Isolation, Characterization and Screening of Microbial Melanin for its role in Protection of Plant Growth Promoting Bacteria

Abstract

Plants are susceptible to vulnerable impacts caused by presence of heavy metals, viruses, bacteria, fungi, insects and pests. Along with diseases, availability of nutrients, water, temperature and the role of protecting the role plant growth promoting bacteria (PGPB) is also a matter of concern. PGPB may promote plant growth directly usually by either facilitating resource acquisition or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various heavy metals on plant growth and development. Although a significant increase in the use of PGPB in agriculture was observed in the last two decades, there is a dearth of long-term studies addressing the effects of PGPB on existing microbial community structure. Melanin is a negative charge hydrophobic complex pigment that is a substance made of small particles virtually insoluble in the environment and is usually used for its color, protective or other characteristics. Melanin, its ability to chelate metals by which the toxicity of metals can be reduced. In this direction, soil and vegetable waste samples were collected and enriched. A total of fourteen isolates were obtained and these isolates were screened for melanin production. Black brownish colonies were melanin positive colonies. These isolates were subjected to production of melanin. Melanin was extracted and subjected to FTIR (Fourier Transform Infrared Spectroscopy). On the basis of FTIR results, melanin was confirmed and then tested for its metal chelating ability followed by its application as protectant for plant growth promotion. Significant growth was observed when compared with control proves its vital role in plant growth promotion