Purpose To characterize and optimize the productivity of melanin using an extremotolerant actinobacterium, Dietzia schimae NM3, for the first time. Methods An extracellular brown pigment produced by D. schimae NM3 in the nutrient broth and cheese whey medium by adding L-tyrosine. The extracted melanin was analyzed by UV-visible, HPLC, and FTIR assays. The radical scavenging activity (by DPPH) and sun protection factor (SPF) of the extracted melanin were measured. The melanin cytotoxicity was assayed by MTT and chromate biosorption was measured by atomic absorption spectroscopy. Finally, melanin production by D. schimae NM3 was optimized by response surface methodology (RSM) using Box-Behnken design in the whey medium. Result The purified melanin showed similar peak to the standard melanin (SIGMA) at 3.5 min in HPLC, and C=O bands, NH2, CH, C-N, and aromatic groups by FTIR. The radical scavenging activity (by DPPH) and SPF of the extracted melanin were obtained 188.9% and 20.22, respectively. Using MTT assay, the melanin revealed non-toxic effect on the normal human fibroblast (HFB) cell culture. The melanin yield 790 mg l−1, and tyrosinase activity 3400 U ml−1 were obtained in the medium contained whey powder [5% (w v−1)], L-tyrosine 2.5 g l−1, CuSO4 0.013 g l−1, and pH 10.5, incubated at 32 °C for 3 days. The ANOVA results indicated significant P-value, model F-value, and probability, with insignificant lack of fit. After optimization with mono-factors, the nutrient broth came up with melanin yield as 1.2 g l−1 and tyrosinase activity as 4040 U ml−1. Conclusion This is the first report of melanin production by D. schimae NM3 and this natural melanin showed valuable biological properties such as high antioxidant activity and radioprotection (SPF) and the biocompatibility to human cell line.
Aims: Bacterial melanins are UV-absorber biopolymers with potential applications in cosmetics and pharmaceutical industries. However, the cost concern of these pigments remains a limiting factor for their commercial production. Hence, the present study was aimed to isolate a bacterium with high yield of melanin by optimization of an inexpensive waste sources. Methods and Results: Pseudomonas koreensis UIS 19 (accession number: MG548583), which displayed significant bioproduction of melanin along with high tyrosinase enzyme activity was isolated from soil and introduced as a melanin-producing bacterium. Scanning and transmission electron microscope studies revealed that melanin pigments accumulated inside as well as the extracellular space of the cells. Melanin was extracted from the isolated strain and its detection was investigated using NMR and HPLC analyses. Here, we showed that the DPPH radical scavenging activity of 20 mg ml −1 melanin extracted from the isolated strain was >92Á42% and its sun protection factor (SPF) value was 61Á55. Melanin production by the UIS 19 in molasses medium showed sugar consumption (32 g l −1 ) for biomass production (5Á4 g dry wt) and melanin yield of 0Á44 g dry wt g −1 biomass from L-tyrosine. Some critical intermediated such tyramine, l-dopa, dopamine and dopaquinone related to the melanin Raper Mason pathway were detected by H-NMR. Furthermore, to achieve high bioproduction of melanin in inexpensive media include 5% molasses 5 Brix as an industrial waste, nutritional and environmental parameters were screened using response surface methodology by Box-Behnken design in which, maximum melanin yield of 5Á5 g dry wt l −1 was obtained. Conclusions: The bioproduction of melanin as valuable compound from P. koreensis was performed using an optimized waste medium. The purified melanin showed high radical scavenging activity and high SPF value. Significance and Impact of the Study: Pseudomonas koreensis UIS 19 is a promising candidate for industrial production of melanin as cosmetic skin-care product.
Background Nurse stations are one of the primary units for supporting effective functioning of any hospital. They are important working environments that demand adherence to known ergonomic principles for the well-being of both staff and patients. The aim of this study was to develop a psychometrically tested tool for the assessment of the ergonomic conditions of nurse workstations in hospitals. Methods Ten hospitals, with a total of 133 nurse stations participated in this mixed-methods research. The domains and items of the tool were developed based on a literature review, an experts’ panel, and interviews with nurses. Results The final nurse station ergonomic assessment (NSEA) tool has good psychometric properties. Validity was assessed by face validity and content validity. Reliability was evaluated using inter-rater agreement and test-retest reliability analyses with a four-week interval between assessments. The NSEA is comprised of 64 items across eight domains: layout and location (7 items), workspace (11 items), security-safety (5 items), environmental conditions (8 items), counter (8 items), chair (13 items), desk (9 items), and monitor (3 items). Conclusions The NSEA adds to the literature a tool for managers to ensure they comply with legal requirements and support best practice for those working on hospital wards. The NSEA can be used to identify challenges for healthcare professionals who use nurse stations and support the execution of targeted interventions to improve human-environment interactions.
Melanin is a natural, dark-brown complex molecular structure pigment formed by the oxidative polymerization of phenolic compounds. Microbial melanin pigment can be use in industrial fields, canned additives and preservatives. Optimization method is used to produce a quick and sufficient product with reliable and cost-effective processes. In this project, four factors (temperature, l-tyrosine, pH and CuSO4) affecting in melanin production by Dietzia schimae NM3 were optimized by response surface methodology with Box–Behnken design in inexpensive medium (whey powder). The anti-bacterial activity of D. schimae melanin was assayed by disk diffusion test. The optimal medium compositions were obtained in whey 5% (w/v), l-tyrosine 2.5 g/l, CuSO4 0.013 g/l, pH 10.5, and temperature 32 °C by maximum yield of 790 mg/l melanin pigment. The ANOVA results of RSM showed a significant P-value (0.0001), model F-value (78.84) and probability R² (0.98), with insignificant lack of fit (0.091). Melanin also showed antibacterial activity against gram-positive strains such as Bacillus cereus (20 mm), B. subtilis (18 mm), Streptococcus pyogenes (17 mm), Staphylococcus epidermidis (18 mm), and S. aureus (18 mm), which was comparable with amoxicillin (AMX) and cefotaxime (CTX) as control positives. We realized the ability of D. schimae melanin pigment as natural substances to be considered for industrial fields due to its biocompatibility and physicochemical properties.
Background: Melanin is a negative charge hydrophobic complex pigment. Melanin is produced naturally in bacteria to protect them against UV, free radicals and environmental stresses. Pigment production in bacteria has more advantages than other biosources due to its rapid growth, higher efficiency and easier extraction. The aim of this study was the isolation, biochemical and molecular identification the melanin pigment producing bacterium in the presence of l-tyrosine and the evaluation of the pigment biological properties. Materials & Methods: The soil sample was collected from the University of Isfahan Park, and cultured in nutrient agar medium containing l-tyrosine. The colony with brown halo was isolated and identified using phenotypic and molecular methods. The bacterial growth and melanin production were evaluated by spectrophotometry at 600 and 400 nm, respectively. The melanin pigment was extracted by increasing the acidity of the broth culture supernatant. The melanin production yield, antioxidant activity and sun protection factor (SPF) of melanin were determined. Results: Pseudomonas stutzeri strain UIS2 capable to grow in nutrient agar and melanin production, was isolated and registered in NCBI GenBank with accession no. MG519615. The maximum melanin production was obtained 600 mg l-1 by isolated strain. The antioxidant property of melanin in DPPH test was determined as 74.9% and its SPF was 49.05 U/mL. Conclusion: The melanin pigment from the isolated Pseudomonas showed high SPF and high antioxidant activity against ROS stresses. So, it can be suggested as a suitable candidate for application in cosmetic, pharmaceutical, and environmental decontaminant.
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