~ 2558 ~ International Journal of Chemical Studies 2019; 7(3): 2558-2563 P-ISSN: 2349–8528 E-ISSN: 2321–4902 IJCS 2019; 7(3): 2558-2563 © 2019 IJCS Received: 25-03-2019 Accepted: 27-04-2019 Bharati Killadi Scientist, Division of Post- Harvest Management, ICAR- Central Institute for Subtropical Horticulture Rehmankhera, Po. Kakori, Lucknow, Uttar Pradesh, India Neelima Garg Principle Scientist, Division of Post-Harvest Management, ICAR- Central Institute for Subtropical Horticulture Rehmankhera, Po. Kakori, Lucknow, Uttar Pradesh, India Rekha Chaurasia Principle Scientist, Division of Post-Harvest Management, ICAR- Central Institute for Subtropical Horticulture Rehmankhera, Po. Kakori, Lucknow, Uttar Pradesh, India Correspondence Bharati Killadi Scientist, Division of Post- Harvest Management, ICAR- Central Institute for Subtropical Horticulture Rehmankhera, Po. Kakori, Lucknow, Uttar Pradesh, India Postharvest dip treatment of Bacillus subtilis for maintaining quality and shelf life of guava cv. Allahabad Safeda Bharati Killadi, Neelima Garg and Rekha Chaurasia Abstract In North India, guava fruits are harvested twice in a year yet maintaining the quality during storage is still a challenge due to its perishable nature. The use of chemicals for extending shelf life of guava should be avoided due to food safety concern since it is consumed along with skin. Recently bio-agents are being used as dip treatment for effective control of storage pathogens like Colletotrichum sp., Pestalotiopsis sp. and Lasiodiplodia sp. in fruits like apple, pear and strawberry. However, no such report is available for guava. In the present study Bacillus subtilis was used as bio-agent for enhancing the shelf life of guava. Guava fruits cv ‘Allhabad Safeda’ were subjected to post harvest dip treatments for 30 minutes with four strains of Bacillus subtilis viz. MTCC 7607, 7606, 7612, and 7605 @ 10 8 cells/ml dip solution and stored at 18 ±2 o C and 57±5 % R.H. The fruits were analyzed for physico-chemical parameters as well as microbial population at regular intervals. Among the treatments, fruits treated with Bacillus subtilis strain MTCC 7607 showed highest firmness after 10 days of storage. In general bio-agent treated fruits were glossy in appearance, better in quality and taste with uniform colour development and least disease incidence.Surface microbial analysis reflected the dominance of treated bacterial strain over other micro- organisms. Preliminary results indicate that Bacillus subtilis strain MTCC 7607 @ 10 8 cells/ml could act as a potent bio-agent for shelf-life extension of guava to control postharvest diseases. Keywords: Bio-agents, shelf-life, ascorbic acid, Bacillus subtilis, post-harvest Introduction Control of pathogens during post-harvest storage and handling has been a challenging task for which chemicals are generally used. Recently, bio-agents are considered as preferred tool to replace chemicals because of their safety on human health and the environment. There is a need to look for an effective bio-agent for control of post-harvest pathogens. Bio-agents actively produce antibiotics, whose action partially determines their effectiveness in controlling post harvest pathogens. Commercial products containing Bacillus subtilis (Serenade ad Rhio-plus) are being used for control of powdery mildew, late blight and brown rot on fruits Walton (2002) and Sharma (2009) [21] . The first report about B. subtilis affecting the physiological processes of postharvest of fruits is reduction in ethylene production in melons by Wang et al., (2010) [25] . Use of Bacillus subtilis as a biological antagonist has been reported from fruits such as apricot, avocado, cherry, citrus, litchi, strawberry, apple and pear Pussy and Wilson (1984) [16] , Demoz and Korsten (2006) [4] , Utkheda and Sholberg (1986) [23] , Sing and Daverall (1984) [22] , Jiang et al., (2001) [9] , Zhao et al., (2007) [26] Qi et al., (2005) [17] . Lise and Katze (1992) [11] and Lise and Jager (1995) [12] . The objective of the study was to evaluate strains of Bacillus subtilis as potential bio-agent for maintaining the quality of guava fruits under ambient conditions. Materials and methods B. subtilis strains of cow dung origin were obtained from culture collection of Microbiology laboratory in the Division of Post-Harvest Management, ICAR-Central Institute for Subtropical Horticulture, Lucknow. The bacterial culture was maintained on nutrient agar slants. Four bacteria isolated from cow dung were used namely Bacillus subtilis (MTCC 7605), Bacillus subtilis (MTCC 7606), Bacillus subtilis (MTCC 7607), Bacillus subtilis (MTCC 7612) from Microbial Type Culture Collection (MTCC) IMTECH, Chandigarh. The anti-pathogenicity was tested against Colletotrichum gloeosporioides, Botryodiplodia theobromae and Pestalotiapsidii as per standard protocol by dual culture technique (Anjaiah