Journal Journal of Applied Horticulture, 14(2): 102-109, 2012 Appl Postharvest microbial diversity on major cultivars of Indian mangoes S.N. Jha*, Pranita Jaiswal, K. Narsaiah, Rishi Bhardwaj, Poonam Preet Kaur, Ashish Kumar Singh, Rajiv Sharma and R. Kumar Agricultural Structures and Environmental Control Division, Central Institute of Postharvest Engineering & Technology, Ludhiana 141004, India. *E-mail: snjha_ciphet@yahoo.co.in Abstract Microbial diversity on fruit surface of nine mango cultivars (Alphonso, Banganapalli, Chausa, Dashehri, Kesar, Langra, Mallika, Maldah and Neelam) harvested from orchards of nine Indian states (Andhra Pradesh, Bihar, Gujarat, Karnataka, Maharashtra, Orissa, Punjab, Tamil Nadu and Uttar Pradesh) were studied using standard methods. A total of 47 fungal and 123 bacterial isolates were purified from 761 mango samples, which included 63 Gram positive and 60 Gram negative bacterial isolates. The relative abundance of Gram positive, Gram negative bacteria and different filamentous fungi varied among cultivars. Gram positive bacteria dominated on Langra of Uttar Pradesh, while Dashehri from Punjab showed dominance of Gram negative bacteria. Among total fungal isolates, the common genera were Aspergillus and Fusarium, while among bacterial isolates, the most common genera were Bacillus, Aeromonas, Pseudomonas, Lactobacillus, Citrobacter, Mycobacterium and Serratia. Alphonso and Kesar variety from Maharashtra showed maximum and minimum fungal diversity, respectively. Genera and species identified include members known for spoilage of fruits; having all types of pectinase and cellulase activities and those used in biocontrol of plant pathogens. Key words: Bacteria, biochemical, diversity, filamentous fungi, mango, relative abundance Mango (Mangifera indica) is an important tropical fruit and India is the largest mango producer contributing 37% of 30.5 million tons of total global mango production. Annually, India supplies 50,000 tons of mangoes to different parts of the world including Japan, Middle East, Europe and United States and the demand is increasing year by year (Pandit et al., 2009). However, tropical and subtropical fruits such as mango present greater problems in transportation and storage due to its perishable nature and presence of numerous microflora on its surface (Mitra and Baldwin, 1997) which may cause spoilage of fruits. The postharvest loss of such perishable commodities is estimated to be as high as 50% (Mitra and Baldwin, 1997). This can partly be reduced by knowing the spectrum of microbial community and devising the measures to reduce their effect. Microorganisms associated with postharvest spoilage of fruits have drawn attention of scientists for years (Verma et al., 1991; Okigbo, 2001). Mango fruit is also susceptible to many postharvest diseases such as anthracnose (Colletotrichum gloeosporoides) and stem end rot (Lasiodiplodia theobromae) during storage under ambient conditions or even at low temperature (Arauz, 2000). Spoilage microbes are capable of colonizing and creating lesions on healthy, undamaged plant tissue (Tournas, 2005). Many spoilage microorganisms use their extra cellular lytic enzymes to degrade plant polymers into simpler fractions which can be used as nutrients for their growth. Fungi and many bacterial strains produce an abundance of extracellular pectinases and hemicellulases, which play a major role in spoilage (Miedes and Lorences, 2004). Besides, many microbes isolated from the fruit surface have been identified to be useful agents in postharvest treatment (Wisniewski and Wilson, 1992; Wilson et al., 1993). Extensive studies have been conducted on the diversity of epiphytic microbes on annuals bearing deciduous leaves (De Jager et al., 2001; Joshi, 2008). Recently microbial population on long living leaves of evergreen trees like mangoes have also been studied (Pruvost and Luisetti, 1991; De Jager et al., 2001; Ngarmsak et al., 2006). Information on microbial diversity on Indian varieties of mangoes is missing, thererefore the objective of this investigation was to study the microbial diversity on the surface of mango fruit for deciding strategies to reduce postharvest spoilage of commercially important varieties. Materials and methods Complementary Copy Introduction Sampling procedure: Major mango cultivars (Alphonso, Banganapalli, Chausa, Dashehri, Kesar, Langra, Maldah, Mallika and Neelam) were collected from orchards of nine Indian states (Andhra Pradesh, Bihar, Gujarat, Karnataka, Maharashtra, Orissa, Punjab, Tamil Nadu and Uttar Pradesh) using complete randomized block design (Jha et al., 2010). Fruits with 5-10 cm stalk were manually plucked directly in pre-sterilized zip locked plastic bags in the forenoon, from each side and also from centre of tree canopy in random manner. Sampling schedule along with abbreviations used for each cultivar is presented in Table 1. Zip locked plastic bags were transported to the laboratory in the well ventilated corrugated fiber board boxes along with partially refrigerated gel packs placed in between the two layers of mangoes to minimize the quality loss (Jha et al., 2010). Isolation and growth of bacterial and fungal isolates: Microbial communities from the mango fruit were isolated by washing and dilution plating method (Jha et al., 2010). In order to isolate total microbial diversity from mango surface, three Postharvest microbial diversity on major cultivars of Indian mangoes mangoes from each cultivars were used in experimentation. The mangoes were washed and suitable dilutions of wash water were prepared. Inoculums from different dilutions containing surface micro flora from mango were plated on Nutrient Agar (NA) and Potatao Dextrose Agar (PDA, Himedia, India) plates in triplicate (Atlas and Snyder, 2006). NA plates were incubated at 37oC and PDA plates at 28oC. After incubation, the individual colonies were picked up and purified with streak plate method. The isolates were grown on their respective media in petriplates or slants to study their morphological features. Bacterial isolates were characterized based on shape, color, surface and edge of the bacterial colonies while filamentous fungi were characterized based on their hyphal and spore characteristics according to Hawksworth et al. (1995). Identification of filamentous fungi was further confirmed at NTCC (National Type Culture Collection Center), Indian Agricultural Research Institute, New Delhi based on morphological features. Biochemical characteristics: Each bacterial isolate was propagated in nutrient broth before use and an overnight culture was employed in the tests. Standard staining procedures (such as Gram’s staining, Negative staining, Acid fast staining, Spore staining) and biochemical tests namely citrate, urease, hydrogen sulfide production, carbohydrate utilization test, lactose fermentation test, glucose oxidation and fermentation test, indole production test, methyl red test, oxidase test, catalase test, flouroscein production test, cellulose degradation test and pectin hydrolysis test were used for characterization of microbial isolates using commercially available media (Himedia, India). The isolated organisms were purified and assayed as recommended in Bergey’s manual (Holt et al., 1994). Statistical analysis: Evenness/Relative abundance (RA): Evenness is defined as a measure of the relative abundance of different species which was calculated as below: RA (%) = (N x 100) /T Where, N = Total number of isolates belonging to one group T = Total number of isolates belonging to all groups Richness was calculated as number of species per sample. Simpson’s Index (D) was calculated as below: D = ∑ (n/N)2 Where, n = Total no. of organisms of a particular species N = Total no. of organisms of all species Simpson’s Index of Diversity Simpson’s index of diversity = 1 – D Where, D = Simpson’s index Results and discussion Bacterial diversity: Microbial diversity describes complexity and variability at different levels in an ecosystem where, microbes play a crucial role in biological organization. Special interest in the fruit surface microorganisms exist in view of identifying microbes responsible for spoilage of mango fruit and further development of biosensor by generating antibodies against them for quick identification. Further, microbes present on plant surface have been reported to fix atmospheric nitrogen, compete with plant parasites, produce plant growth regulator such as gibberellic acid and produce lipases which degrade surface waxes (Chun and Mc Donald, 1987). If such organism also resides on fruit, they may predispose fruit to moisture loss and decay during long term storage. In current scenario, the adverse effects of synthetic chemical residues on human health and the environment have lead scientists from all over the world to develop alternative control strategies such as studies on natural microbial diversity on fruit surface and their role in plant protection. A total of 123 bacterial strains were isolated from the mango fruit samples of nine major cultivars collected from nine Indian states. All the isolates were characterized initially based on the biochemical nature of cell wall using standard Gram staining procedure. Results indicated that among total 123 isolates, Gram positive and Gram negative bacterial isolates were found to be 51.22 and 48.78%, respectively. The RA of Gram positive bacteria varied from 11.11% in CU to 75.00 % in LU (Table 2), while that of Gram negative bacteria varied from 25.00 % in LU to a maximum of 100.00 % in DP. In variety BA and NT, the RA of Gram positive and Gram negative was found to be almost same. Results showed great variation in RA of Gram positive and Gram negative bacteria among different mango cultivars (except BA, MO and NT) which might be attributed to variation in environmental condition (humidity) at the time of sampling at different sampling site. Silva et al. (2000) also reported that the percent composition of Gram positive and Gram negative bacteria is mainly governed by moisture content of the atmosphere, with Gram positive bacteria dominated in wet and Gram negative bacteria in dry atmosphere. The percentage of rods was found to be twice that of cocci in both Gram positive and Gram negative bacteria in all the mango cultivars indicating the dominance of spoilage causing microflora, as most of the bacterial strains responsible for spoilage of fruits and vegetables are reported to be Gram positive or Gram negative rods (Frazier and Westhoff, 2008). Complementary Copy Table 1. Abbreviations used for mango cultivars harvested from different locations Name of cultivar Place of procurement Abbreviations used Alphonso Karnataka AK Alphonso Maharashtra AM Banganapalli Andhra Pradesh BA Banganapalli Orissa BO Chausa Punjab CP Chausa Uttar Pradesh CU Dashehri Punjab DP Dashehri Uttar Pradesh DU Kesar Gujarat KG Kesar Maharashtra KM Langra Uttar Pradesh LU Maldha Bihar MB Mallika Orissa MO Neelam Tamil Nadu NT 103 Among total bacterial isolates, the colonies of 55 isolates were found to be pigmented (Table 3). Such chromogenic isolates potentially have selective advantage over other inhabitants because their pigmentation protects them from ultra violet radiation and are frequently isolated and had been reported to colonize plant surface in large numbers (Crosse, 1971; Hirano and Upper, 1991; Mansvelt and Hattingh, 1987). Biochemical characterization of all the 123 bacterial isolates showed presence of 63 Gram positive and 60 Gram negative isolates (Table 3). Among Gram positive isolates, 40 were found to be rod shaped and the rest 23 were cocci form. Further, among 104 Postharvest microbial diversity on major cultivars of Indian mangoes Table 2. Number and Relative abundance of Gram positive and Gram negative bacteria from different mango cultivars AK AM BA BO CP CU DP DU KG KM LU MB MO NT Gram positive Gram positive Gram negative Gram negative Gram positive Gram positive Gram negative Gram negative (number) (RA) (number) (RA) rods (RA) cocci (RA) rods (RA) cocci (RA) 9 13 5 4 4 1 0 1 6 5 3 1 4 7 52.94 72.22 50.00 57.14 66.67 11.11 0.00 25.00 60.00 62.50 75.00 16.67 44.44 50.00 8 5 5 3 2 8 1 3 4 3 1 5 5 7 47.06 27.78 50.00 42.86 33.33 88.89 100.00 75.00 40.00 37.50 25.00 83.33 55.56 50.00 Gram positive rods, 14 isolates were found to form spores and 26 were non-spore formers. These spore forming strains were purified under purely aerobic conditions, therefore, the isolates identified belonged to genera Bacillus. Among the 26 non-spore formers, 10 showed positive acid fast reaction, which may be from genus Mycobacterium and remaining 16 showed the negative acid fast reaction. Further, results of catalase test showed that all the 16 bacterial isolates with negative acid fast reaction belonged to Lactobacillus genus, out of which 13 bacterial isolates showed acid formation on glucose fermentation test, which gave indication that these isolates may be L. casei or L. delbrueckii and remaining 3 bacterial isolates gave no reaction, indicating that they belong to other species of Lactobacillus genera. Bacillus spp. as a group is one of the important components of soil microbial community (Prescott et al., 2006). Many Bacillus spp. had been reported to secrete wide range of degradative enzymes such as cellulases, amylases, pectinases and proteases (Silva et al., 2000). Both pectinase and pectate lyase had been reported from Bacillus spp. (Soriano et al., 2000). In current investigation many identified isolates as Bacillus (according to Bergey’s manual) have shown presence of hydrolytic enzymes cellulases and pectinases, which might endow them with the advantage of colonizing the fruit surface. De Jager et al. (2001) also reported the predominance of Bacillus pumilis on mango leaf surface besides other bacterial genera (Cornyform, Pseudomonas, Xanthomonas and Erwinia) found to be present on mango phylloplane. All 23 isolated Gram positive cocci showed negative catalase activity indicating that they may either belong to Streptococcus or Enterococcus genus (Table 3). Among 60 Gram negative bacterial isolates, 37 were rod shape and rest were cocci. Among Gram negative rods 26 isolates showed positive oxidase test, and other 11 showed negative oxidase test. The isolates showing negative oxidase test belonged to family Enterobacteriaceae. Out of 26 isolates with positive oxidase test, 24 exhibited acid production on glucose fermentation, further, they didn’t require presence of sodium in the medium for growth. Therefore, isolates represent characteristics of genus Aeromonas as given in Bergey’s manual and rest of bacterial strains (2), although were able to ferment glucose, didn’t produce acid in the medium. Thereby, indicating that these isolates can belong to genus Pseudomonas. Among the Gram negative bacterial isolates, Aeromonas was found to 35.29 38.89 40.00 42.86 50.00 0.00 0.00 25.00 30.00 62.50 50.00 0.00 11.11 35.71 17.65 33.33 10.00 14.29 16.67 11.11 0.00 0.00 30.00 0.00 25.00 16.67 33.33 14.29 29.41 22.22 30.00 28.57 16.67 44.44 100.00 50.00 20.00 37.50 25.00 50.00 33.33 28.57 17.65 5.56 20.00 14.29 16.67 44.44 0.00 25.00 20.00 0.00 0.00 33.33 22.22 21.43 be the most dominant genera as it has been isolated from 12 mango cultivars (AK10, AK11, AK17, AM04, AM06, AM07, AM12, BA05, BA09, BA10, BO03, CP06, CU01, CU02, CU07, DU03, KG09, KM03, KM08, MB02, MB06, LU03, NT07 and NT10), while Pseudomonas was found on BO02, MO07 and NT05 cultivars. Aeromonas is widely found in nature including decomposing vegetable matter, while Pseudomonas is well known for their ability to metabolize a variety of diverse nutrients (Frazier and Westhoff, 2008). Many strains have been reported to play an important role in environmental biotechnological applications (Walsh et al., 2001; Mark et al., 2006; Ali Khan and Ahmad, 2006). However, on the contrary, many other have been reported to be phytopathogen and are widely dispersed on plants mainly on leaves and rhizosphere (Silva et al., 2000). Bacterial isolates belonging to Enterobacteriaceae family were further sub grouped based on the lactose fermentation test and results indicated that 7 (MB03, DU02, MO08, CU08, KG01, MO09 and NT01) were able to ferment lactose (Table 3). Further MB03 showed indole production by oxidizing an essential amino acid tryptophan, which utilized citrate as sole carbon source and showed negative VP test which is characteristic of genus Citrobacter. DU02 and MO08 were able to ferment lactose, showed indole production but did not show citrate reaction, which is characteristic of genus Escherichia. CU08, KG01, MO09 and NT01 did not oxidize tryptophan but KG01 showed positive reaction for both MRVP tests indicating that KG01 may be Enterobacter intermedius. CU08 & MO09 showed positive test for methyl red only and NT01 showed positive VP test only indicating that CU08 and MO09 may be Serratia fonticola / Klebsiella pneumoniae (subsp. Ozaenae) / Citrobacter freundii and NT01 may be Klebsiella pneumoniae (subsp. pneumoniae)/ Enterobacter spp. / Erwinia caotovora / Serratia rubidaea. The other four isolates of Enterobacteriaceae family showing negative reaction for lactose fermentation were able to oxidize tryptophan to indole and showed negative result for hydrogen sulfide production test, may belong to genus Morgenella /Providencia. Enterobacter is a common inhabitant of soil and sewage. Erwinia spp. is another common Gram negative spoilage microbe associated with fresh-cut vegetables. Erwinia, a genus within the family Enterobacteriaceae are small rods and facultative anaerobes. Erwinia is reported to cause rapid necrosis, progressive tissue maceration called “soft-rot”, occlusion of vessel elements called “vascular wilt,” and hypertrophy leading to gall or tumor formation in plant tissues (Margaret et al., 2009). Brocklehurst et al. (1987) and Manvell and Ackland (1986) identified E. carotovora as Complementary Copy Cultivar Table 3. Morphological and biochemical characteristics of bacterial isolates from nine different mango cultivars Morphological characteristic Biochemical characteristics Isolate Group G N S A P T S 1 2 3 4 5 6 7 8 9 10 11 AK1 A + R + + + + + + AK2 A + R + + + + + + + + AK3 A + R + + + + + AK4 A + R + + + + + + + + + + AK5 A + R + + + + + + AK6 B + C + + + + + + + + + + AK7 B + C + + + + + + + + AK8 B + C + + + + + + + + AK9 A + R + + + + + + + + + AK10 C R + + + + + + + AK11 C R + + + + + + + + + + AK12 C R + + + + + + + + + AK13 D C + + + + + + AK14 D C + + + + + + + + AK15 D C + + + + + + + AK16 C R + + + + + + + + + AK17 C R + + + + + + + + + AM1 B + C + + + + + + AM2 A + R + + + + + AM3 B + C + + + + + + + + AM4 C R + + + + + + + AM5 B + C + + + + + + AM6 C R + + + + + + + + AM7 C R + + + + + + + + AM8 B + C + + + + + + AM9 A + R + + + + + + AM10 A + R + + + + AM11 A + R + + + + + + AM12 C R + + + + + + AM13 A + R + + + + + + AM14 A + C + + + + + + AM15 A + C + + + + + AM16 D C + + + + + + AM17 A + R + + + + + + AM18 A + R + + + + + + + BA1 A + R + + + + + + + + + BA2 B + C + + + + + + BA3 D C + + + + + + BA4 A + R + + + + + BA5 C R + + + + + + + BA6 D C + + + + + + + BA7 A + R + + + + + + BA8 A + R + + + + + + + + BA9 C R + + + + + + + + + + BA10 C R + + + + + + + BO1 D C + + + + + + BO2 C R + + + + + + BO3 D C + + + + + + + BO4 A + R + + + + + + + + BO5 B + C + + + + + + + BO6 A + R + + + + + + BO7 A + R + + + + + + + + + + CP1 B + C + + + + + + CP2 A + R + + + + + CP3 A + R + + + + + + + CP4 D C + + + + + + + + + + + CP5 A + R + + + + + + + CP6 C R + + + + + + + + + CU1 C R + + + + + + + + CU2 C R + + + + + + CU3 D C + + + + + CU4 B + C + + + + + - 105 12 - 13 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 14 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - 15 + + + + + + + + + - 16 + + + + + + + + + - 17 + + + + + + + + - Complementary Copy Postharvest microbial diversity on major cultivars of Indian mangoes CU5 CU6 CU7 CU8 CU9 DP1 DU1 DU2 DU3 DU4 KG1 KG2 KG3 KG4 KG5 KG6 KG7 KG8 KG9 KG10 KM1 KM2 KM3 KM4 KM5 KM6 KM7 KM8 MB1 MB2 MB3 MB4 MB5 MB6 LU1 LU2 LU3 LU4 MO1 MO2 MO3 MO4 MO5 MO6 MO7 MO8 MO9 NT1 NT2 NT3 NT4 NT5 NT6 NT7 NT8 NT9 NT10 NT11 NT12 NT13 NT14 Postharvest microbial diversity on major cultivars of Indian mangoes D D C C D C D C C A C B D A D B A B C A A A C A C A A C B C C D D C A A C B B A D B D B C C C C A D D C A C A A C A B D B + + + + + + + + + + + + + + + + + + + + + + + + + + + C C R R C R C R R R R C C R C C R C R R R R R R R R R R C R R C C R R R R C C R C C C C R R R R R C C R R R R R R R C C C + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + - - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - + + + + + + + - Complementary Copy 106 G=Gram reaction, N=Negative staining, S=Spore staining, A=Acid fast staining, P=Pigmented colony, T=Transparent colony, S=Smooth edge on colony. Biochemical characteristics: 1=Lactose fermentation 2=Casein Hydrolysis 3=Starch hydrolysis 4=Flouroscein production 5=Peroxidase reaction 6=Gelatin hydrolyis 7=Methyl red test 8=Voges-Proseuker test 9=Urease test 10= Indole production test 11=Citrate utilization test 12= Hydrogen sulphide production test 13=Glucose fermentation test 14= Oxidase test 15 = Cellulose degradation test 16=Pectate lyase production test 17= Pectinase production test Postharvest microbial diversity on major cultivars of Indian mangoes 107 Table 4. Mold diversity on different mango cultivars from different parts of India Alphonso, Maharashtra Isolate AM01 AM02, 07, 10 AM08 AM03, 04, 06 AM05, 13 AM09 Alphonso, AK02,0 4 Karnataka AK03 Baganpalli, BA02 Andhra Pradesh BA08 Baganpalli, Orissa BO03 Chausa, Punjab CP01, 03 CP02 Chausa, CU01 Uttar Pradesh CU04 CU03 CU06 Dashehri, Punjab DP01 DP02 DP03 DP04 Kesar, Gujarat KG01 KG02 KG03 Kesar, Maharashtra KM01, 02 Langra, LU01 Uttar Pradesh LU02 LU03 Maldah, Bihar MB01 MB03 Mallika, Orissa MO05 MO01 MO06 MO02 MO03 Neelam, NT01 Tamil Nadu NT02 NT03, 4 Fungus Evenness / Relative Abundance, RA (%) Species 9.09 A. fumigatus 27.27 A. flavus 9.09 A. niger 27.27 Fusarium F. solani 18.18 Alternaria A. alternata 9.09 Cladosporium C .cladosporioides 66.66 Aspergillus A. niger 33.33 A. flavus 50 Aspergillus A.terreus 50 Pencillium P. citrinum 100 Aspergillus A. niger 66.67 Aspergillus A. fumigatus 33.33 Pencillium P. chrysogenum 25 Fusarium F. moniliforme 25 F. oxysporum 25 Aspergillus A. flavus 25 A. fumigatus 25 Fusarium F. pallidoroseum 25 Aspergillus A. niger 25 A. nidulans 25 A. fumigatus 33.33 Fusarium F. moniliforme Aspergillus A. fumigatus 33.33 33.33 A. flavus 100 Aspergillus A. niger 33.33 Alternaria A. alternata 33.33 Aspergillus A. niger 33.33 Heminthosporium H. spiciferum 50 Aspergillus A. fumigatus 50 Trichoderma T. longibrachiatum 20 Fusarium F. pallidoroseum 20 Pencillium P. chrysogenum 20 P. oxalicum 20 Aspergillus A. terreus 20 A. niger 25 Aspergillus A. flavus 25 A. terreus 50 A. niger Genera Aspergillus a principal spoilage microbe of both fresh-cut and fresh vegetables. Buick and Damoglou (1987) found that E. carotovora was the dominant spoilage microorganism on sliced carrots packed in air, consisting of more than 80% of total detectable microflora. Robbs et al. (1996) identified Erwinia in 5 of 16 soft-rot samples of fresh-cut celery. Erwinia had been reported to produce pectinolytic enzymes, which cause degradation of cell wall leading to soft rot disease (Lund, 1983). All the bacterial isolates were tested for presence of hydrolytic enzymes. Out of 123 isolates, 50 showed cellulase activity and 32 showed pectin hydrolysis out of which 17 showed production of pectatae lyase and 15 showed production of polygalacturonase. Such microbes having capability of producing hydrolytic enzymes may use it to overcome plant defence mechanisms and gain access to plant nutrients. The pectolytic enzymes, including pectin methyl esterase (PME), polygalacturonase (PG), pectin lyase (PNL), and pectate lyase (PL), can degrade pectins in the middle lamella of the cell, thereby resulting in liquefaction of the plant tissue leading to conditions such as soft rot. Besides, many strains of Bacillus and Erwinia had been reported to show antagonistic effect against pathogens causing black spot Species Richness Simpson’s index (D) Simpson’s index of Diversity (1-D) 6 0.17 0.83 2 0.56 0.44 2 0.50 0.50 1 1.00 0.00 2 0.56 0.44 4 0.25 0.75 4 0.25 0.75 3 0.33 0.66 1 1.00 0.00 3 0.33 0.66 2 0.50 0.50 5 0.20 0.80 3 0.37 0.63 Complementary Copy Mango cultivar of mango (Pruvost and Luisetti, 1991). Okigbo and Osuinde (2003) reported bio-control of fungal leaf spot disease of mango with Bacillus subtilis. In South Africa, concerted efforts had been made to develop biocontrol agent against anthracnose disease of mango (Burger and Korsten, 1988). Korsten et al. (1991) reported effective reduction in the incidence of the disease when Bacillus licheniformis was used as either pre or postharvest application. They further reported that the efficacy of the biocontrol agent could be further improved when it was applied with recommended fungicide used at lower concentration (Korsten et al., 1992, Silimela and Korsten, 2001). Bacillus licheniformis is now available in commercial formulation (Mango green), and is reported to effectively reduce the fungal population from mango surface (Govender et al., 2005). Fungal diversity: Altogether 47 filamentous fungal isolates were purified from mango fruit surface of nine mango cultivars and among them the most abundant genera was Aspergillus followed by Fusarium and Pencillium with a relative abundance (RA) of 60.00, 17.00 and 8.00 %, respectively. Other fungi identified in minority belonged to genus Alternaria, Cladosporium, Helminthosporium and Trichoderma. 108 Postharvest microbial diversity on major cultivars of Indian mangoes Among the genus Aspergillus, the dominant species were A.niger, A. flavus and A. fumigates., while the genus Fusarium was dominated by F. monoliforme. Aspergillus species are highly aerobic and widespread in nature, being found on fruits, vegetables and other substrates which may provide nutriment, where they commonly grow as molds on the surface of a substrate, as a result of the high oxygen tension. Some species of this genus are involved in food spoilage (Pelczar et al., 2008). Acknowledgement Aspergillus niger and Aspergillus flavus were found to be most common on mango cultivars representing 23.00 and 15.00 % of the total fungal isolates, respectively. Aspergillus niger is reported to cause black mould disease on certain fruits and vegetables such as grapes, onions and peanuts and is a common contaminant of food. It is ubiquitous in soil and is commonly reported from indoor environments (Frazier and Westhoff, 2008). Fungal composition did not vary much among the cultivars however, maximum species richness was found on AM followed by MO, CU and DP while lowest on BO and KM. Alphonso mango harvested from Maharastra (AM) showed presence of 11 fungi belonging to genus Aspergillus, Fusarium, Alternaria and Cladosporium with RA 45.45, 27.23, 18.18 and 9.09 %, respectively, thereby exhibiting highest Simpson’s index of diversity (measure of the probability that two individuals randomly selected from a sample will belong to the same species.) amongst various mango cultivars under study (Table 4). While cv. BO and KM showed the presence of Aspergillus niger only and hence, depicting lowest species richness and Simpson’s diversity index (Table 4). Tournas and Katsoudas (2005) also reported the dominance of Alternaria, Cladosporium, Penicilium, Fusarium, Trichoderma, Geotrichum, Rhizopus and A. niger in their study with citrus fruits. Ali Khan, M.W. and M. Ahmad, 2006. Detoxification and bioremediation potential of a Pseudomonas fluorescens isolate against the major Indian water pollutants. J. Environ. Sci. Health Part A Toxic/ Hazardous Subsances Environ. Eng., 41(4): 659-674. Atlas, R.M. and J.W. Snyder, 2006. Handbook of Media for Clinical microbiology. CRC Press, London. Arauz, L.F. 2000. Mango anthracnose: economic impact and current options for exported mango. Plant Disease, 84: 600-611. Barnby, F.M., F.F. Morpeth and D.L. Pyle, 1990. Endopolygalacturonase production from Kluyveromyces marxianus. I. Resolution, purification and partial characterization of the enzyme. Enzym. Microb. 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Microbial alkaline pectinases and their industrial applications - A review. Appl. Microbiol. Biotechnol., 59: 409-418. Jha, S.N., P. Jaiswal, K. Narsaiah, R. Bhardwaj, R. Sharma, R. Kumar and A. Basedia, 2010. Postharvest micro-flora on major cultivars of Indian mangoes. Scientia Hort., 125(4): 617-621. Joshi, S.R. 2008. Influence of roadside pollution on the phylloplane microbial community of Alnus nepalensis (Betulaceae). Rev. de boil. Trop., 56(3): 1521-1529. Korsten, L., J.H. Lonsdale, E. De Villiers and E.S.De Jager, 1992. Preharvest Biological Control of Mango Diseases. South African Mango Growers Association Yearbook, 12: 72-74. Current study showed that mango surface harbored a huge microbial diversity, which comprised varietal as well as regional variation. In general, Gram positive rods showed predominance in bacterial community and Aspergillus spp. in fungal community. The highest fungal diversity was observed in variety AM, followed by MO, CU, DP, KG, LU, NT, BA, MB, AK, CP, BO, KM. This study is an important step in identification of spectrum of microbial community on mango surface which will be helpful in devising measures to reduce the effect of spoilage and pathogenic microbes. Further, the available bio-resources on mango surface can be used to screen the potential micro-flora with a role in biocontrol of plant diseases, for production of metabolite/enzyme of commercial importance or for the development of instrumental methods such as biosensors, spectroscopic instruments, etc. for rapid detection of microbial as well as physico-chemical characteristics. References Complementary Copy The fungal isolates were tested for presence of hydrolytic enzymes (cellulases and pectinases) and results indicated that 6 out of 47 isolates showed presence of one or more hydrolytic enzymes (data not shown). 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