Utra Violet Radiation Essay -- Environment, Purple Violet Pigment, Pho

Protection against solar UV radiations in organisms includes drudgery of secondary metabolites such as pigments that can absorb UV and manifest light. In this study, vioA gene coding for tryptophan 2-monooxygenase involved in the biosynthetic pathway of violacein-like purple violet pigment (PVP) was cloned and sequenced from an Antarctic bacterium Janthinobacterium sp. Ant5-2. A non-pigmented vioA mutant conformation was obtained following mini-Tn10 transposon mutagenesis that produced a lesser sum of extrapolymeric substances (EPS) and exhibited a compromised survival to freeze-thaw cycles at 4C. Survival of vioA mutant strain during exponential and stationary growth phase was significantly reduced when exposed to UVB (320 nm) and UVC (254 nm) (dose range 0-300 J/m) light. Decreased viability of the mutant strain was detect at 4C upon nutrient deprivation and exposure to UV light. The pigment production was augmented in surviving cells following change magnitude doses of bo th UVB and UVC. Interestingly, at higher doses i.e. 100 and 300 J/m, pigmented wild-type strain showed better survival to harmful UVC than UVB. This could be attributed to the pigment structure, which has ingress maxima in the visible (575 nm) as well as in the UVC (270 nm) range. In conclusion, this study defines the photoprotective role of the PVP in Janthinobacterium sp. Ant5-2 against UV radiation using star gene mutation. Perhaps the photoprotective role of PVP in this bacterium is one of the keystone adaptive features that define their survival in Antarctic extreme conditions, specially during austral summer months.INTRODUCTIONThe high energy photons in solar UV radiation are considered to be the most damaging fraction to the biological macromolec... ...x, which is involved in quorum sensing mediated biofilm formation (Morohoshi et al., 2010). Therefore, it is probable that loss of vioA has affected the biofilm formation in Ant5-2. Moreover, colony morphology demo that PVP had substantial effect on the structural organization of colony biofilms (Fig. 4). The mechanisms whereby pigment production control colony morphology and EPS production is likely to be a complex issue yet to be determined (Dietrich et al., 2008). Until recently, the effectiveness role of pigments as secondary metabolites modulating the cellular physiology of microorganisms in extreme environments has been ignored (Hernandez & Newman, 2001). This study provides an evidence for the role of PVP as a secondary metabolite in UV resistance and suggests its functions of primary importance in Ant5-2 residing in Antarctic extreme conditions.