Isolation of a novel strain of Aeromonas media producing high levels of DOPA-melanin and assessment of the photoprotective role of the melanin in bioinsecticide applications

Abstract

Aims: To isolate a bacterium that produces high yield of melanin and to examine the effect of this bacterial pigment on the efficacy of a bioinsecticide. Methods and Results: A novel melanin‐producing bacterium, designated as strain WS, was isolated from the East Lake, Wuhan, China. Taxonomic studies of this strain indicate that it belongs to Aeromonas media. Physicochemical analysis of the pigment produced by strain WS (melanin WS) suggests that it is the authentic 3,4‐dihydroxyphenylalanine (DOPA)‐melanin. This melanin and that produced by Pseudomonas maltophilia P28 (melanin P28) share many biophysical properties, but the yield of the melanin WS is significantly higher than that of the melanin P28. In addition, the melanin WS appears to be more effective in the protection of a bioinsecticide against ultraviolet (UV) or solar radiation. At the concentration of 10 ppm, the melanin P28 exhibited no photoprotective effect on the bioinsecticide against UV radiation; in contrast, 5 ppm of melanin WS displayed an obvious protective effect. Similarly, the melanin WS displayed more protective effect on the bioinsecticide against solar radiation than the melanin P28 did over a 4‐day period, with the effect being more dramatic for the last 2 days. Conclusions: We have isolated a novel bacterial strain of A. media that produces high levels of melanin. The melanin produced by this strain offers effective photoprotection of a commercial bioinsecticide BTI against UV and solar radiation. Significance and Impact of the Study: Our study suggests that the melanin produced by our newly isolated A. media strain has the potential to be used as a general photoprotective agent for bioinsecticides.

A Putative ABC Transporter, HatABCDE, Is among Molecular Determinants of Pyomelanin Production inPseudomonas aeruginosa

“…Proposed roles for pyomelanin include the enhancement of bacterial surface attachment (20), extracellular electron transfer (61), iron reduction/acquisition (8), induction of virulence factor expression (63), heavy metal binding (21), and protection from environmental stress (11,28,32,44,53,65). A protective role has also been proposed to occur in P. aeruginosa PA14, where pyomelanin was shown to contribute to the persistence of an overproducing strain in a chronic CF infection model in mice (49).…”

Production and Characterization of Melanin from Streptomyces Cavourensis Strain RD8 Using Response Surface Optimization

“…The exploration of new novel sources of microbes is drawing attention for the production of new chemical compounds (Suthindhiran and Kannabiran, 2010). Several investigations are presented for the melanin production using actinomycetes for different applications like insecticidal (Liu et al, 1993;Wan et al, 2007), photo-protective creams (Joshua and Arturo, 2003) and pharmaceutical formulations (Sava et al, 2001;Sajiday et al, 2011). The conventional 'one-factor-at-a-time' (OFAT) method of optimization is laborious, time-consuming and unsuitable for understanding the underlying interactions (Box and Draper, 1987).…”

Draft Genome Sequence of High-Melanin-Yielding Aeromonas media Strain WS

“…That L-DOPA could be found in the bacterial culture suggested that tyrosinase may also be involved in melanin formation in strain WS (22). However, the predicted protein coincident with typical bacterial tyrosinase has not been found by searching the whole genome against HMM PF00264 yet (7).…”

“…It can enhance survival and competitive abilities of organisms via providing protection from environmental stress conditions such as UV radiation damage (21) and toxic free radicals (3). Aeromonas media strain WS was isolated from water samples collected from East Lake, Wuhan, China, and exhibits a significantly high yield of melanin (22). Our previous studies have suggested that this kind of pigment has the potential to be used as a general photoprotective agent for bioinsecticides and an active sunscreen for patients with skin photosensitivity to sun exposure (9,22).…”

“…Aeromonas media strain WS was isolated from water samples collected from East Lake, Wuhan, China, and exhibits a significantly high yield of melanin (22). Our previous studies have suggested that this kind of pigment has the potential to be used as a general photoprotective agent for bioinsecticides and an active sunscreen for patients with skin photosensitivity to sun exposure (9,22). Production of melanin has been described in many Aeromonas species (1,6,10), but the molecular determinant involved in this metabolic pathway has not been characterized.…”