Bacillus spp. AS A POTENTIAL BIOAGENT AGAINST MAJOR POSTHARVEST PATHOGENS OF KHASI MANDARIN, Citrus reticulata, Blanco
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Date
2023
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Abstract
Khasi Mandarin Citrus reticulata Blanco, which belongs to the Rutaceae family holds a significant importance as a horticultural crop and it occupied second most important fruit crops after banana. The present study aims to the identification of major postharvest pathogens of Khasi Mandarin (Citrus reticulata, Blanco) and evaluation of promising Bacillus spp. against major postharvest pathogens and assessment of bioagent-induced qualitative changes in citrus fruits. The isolated pathogen was identified as Penicillium sp. and Aspergillus sp. based on their cultural and morphological characteristics. Four Bacillus spp. were screened with both the pathogen and results showed that all the biocontrol agents were significantly inhibit the mycelial growth of the pathogens. B. subtilis LB22 were showed highest per cent mycelial growth inhibition of Penicillium sp. and Aspergillus sp. with 74.60% and 86.20%, respectively. SEM (Scanning Electron Microscopy) analysis of B. subtilis and pathogens interaction shows disintegration in fungal morphology. GC-MS analysis of B. subtilis LB22 found the presence of nine different antimicrobial compounds such as 2, 4-di-tert-butylphenol, n-hexadecanoic acid, 1H-Indene, 1-hexadecyl-2, 3-dihydro, etc. B subtilis cell suspension and cell free culture filtrate could significantly control the disease occurrence in Khasi Mandarin fruits with a 100% biocontrol efficiency, as compared with control and B. subtilis cell suspension, cell free culture filtrate with co-inoculation of pathogens. Peel and pulp were observed under SEM micrograph where colonization of Bacillus subtilis cells can be seen in the treated peel when compared with the untreated sample. The microphotograph of the pulp shows there is no bacterial colonization both in treated and untreated samples. The fruits treated with B. subtilis cell suspension show TSS of 11.90ºB and Titratable acidity of 0.85% as compared to the control after 15 days of storage which was non-significant. An Organoleptic test was carried out for untreated and treated samples concerning colour, flavour, texture, taste and overall acceptability.