• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.375-386
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• 2022

In the present study, four distinctly colored bacterial isolates that show intense pigmentation upon brief ultraviolet (UV) light exposure are chosen. The strains are identified as Micrococcus luteus (Milky yellow), Cryseobacterium pallidum (Yellow), Cryseobacterium spp. (Golden yellow), and Kocuria turfanensis (Pink) based on their morphological and 16S rDNA analysis. Moderate salinity (1.25%), 25-37℃ temperature, and pH of 7.2 are found to be the most favorable conditions of growth and pigment production for all the selected isolates. The pigments are extracted using methanol: chloroform (1:1) and the purity of the pigments are confirmed by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Further, Fourier transform infrared (FTIR) and UV-Visible spectroscopy indicate their resemblance with carotenoids and flexirubin family. The antioxidant activities of the pigments are estimated, and, all the pigments have shown significant antioxidant efficacy in 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picryl-hydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays. The UV protective property of the pigments is determined by cling-film assay, wherein, at least 25% of UV sensitive Escherichia coli survive with bio-pigments even after 90 seconds of UV exposure compared to control. The pigments also hold a good sun protective factor (SPF) value (1.5-4.9) which is calculated with the Mansur equation. Based on these results, it can be predicted that these bacterial pigments can be further developed into a promising antioxidant and UV-protectant for several biomedical applications.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1536-1541
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• 2018

A yellowish, flexirubin-pigment-producing strain $I3-3^T$ was isolated from river water in Iksan, the Republic of Korea. The strain was gram-negative, aerobic, non-motile, showed catalase and oxidase activities, and could grow at a temperature range of $10-35^{\circ}C$, pH 5.0-10 and 0-2.0% (w/v) of NaCl. The major fatty acids were iso-$C_{15:0}$, iso-$C_{17:0}$ 3-OH and summed feature 3 (comprising $C_{16:1}{\omega}7c$ and/or $C_{16:1}{\omega}6c$). The isolate contained phosphatidylethanolamine, one aminolipid, and two unidentified lipids as the major polar lipids. Menaquinone-6 (MK6) was the major respiratory quinone. The G+C content of the genomic DNA of strain $I3-3^T$ was 35.6%. Comparison of the 16S rRNA gene sequence with the sequences of the closely related type strains showed highest sequence similarity of 96.95% and 96.93% to Flavobacterium nitrogenifigens $NXU-44^T$ and Flavobacterium compostarboris $15C3^T$, respectively. Based on phenotypic and phylogenetic distinctiveness, strain $I3-3^T$ is considered as a member of novel species within the genus Flavobacterium, for which Flavobacterium amnigenum sp. nov. is proposed. The type strain is $I3-3^T$ (=KCTC $52884^T$ =NBRC $112871^T$).

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.371-378
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• 1998

Five strains of gram-negative and yellow-pigmented bacteria were recently isolated from diseased freshwater fishes in Korea. All isolates were confirmed as a known fish pathogen of columnaris disease, Cytophaga columnaris based on their colonial and cellular morphology, and on physiological, biochemical and antigenic characteristics. Although the isolates were from different fish species, their characteristics of them were very similar to those of the reference strains of C columnaris (NCMB $2248^T$ and EK 28). Also, profiles of OMPs of Korean isolates were similar to those of the reference strain, C columnaris NCMB $2248^T$ when analyzed by SDS-PAGE.