Investigation on antibacterial, probiotic and plant growth promoting attributes of Enterococcus faecium MYSBC14 from Blue Cherry

Abstract

In this investigation, Blue Cherry fruit was used to isolate potential probiotic isolate and characterized for their beneficial attributes. The main objective of the study was to evaluate the antagonistic activity of the isolated bacteria against plant pathogenic bacteria such as Ralstonia solanacearum, Pectobacterium carotovorum sub sp. carotovorum and Xanthomonas oryzae pv oryzae and also to evaluate the isolate for potential probiotic, plant growth promoting and biocontrol activity. A total of nine isolates were isolated from Blue Cherry fruit and initially screened for microscopic and biochemical characters. The agar-well diffusion method, paper disc, spot inoculation and microplate method were used to test the antibacterial activity from the cultured supernatants against plant pathogenic bacteria and zone of inhibition ranged from 0.6 to 2.1 cm and per cent inhibition of plant pathogenic bacteria ranged from 64.81 to 71.70 %. Effective isolate MYSBC14 was genotyped based on 16S rDNA and identified as Enterobacter faecium OL454757. Effective isolate E. faecium MYSBC14 was further characterized for probiotic properties, PGPR and bio-control attributes. MYSBC14 survived under pH 2 and pH 4 after 2 and 4 h after incubation (38.08 and 23.16 %, 87.90 to 82.02 % respectively) and was susceptible to majority of antibiotics evaluated. A survival rate of 52.67 and 43.01 % was recorded at 0.3 % oxgall salt concentration after 2 and 4 h after incubation. The cell surface hydrophobicity of 90.24 % and auto aggregation of 8.10 to 22.02 % represented the adhesion properties of the isolate. MYSBC14 showed indole acetic acid production (11.56 µg/mL), gibberellic acid production (10.18 µg/mL) and gave positive results for solubilization of phosphate, potash, protease and siderophore production and was found negative for zinc and silicon solubilization, cellulose degradation activity, HCN production activity and amylase activity. The findings of the present investigation showed that isolated probiotic organism possesses promising antibacterial, probiotic attributes, plant growth promoting characteristics and bio-control traits.