their nematicidal activity Sirisha Tadigiri, Dhanya Das, Allen RC, Vishnu VR, Veena SS and Karthikeyan S Abstract Secondary metabolites from cell free culture filtrate of B. amyloliquefaciens (Ba-14.5) showed strong nematicidal activity against root-knot nematode in preliminary tests. In the present study, chemical constituents present in secondary metabolites of B. amyloliquefaciens were investigated. Methanol fractions obtained from silica gel chromatography were analysed by using GC-MS. Thirteen compounds were revealed by GC-MS analysis and these constituents include stigmasta-3,5-dien-7-one (9.82%), Pregna-5, 16-dien-20-one, 3-(acetyloxy)-,(3.beta)-(5.12%), Benzeneacetaldehyde (3.96%), N-acetyl-3- methyl-1, 4-diazabicyclo[4.3.0]nonan-2,5-dione (3.65%), Pyrrolo (1,2-1) pyrazine-1,4-dione,hexahydro- (39.57%), 2,4,6,8-Tetramethyldecan-1-ol (0.54%), Pyrrolo (1,2-1) pyrazine-1,4-dione, hexahydro-3-(2- methylpropyl)- (4.96%), Hexadecanoic acid, methyl ester (0.35%), 5, 10-Diethoxy-2,3,7,8-tetrahydro- 1H, 6H-dipyrrolo(1,2-a (1.35%), n-Octadecanoic acid methyl ester (0.39%), 3,6-Disobutyl-2,5- Piperazinedione (4.21%), Hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester (9.7%), and Octadecanoic acid, 2,3-dihydroxypropyl ester (21.8%). Among thirteen compounds, three compounds like Benzeneacetaldehyde, 2-hydroxy-1-(hydroxymethyl) ethyl ester and Octadecanoic acid, 2,3- dihydroxypropyl ester possess nematicidal activity based on previous studies. Other compounds possess antimicrobial, antifungal, antioxidant, anticancer and insecticidal properties and are yet to be confirmed for their nematicidal activity. Our findings help to find potential compounds/metabolites from microbial source to develop nematicides for the management of root-knot nematode in horticultural crops. Keywords: B. amyloliquefaciens, culture filtrate, secondary metabolites, GC-MS, nematicidal activity 1. Introduction Plant parasitic nematodes are hidden enemies of crops and are recognised as one of the greatest threats to crops throughout the world [29] . Among the plant parasitic nematodes, root knot nematode is the major nematode causing damage to most of the economically important crops [24] . They are obligate parasites and have a wide host range including vegetables, cereals and fruit crops [1, 15] . It causes an estimated $118b annual losses to world crops [5] . Nematode infected plants exhibit symptoms like stunted growth, chlorosis, wilting and presence of galls on roots. The management of nematodes is more difficult than that of other pests because nematodes mostly inhabit the soil and usually attack the underground parts of the plants [44] . Although the application of chemical nematicides are effective but in long term usage and wide scale caused environmental pollution and enhancement of resistance in nematodes [16, 40] . Therefore, the search for novel, environmentally friendly alternative means instead of chemicals becomes emergency demand for management of root- knot nematodes [22, 49] . Nowadays, microorganisms and their metabolites have attracted the most attention as potential nematode biocontrol agents. Several antagonistic microbial strains such as Bacillus, Pasteuria and Pseudomonas have been developed into commercial formulations and are successfully used to control nematodes in agricultural fields [8, 19, 26, 33, 43] . Among bacterial bioagents, Bacillus spp. are dominant within the rhizosphere and are directly associated with plants and the soil environment, the inhibition of phytopathogens is a fundamental function of the bioactive molecules they produce [35, 47] . Number of investigations showed that nematode pathogenic bacteria like Bacillus kill nematodes by different mechanisms, including parasitism, antibiosis production of toxins, indirectly by interfering with the recognition of host plants inducing systemic resistance and by improving plant health [47] . They can synthesize various molecules that are toxic to nematodes [11, 36] . For example, B.