P. Selvi, P. Iyer
Sep 1, 2018
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International Journal of Life-Sciences Scientific Research
Abstract
Bacterial pigments have many applications in the current day to day life. The pigments produced by chromobacteria can be used for various applications like dairy, pharmaceutical, and food etc. In this study, three types of pigments were isolated i.e. yellow from Xanthomonas sp., pinkish red from Rhodotorula sp., and orange from Sarcina sp. Pigmented bacterial isolates were obtained from the soil samples and used for the pigment extraction study. We studied that the pigment producing bacteria and identified the color producing pigments. Soil samples from Pondicherry, Cuddalore, Chennai, and Andhra sea coast were collected and used for isolation of microbes producing pigments. Purification of extracting pigments was done by column chromatography, whereas identification and characterization of purified pigment done by UV-Visible spectrophotometry and GC/MS analysis etc. The pigment isolated from bacterial sp. were used for the antimicrobial activity, antioxidant, and anticancer & transformation studies. The bacterial extracts of carotenoid pigment extracted and used as natural colorants for food products and dying of cloth. Key-words: Carotenoid, GC/MS analysis, Pigment extraction, Soil samples, UV-Visible spectrophotometry INTRODUCTION Carotenoids are a class of compounds that have coloring power and have been widely used in food industry, leading its market to full development. Carotenoids occur widely in nature and, in general, all fruits and vegetables of color are good sources of these compounds . Microorganisms are the most versatile tools in biotechnology to produce variety of molecules including enzymes, antibiotics, organic acids and pigments. Recent studies have shown that microorganisms are a promising source for natural colors. The presence of pigments has been reported among the entire microbial world including bacteria, fungi, yeast, algae and protozoa. How to cite this article Selvi PS, Iyer P. Isolation and Characterization of Pigments from Marine Soil Microorganisms. Int. J. Life Sci. Scienti. Res., 2018; 4(5): 2003-2011. Access this article online www.ijlssr.com Industrial production of natural food colorants by microbial fermentation has several advantages such as cheaper production, easier extraction, higher yields through strain improvement, no lack of raw materials and no seasonal variations . Pigments are compounds with characteristics of importance to many industries. In the food industry they are used as additives, color intensifiers, antioxidants, etc. Pigments come in various colors, some of which are water soluble . Microorganisms are the most powerful creatures in existence and determine the life and death on this planet. MATERIALS AND METHODS Sample CollectionSoil samples were collected from different marine sources of India such as (Pondicherry, Cuddalore, Chennai, Tuticorin, and Andhra sea coast). After the collection of soil samples from different coastal areas, further study was done at the Department of Biotechnology Women’s Christian College, Chennai, India. The collected soil samples were stored at 4°C for further study. Research Article Int. J. Life Sci. Scienti. Res. eISSN: 2455-1716 Selvi and Iyer, 2018 DOI:10.21276/ijlssr.2018.4.5.7 Copyright © 2015–2018 | IJLSSR by Society for Scientific Research under a CC BY-NC 4.0 International License Volume 04 | Issue 05 | Page 2004 Isolation of pigment producing bacteria from Soil samplesPondicherry, Cuddalore, Chennai, Tuticorin, and Andhra sea coast. Identification of pigment producing bacterial species Cultural characteristicThe isolated pure culture was maintained in nutrient agar slant for further experimental use. Morphological characteristicThe bacterial species were subjected to Gram staining for morphological identification. Biochemical characteristicThe isolated bacterial sp. were subjected to the following biochemical tests i.e. Indole test, methyl red and voges proskauer test, citrate test, oxidase test, catalase test, triple sugar iron agar test, urease test, and carbohydrate fermentation test. Test for carotenoids in bacteriaThe bacterial cell isolates were grown in Luria Bertini broth and the pigments were extracted from the organisms. Carotenoid pigments were identified the using of UVVisible spectroscopy ranging from 450 nm to 600 nm . Thin layer chromatography (TLC)Silica gel TLC plates are cut as per need. The bacterial pigment extracts, the carotenoid yellow, orange, pink red pigment spots observed were marked and Rf value determined . Isolation of carotenoid pigments by column chromatographyThe bacterial pigments were purified by column chromatography whereas, the fractions collected were evaporated and the thickly concentrated carotene fractions are used for TLC. The stationary phase of silica gel (100–200 μm) and mobile phase of chloroform: methanol 95: 5 [6] was used. Determination of the antimicrobial activity of the bacterial pigmentsThe antimicrobial activity was checked by 2 different methods (phosphomolybdenum method and H2O2 scavenging assay) [7] given belowTotal antioxidant activity by phosphomolybdenum methodThe phosphomolybdenum assay [8] used for determining the antioxidant capacity was based on the reduction of Mo (VI) Mo (V) by the antioxidants and subsequent formation of a green phosphate/Mo (V) complex at acidic pH. Hydrogen peroxide (H2O2) scavenging assayThe ability of the extracts to scavenge hydrogen peroxide was determined and calculated [9] by given below formula: % scavenged (H2O2) = (A of control–A of test / A of control) X 100 whereas, A= Absorbance Reducing power assayA spectrophotometric method reducing power assay [10] was used for the measurement of the reducing power of the sample. GC-MS analysisThe Clarus 680 GC was used in the analysis employed a fused silica column, packed with Elite-5MS (5% biphenyl 95% dimethylpolysiloxane, 30 m × 0.25 mm ID × 250 μm df) and the components were separated using Helium as carrier gas at a constant flow of 1 ml/min. The injector temperature was set at 260°C during the chromatographic run. Total 1 μL of extract sample injected into the instrument the oven temperature as follows: 60°C (for 2 min); followed by 300°C at the rate of 10°C min, where it was held for 6 min. Mass detector conditions were transferred line temperature 240°C; ion source temperature 240°C and ionization mode electron impact at 70 eV, scan time 0.2 sec and scan interval of 0.1 sec. The spectrums of the components were compared with the database of spectrum of known components stored in the GC-MS NIST (2008) library. Confirmation test for carotenoidsThe bacterial cell isolates were grown in LB broth in a rotary shaker at 120 rpm and 37°C temperature. After 3 days, the cells were subjected to centrifuge at 8000 RPM for 10 minutes at 4°C. Discard the supernatant and the pellet collected. Collect pellet with distilled water and spin at 4000 RPM for 15 minutes. Collected pellet with 5 ml methanol and incubated in water bath 60°C for 15 minutes. Again centrifuge at 4000 RPM for 15 minutes and collected the supernatant and filter through Whatman filter paper and collected the bacterial extracts of yellow, orange, and pink red. To the extracts of carotenoid pigment added 1 ml of sulphuric acid in 9 ml of water. The appearances of blue color confirm the presence of the carotenoids . Transformation study– A single colony was picked from a freshly grown plate of E. coli DH5α and inoculated in the 100 ml of LB broth and kept for overnight incubation Int. J. Life Sci. Scienti. Res. eISSN: 2455-1716 Selvi and Iyer, 2018 DOI:10.21276/ijlssr.2018.4.5.7 Copyright © 2015–2018 | IJLSSR by Society for Scientific Research under a CC BY-NC 4.0 International License Volume 04 | Issue 05 | Page 2005 at 37°C with vigorous shaking for approximately 3 hours. Cell density was monitored by determining OD600 nm and it should be less than 10 cells/ml (log phase of growththe healthiest in bacteria). The culture was subjected to centrifugation at 6000 rpm at room temperature for 5 minutes and the pellet was re-suspended with 0.1 M ice cold calcium chloride. The aliquot was taken in prechilled vial along with plasmid DNA and gently tapped and incubated in ice for 20 minutes. The cells were subjected to heat shock for uptake the plasmid DNA by placing in 42°C water bath for 20 minutes, then returned to ice to chill immediately for 5 minutes . Anticancer activity of the extracts MTT assayCancer cell lines were purchased from Cancer Institute, Chennai. The cells were grown in the 96 well plate in Dulbecco’s Modified Eagle Medium, supplemented with 10% fetal bovine serum and antibiotics (Penicillin-G). About 200 μl of the cell suspension was seeded in each well and incubated at 37C 48 hours with 5% CO2 for the formation of monolayer of cells. The monolayers of cells in the plate were exposed to various concentrations of the bacterial carotenoid pigment and were incubated for 24 hours. Cytotoxicity was measured using MTT (5 mg/ml). After incubation at 37°C in a CO2 incubator for four hours, the medium was discarded and 200 μl of DMSO was added to dissolve the formazan crystals. The absorbance was read in a micro-plate reader at 570 nm . Test for carotenoidsThe bacterial carotenoid pigment (2 ml) extract from the purified compound from column chromatography was mixed with alum potassium aluminium sulphate (6%). The cotton fabric and thread was kept immersed in the solution for about 5 minutes and kept for drying . Washing performanceDried cotton fabrics were soaked in the detergent solution for 20 minutes and then washed using tap water and dried for 30 minutes. The bacterial pigment purification carotenoid pigments were applied as food colorants. RESULTS The microorganisms were identified on the basis of Gram staining and Biochemical characteristics. The Table 1 shows the all the microorganisms were Gram negative but each one giving different color pigments. Table 1: Gram staining characterization of selected bact