English

Raju Radhajeyalakshmi,Vinodhana Natarajan Kumari,Kalipatty Nalliappan Ganesan,Kandhasamy Sethuraman,Chandrasekaran Bharathi,Gandhi Karthikeyan

doi:10.5897/ajmr2016.8265

Abstract

Cyclic lipopeptides (CLPs) with antibiotic, biosurfactant producing fluorescent pseudomonads were isolated from sugar beet-maize intercropped in sandy loam soils at Maize Research Station, Vagarai, TNAU. Approximately 20 fluorescent pseudomonads from sandy loam soils were isolated by using two different growth media. The strains were distinguished based on their growth, CFU/g, fluorescence, and pigment production. Growth inhibition of maize pathogens by CLP producing fluorescent pseudomonads strains were studied by dual culture experiments. The impact of CLP producing flurorescent pseudomonads strain on the zoospores of Downy mildew pathogen of maize was studied by direct microscopy and encysted zoospores were observed. Invitro, biochemical experiments confirmed the presence of Viscosinamide producing strain among the fluorescent pseudomonads isolates in terms of utilization of C and N sources. The particular strain was tested for its growth promoting activity by treating the maize seeds for their germination, and seedling vigour performance. Fluorescent pseudomonads can be affiliated to group under CLP producing biotypes/biovars. Purification of CLP (Viscosinamide) and characterization by HPLC analysis was carried out. Pot culture experiments were conducted to test the performance of CLP producing Pf strains in maize crop for testing their disease resistance. These biovars with antibiotic properties are the potential targets for the disease management in maize. CLPs in general receive considerable attention as potent antimicrobial drugs. Key words: Cyclic lipopeptides, fluorescent pseudomonads, viscosinamide, zoospores, antifungal.

Highlights

Biosurfactants are found to be structurally diverse in nature and are commonly synthesized by micro-organisms
Cyclic lipopeptides (CLPs) with antibiotic, biosurfactant producing fluorescent pseudomonads were isolated from sugar beet-maize intercropped in sandy loam soils at Maize Research Station, Vagarai, TNAU
The impact of CLP producing flurorescent pseudomonads strain on the zoospores of Downy mildew pathogen of maize was studied by direct microscopy and encysted zoospores were observed

Summary

Introduction

Biosurfactants are found to be structurally diverse in nature and are commonly synthesized by micro-organisms. Biosurfactants have been commonly classified as: (i) Low molecular-weight molecules, which decrease surface tension efficiently; and (ii) High-molecular weight polymers which bind to surfaces (Rosenberg and Ron, 1997). Low-molecular weight biosurfactants belongs to the classes of glycolipids or lipopeptides. Large group of microbes are capable of producing biosurfactants, which includes Pseudomonas spp. strains producing rhamnolipids (Lang and Wullbrandt, 1999; Providenti et al, 1995; Shreve et al, 1995) and Bacillus sp. Within the group of biosurfactant producing microbes, fluorescent pseudomonads received more attention for the past two decades (Hotte and Altier, 2010; Raaijmakers and Mazzola, 2012; Olorunleke et al, 2015)

Methods

Results

Conclusion