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Most Pseudomonas spp. are responsible for spoilage in refrigerated foods such as alteration in flavor, texture and appearance. Samples of Minas Frescal cheese with blue discoloration were analysed and contained a high Pseudomonas concentration (7.72 ± 0.36 log CFU/g). Out of the 26 Pseudomonas isolates that were analyzed in our study, 19 demonstrated the capability of producing a diffusible dark pigment. Thus, a pigment-producing isolate (C020) was selected by rep-PCR fingerprinting and subsequently subjected to whole-genome sequencing. The draft genome assembled comprises 42 contigs totaling 6,366,75 bp with an average G + C content of 59.97%, and the species prediction performed by TYGS server, based on the draft genome sequence, identified the C020 as Pseudomonas carnis. In order to investigate the phylogenetic relationships of this isolate with strains already identified of this species, we performed an analysis based on whole-genomic sequences. First, an analysis of all P. carnis genomes deposited in GenBank to date shows that 11% (4/37) are misidentified, and belong to the Pseudomonas paracarnis species. A comparative analysis based on phylogenomic analysis has showed that there is no evolutionary relationship between P. carnis strains carrying second copies of trp genes related to blue discoloration (trpABCDF). This finding reinforces the assertion that these genes are contained in a mobile genetic element. However, it is worth noting that all strains carrying these secondary gene copies have exclusively been isolated from food sources. This observation provides valuable insights into the potential origins and dispersion dynamics of this genetic trait within the species. [ABSTRACT FROM AUTHOR]

Cold-tolerant bacteria are known to contaminate and cause defects in refrigerated foods. Defects in food products can be observed as changes in appearance, texture, and/or flavor that detract from the product's intended look, feel, or taste. Two distinct organisms were cultured from blue pigmented soymilk and tofu that had been left opened and expired in a home refrigerator. The blue coloration was reproduced when isolates were cultured in fresh, sterile soymilk. These strains also produced a variety of colony color morphologies when cultured on different media types. We report two draft genome sequences of the potential causative agents of blue discoloration of soy foods, Pseudomonas carnis strains UCD_MED3 and UCD_MED7 as well as the 16S rRNA gene sequences of co-occurring strains isolated from the defective soy samples but that did not cause blue discoloration when cultured in fresh soymilk; Serratia liquefaciens strains UCD_MED2 and UCD_MED5.

Dye sensitized solar cells have proven its potential as affordable, green method of turning solar energy into electrical energy. This article presents an extensive comparative study on dye sensitized solar cells with two types of transport layers made of ZnO nanorods and TiO2 mesoporous film, wherein bacterial pigment extracted from microorganism Serratia nematodiphila strain B2 is employed as a sensitizer. For performance enhancement via the plasmonic effect, Ag nanoparticles have been deposited onto conducting glass and used as counter electrode (CE). The efficiency and fill factor (averaged over 3 readings) are found to be approximately 2% and 43%, respectively, with TiO2 mesoporous film and 0.4% and 25%, respectively, with ZnO nanorod in the designed DSSCs. Experiments have been conducted with TiO2 film for ten weeks to evaluate the stability of the pigment. The findings suggest that bacterial pigments may possibly replace dyes, creating a new category of solar cells known as biopigment-sensitized solar cells. [ABSTRACT FROM AUTHOR]

Pigments producing strains Halobacillus yeomjeoni(81-1) Salinicoccus sp. (82-1) Bacillus infantis (63-11) Bacillus amyloliquefaciens (60-5) and Staphylococcus carnosus (48-10) were isolated from salty fermented foods. As per FTIR analysis, IR spectrum of pigment from each isolate were similar to IR spectrum of xanthophyll as previously reported. This study concluded that the pigments generated from these different halophilic strains with different color shade were all derivatives of carotenoid. Dominant bacterial pigments of these strains analyzed by High-Performance Liquid Chromatography (HPLC) compared to standard reagent included lycopene, lutein and β-carotene. Antimicrobial assays of crude pigment extract of 81-1 isolate exhibited highest inhibitory effect on Staphylococcus aureus, while 82-1 and 60-5 isolates best inhibited Escherichia coli and Bacillus cereus, respectively. DPPH assay of 60-5 isolate demonstrated significantly higher antioxidant activity as compared to others crude pigments. Furthermore, virulence analysis of strains depicted no key biogenic amine genes and no hemolytic activity in any of the isolates.

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Aims: Psychrotrophs are extremophilic microorganisms that grow optimally in low temperature having many unique bioactive molecules of biotechnological applications. In this study, we characterized a pigment from an arctic bacterium with protective activity towards UV exposure. Methods and results: The present research reports isolation and characterization of a psychrotrophic bacteria, RSAP2, from the soil sample of NyAlesund (78°56"N, 11°54"E), Svalbard, Norway. The strain showed closest 16S rRNA gene sequence similarity (99.9%) with Kocuria indica NIO‐1021. RSAP2 is a Gram‐positive, coccoid aerobe which produces a yellow pigment. The optimal parameters for pigment production while grown in LB medium were 3% (w/v) NaCl and 4 days of incubation of the culture at 20°C and pH 9 with shaking (180 rpm). The pigment was extracted in methanol and acetone (2:1) and further purified through column chromatography. It was characterized by mass spectrometry, UV–visible, fluorescence, IR, 1H NMR, 13C NMR spectroscopy and CHNS/O analysis. The pigment has a molecular weight of about 258 daltons and the molecular formula was determined as C15H18N2O2 and is a quinoline derivative. We show that the pigment can protect Escherichia coli against UV‐mediated mutagenesis. We further demonstrate that the pigment displays a significant antimicrobial effect and in sublethal concentrations it impairs biofilm formation ability of the model organism Staphylococcus aureus. Conclusions: The pigment of a psychrotrophic Arctic bacterium, most likely a strain of K. indica, was purified and its chemical structure was determined. The quinoline‐based pigment has the ability to protect live cells from UV induced damage. Significance and impact of study: Analysis and characterization of this newly isolated quinoline‐based pigment is a potential candidate for future application in skin care products. [ABSTRACT FROM AUTHOR]

The control and management of fungal diseases is a worldwide problem. A variety of microbial pigments have excellent antibacterial effects, and naturally occurring bacterial pigments may help in tackling fungal diseases. In order to explore the basic properties and biological functions of the pink pigment produced by Erwinia persicina Cp2, we used organic solvents to extract the pink pigment, analyzed the physicochemical properties of the pigment, determined the chemical composition using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and selected five pathogenic fungi to study the inhibitory effects of the pink pigment. The results showed that the main component of the pink pigment was usambarensine, which had a good light stability and a good temperature stability at room temperature (<40 °C), but the influence of the oxidant on its activity was greater than that of the reductant; simultaneously, we found that strong acids, strong alkalis, Cu2+, and Zn2+ all greatly affect the stability of the pink pigment, while Fe2+ and Fe3+ made the pigment darker. Meanwhile, the pigment could exert a good inhibitory effect against four plant pathogenic fungi: Alternaria solani, Sclerotinia sclerotiorum, Rhizoctonia solani, and Fusarium proliferatum. However, the inhibition of Fusarium oxysporum. f. sp cucumerinum decreased significantly in the later stages. This study had detected the purification process and antifungal activity on five fungi of the pink pigment of Erwinia persicina Cp2. It lays a theoretical and practical foundation for the production of related biological agents. [ABSTRACT FROM AUTHOR]

Solar cells are furthermost eminent alternative solar energy conversion devices and have great potential to conquer the energy needs of the society. In recent past, Dye sensitized solar cell (DSSC) has gained a significant research interest in research community owing to physically portable nature, simple fabrication process, customizable aesthetic look and reasonable efficiency. Regardless, it still struggles for the commercialization due to its low power conversion efficiency. Since significant dye anchoring site, light harvesting efficiency through plasmon effect and scattering effect, least undesired recombination of electrons, swift electrons transportation and greater catalytic activity etc. collectively accountable for the DSSC performance and hence the DSSC structure needs to comprehend in subsystem level (Substrate, transparent conductive oxide layer, blocking layer, semiconductive oxide layer, dye, electrolyte, counter electrode) in a single platform for the revival of cell potential. This review presented an exhaustive study on substrate, transparent conductive oxide layer, blocking layer, semiconductive oxide layer, dye, electrolyte and counter electrode respectively and addressed its development with insight discussion. Furthermore, the morphological change in semiconductive oxide layer, alteration in dye pigment based on green technology for significant light absorption and potential of liquid, quasi solid and solid states electrolyte for the revival is addressed. This review also facilitates with graphical contrast to understand and envision a direction towards determinant research scope. [ABSTRACT FROM AUTHOR]

Halochromic (pH-responsive) material was obtained by dyeing functionalized viscose fabric with a crude extract from Streptomyces sp. strain NP4. The functionalization of the fabric before dyeing was performed to make cellulose susceptible to coloration with NP4 extract. Two combined pre-treatment steps were used, oxidation to obtain dialdehyde cellulose and chitosan deposition after oxidation. Chitosan was deposited onto untreated fabric as well, while only oxidized viscose was also investigated for dyeing. Functionalization by both protocols made viscose susceptible to dyeing with the notion that the deposition of chitosan onto oxidized viscose produced the darkest shade on the material. Dyed fabrics showed visual pH responsiveness in the range pH 4–10, with a color change from pink to red (pH 4–pH 7) and a major color change from red to blue (pH 7–pH 10) whereby fabric was tested and could withstand 10 color-changing cycles. Cytotoxicity assay confirmed the non-toxic nature of dyed material, which indicates its possible use as wound dressing's indicators. [ABSTRACT FROM AUTHOR]

As an important industrial crop product, green and efficient processing technology of cotton is the direction that people have been pursuing. As a kind of natural dye with great application prospect, microbial pigment has been widely concerned in the color and functionality construction of textiles. However, at present, almost all reports on the application of microbial pigments in the cotton dyeing are using intermittent processing methods, resulting in long production process, low pigment utilization rate, large resource consumption and other problems. In this research, efficient continuous mode of color and functionality construction for cotton fabric with bacterial pigment based on nano-suspension system was developed, which possessed the advantages of short process, low cost, high pigment utilization rate, and green environmental protection. Under the optimal dyeing condition of dye bath pH 3, rolling pressure 0.75 bar, steaming time 5 min and four-dip-four-nip, dyed cotton possessed soft and uniform color, good color fastness, as well as UV protection property and certain antibacterial and hydrophobic effect. The results of visible light reflection, FTIR and XPS spectra of dyed fabrics proved that the pigments were effectively dyed onto cotton fabrics. Compared with the past dip dyeing, this continuous mode processing with prodigiosins nano-suspension had great advantages of 160% increased utilization of pigment, 80% dyeing process time and 97.8% dye liquid reduction. In addition, nano prodigiosins could not only make cotton fabric appear purplish red, but also yellow color, so that two fabric colors could be achieved with only one single pigment. Because of green environmental protection and natural health property, the dyed fabric was particularly suitable for underwear and baby clothes. The efficient color and functionality construction of cotton fabric with biomass nano pigment provided a new direction for green application of cellulose fibers. [Display omitted] • Nano prodigiosins was used for continuous mode color and functionality construction of cotton. • Efficient clean processing of cotton with bacterial pigment based on nano-suspension was developed. • The novel technique significantly reduced resource consumption and processing time. • Dyed cotton with one pigment possessed functionalities and two different colors. [ABSTRACT FROM AUTHOR]

The control and management of fungal diseases is a worldwide problem. A variety of microbial pigments have excellent antibacterial effects, and naturally occurring bacterial pigments may help in tackling fungal diseases. In order to explore the basic properties and biological functions of the pink pigment produced by Erwinia persicina Cp2, we used organic solvents to extract the pink pigment, analyzed the physicochemical properties of the pigment, determined the chemical composition using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and selected five pathogenic fungi to study the inhibitory effects of the pink pigment. The results showed that the main component of the pink pigment was usambarensine, which had a good light stability and a good temperature stability at room temperature (2+, and Zn2+ all greatly affect the stability of the pink pigment, while Fe2+ and Fe3+ made the pigment darker. Meanwhile, the pigment could exert a good inhibitory effect against four plant pathogenic fungi: Alternaria solani, Sclerotinia sclerotiorum, Rhizoctonia solani, and Fusarium proliferatum. However, the inhibition of Fusarium oxysporum. f. sp cucumerinum decreased significantly in the later stages. This study had detected the purification process and antifungal activity on five fungi of the pink pigment of Erwinia persicina Cp2. It lays a theoretical and practical foundation for the production of related biological agents.

This study concentrates on the isolation of bio colour producing bacteria from goat droppings and application of its colour pigment in the textile dyeing process. The isolated strain is subjected to biochemical as well as molecular characterization and is identified as Pseudomonas aeruginosa using thin layer chromatography. An optimum condition for production of pigment 'Pyocyanin (blue-green)' has been studied by one-factor at a time approach. The pigment (Pyocyanin) is extracted using chloroform, and 0.2N hydrochloric acid. The application of this extracted bio color as coloring agent on polyester fabric has also been studied, and it is found that the color retained on the fabric is yellow, which is different from the extracted pigment colour. Color quality evaluation of dyed polyester fabric has been performed with references to international standard protocols. The color producing is found to be 1-hydroxyphenazine, obtained by the hydrolysis of Pyocyanin at high temperature (130°C). This 1-hydroxyphenazine imparts the yellow shade to polyester fabric on dyeing. [ABSTRACT FROM AUTHOR]

A pink pigment-producing bacterial strain was isolated from wastewater and identified as Paenibacillus sp. BPW19. The motile bacterial strain was Gram-positive, acid fermenting, glucose, sucrose utilizing and rod-shaped with an average cell length of 1.55 μm as studied under the Environmental Scanning Electron Microscope. Even though being psychrotolerant, the cell growth condition of BPW19 was optimized as 25 ºC along with pH 8, and 2.25% inoculum concentration considering the operational ease of the production. Sonication assisted solvent extraction produced 5.41% crude pigment which showed zones of exclusion against gram-negative strains Escherichia coli DH5α, Enterobacter sp. EtK3, and Klebsiella sp. SHC1. Gas Chromatography-Mass Spectrometry analysis of the crude pigment exhibited the dominant presence of major compounds as dotriacontane; 3,7 dimethyl 7 octanal; 1-eicosene and erucic acid. While column chromatography (ethanol:chloroform in 1:4 (v/v) ratio) purified pigment was identified as erucic acid using Nuclear Magnetic Resonance with a net yield of 3.06%.

Bacterial pigments are the unique and sustainable source of bioactive colour compounds used in cosmetics, food, textiles, printing and pharmaceutical products. Here, we report the pigment-producing isolates and their biological activities that could be benefited for different industries including cosmeceuticals. In this study, a total of 19 pigment-producing bacteria were isolated and purified from collected soil and water samples. The colour production ability of purified bacteria was observed up to 5 transfers. Of the 19 isolates, two isolates lost colour production ability in subsequent transfers. Crude pigments extracted from the remaining 17 isolates showed sunscreen activity in the range of 0.4–8.34. However, only 6 of them showed significant antibacterial and antioxidant activities. In the media optimization experiment, these 6 bacteria showed optimum growth in neutral to alkaline pH, while optimum temperatures for growth were different for different bacteria. One isolate produces the promising pigment, out of all six potential pigments. It is stable up to 5 transfers, having antioxidant and antibacterial activity with Sun protective activity; the strain was identified using 16srRNA gene sequencing and obtained accession number as MK770403 (probable strain is Staphylococcus xylosus) from National Center for Biotechnology Information (NCBI) database. The results of this study suggested that these bioactive pigments can further be developed and used as antibacterial, antioxidant and sun-protective ingredients in cosmeceuticals. [ABSTRACT FROM AUTHOR]

Pigments synthesised by Chryseobacterium sp. kr6 growing on feather waste were extracted and characterised. The pigment extract was characterised by KOH test, UV–vis, CIELAB colour system, HPLC-DAD-MS, FTIR and its antioxidant capacity was evaluated. A positive bathochromic shift was observed when kr6 colonies or pigment extracts were subjected to alkaline solution (20% KOH) and a λmax at 450 nm was detected for acetone extracts, although no typical fine structure of carotenoids was detected in the electomagnetic spectra. The HPLC profile of the extracted pigment showed that the compound has three different peaks with λmax near 450 nm. The FTIR analysis shows some principal functional groups from a flexirubin-like molecule. The pigmented compound also presents antioxidant activity evaluated by the scavenging of the ABTS radical. [ABSTRACT FROM AUTHOR]

In the present study, crude bacterial extract containing violacein is investigated for the preparation of antimicrobial polyamide fabrics. The optimal culture conditions of Janthinobacterium lividum (JL) for maximum biomass and violacein production were found to be 25°C, pH 7.0, while the addition of ampicillin of 0.2 mg mL-1 in the small scale increased violacein production 1.3-fold. In scale-up trials, the addition of 1% (v/v) glycerol in a fed-batch bioreactor, resulted in fivefold extracted crude violacein increase with final concentration of 1.828 g L-1. Polyamide 6.6 fabrics were dyed following three different processes; through simultaneous fermentation and dyeing (SFD), by incubating the fabric in the sonicated bacterial culture after fermentation and by using cell-free extract containing violacein. Maximum color change (ΔE) and color strength (K/S) obtained for SFD fabrics were 74.81 and 22.01, respectively, while no alteration of fastness and staining of dye at acid and alkaline perspiration or at water was indicated. The dyed fabrics presented significant antifungal activity against Candida albicans, C. parapsilosis, and C. krusei, as well as antibacterial properties against Escherichia coli, Staphylococcus aureus, and the S. aureus MRSA. We have shown that J. lividum cultures can be successfully used for violacein production and for simultaneous dying of fabrics resulting in dyed fabrics with antimicrobial properties without utilization of organic solvents.

The interest in and demand for natural dyes has increased significantly in recent years; however, very few natural blue dyes are commercially available, because blue colored compounds in nature are relatively rare. In this study, a blue pigment-producing bacteria from Lake Chungará (Atacama Desert, Chile) was isolated, and its blue pigment was purified and chemically characterized. The pigment-producing strain was identified as Pseudarthrobacter sp. by 16S rRNA gene sequencing. The pigment was separated from the filtered culture medium by column chromatography/solid-phase extraction using different resins (ionic exchange, C-18, size exclusion). The strain produced up to 2.5 g L−1 of blue pigment, which was very soluble in water, partially soluble in methanol and insoluble in other organic solvents. The pigment was analyzed and characterized by analytical HPLC, UV-Vis, FT-IR, and H-NMR, and purified by semi-preparative HPLC. The pigment was non-toxic to brine shrimp (LD50 > 2.3 g L−1) and was stable at pH 6-10 at temperatures below 60 °C. HPLC analysis shows that the pigment is composed of four major blue fractions. The physicochemical properties and structural analysis demonstrate that this pigment belongs to the indochrome isomers, whose properties have yet to have been characterized. The high solubility in water, good stability in neutral and basic pH, and negligible toxicity of the blue pigment make it a good candidate suitable for several industrial and possibly some food applications. [ABSTRACT FROM AUTHOR]

In the present study, crude bacterial extract containing violacein is investigated for the preparation of antimicrobial polyamide fabrics. The optimal culture conditions of Janthinobacterium lividum (JL) for maximum biomass and violacein production were found to be 25°C, pH 7.0, while the addition of ampicillin of 0.2 mg mL-1 in the small scale increased violacein production 1.3-fold. In scale-up trials, the addition of 1% (v/v) glycerol in a fed-batch bioreactor, resulted in fivefold extracted crude violacein increase with final concentration of 1.828 g L-1. Polyamide 6.6 fabrics were dyed following three different processes; through simultaneous fermentation and dyeing (SFD), by incubating the fabric in the sonicated bacterial culture after fermentation and by using cell-free extract containing violacein. Maximum color change (ΔE) and color strength (K/S) obtained for SFD fabrics were 74.81 and 22.01, respectively, while no alteration of fastness and staining of dye at acid and alkaline perspiration or at water was indicated. The dyed fabrics presented significant antifungal activity against Candida albicans, C. parapsilosis, and C. krusei, as well as antibacterial properties against Escherichia coli, Staphylococcus aureus, and the S. aureus MRSA. We have shown that J. lividum cultures can be successfully used for violacein production and for simultaneous dying of fabrics resulting in dyed fabrics with antimicrobial properties without utilization of organic solvents. [ABSTRACT FROM AUTHOR]

Background: The increment of resistant strains to commonly used antibiotics in clinical practices places in evidence the urgent need to search for new compounds with antibacterial activity. The adaptations that Antarctic microorganisms have developed, due to the extreme environment that they inhabit, promote them as a potential new source of active compounds for the control of microorganisms causing infections associated with health care. The aim of this study was to evaluate the antibacterial activity of an ethanol extract of the Antarctic bacterium Janthinobacterium sp., strain SMN 33.6, against nosocomial multi-resistant Gram-negative bacteria. Results: Inhibitory activity against human Gram-negative bacterial pathogens, with concentrations that varied between 0.5 and 16 μg ml-1, was demonstrated. Conclusions: The ethanolic extract of Janthinobacterium sp. SMN 33.6 possesses antibacterial activity against a chromosomal AmpC beta-lactamase-producing strain of Serratia marcescens, an extended-spectrum beta-lactamase-producing Escherichia coli and also against carbapenemase-producing strains of Acinetobacter baumannii and Pseudomonas aeruginosa. This becomes a potential and interesting biotechnological tool for the control of bacteria with multi-resistance to commonly used antibiotics.

Renewed demand for incorporation of natural dyes (bio-colorants) in textile industry could be met through biotechnological production of bacterial pigments. Two new Streptomyces strains (NP2 and NP4) were isolated for the remarkable ability to produce diffusible deep blue and deep red pigment into fermentation medium. Crude mycelial extracts of both strains were used as bio-colorants in conventional textile dyeing procedures avoiding downstream purification procedures. The yields of bio-colorants obtained in this way were 62 and 84 mg per g of mycelia for Streptomyces sp. NP2 and Streptomyces sp. NP4, respectively. Through nuclear magnetic resonance analysis of crude extracts before and after dyeing procedures, it was shown that both extracts contained prodigiosin-like family of compounds that exhibited different dyeing capabilities towards different textile fibers. Polyamide and acrylic fibers were colored to the deepest shade, polyester and triacetate fibers to a noticeable, but much lower shade depth, while cotton and cellulosic fibers stained weakly. These results confirmed that crude bacterial extracts had the characteristics similar to those of ionic and disperse dyes, which was consistent with the identified polypyrrolic prodigiosin-like structures. [ABSTRACT FROM AUTHOR]

The growing demand to fulfill the needs of present-day medicine in terms of novel effective molecules has lead to reexamining some of the old and known bacterial secondary metabolites. Bacterial prodigiosins (prodiginines) have a long history of being re markable multipurpose compounds, best examined for their anticancer and antimalarial activities. Production of prodigiosin in the most common producer strain Serratia marcescens has been described in great detail. However, few reports have discussed the ecophysiological roles of these molecules in the producing strains, as well as their antibiotic and UV-protective properties. This review describes recent advances in the production process, biosynthesis, properties, and applications of bacterial prodigiosins. Special emphasis is put on undecylprodigiosin which has generally been a less studied member of the prodigiosin family. In addition, it has been suggested that proteins involved in undecylprodigiosin synthesis, RedG and RedH, could be a useful addition to the biocatalytic toolbox being able to mediate regio- and stereoselective oxidative cyclization. Judging by the number of recent references (216 for the 2007-2013 period), it has become clear that undecylprodigiosin and other bacterial prodigiosins still hold surprises in terms of valuable properties and applicative potential to medical and other industrial fields and that they still deserve continuing research curiosity. [ABSTRACT FROM AUTHOR]

We report an overlooked source of artifacts for clinical specimens, where unexpected and normally negligible contaminants can skew the interpretation of results. During an ongoing study of bone fragments from diabetic osteomyelitis, strong Raman signatures were found, which did not correspond with normal bone mineral or matrix. In a bone biopsy from the calcaneus of a patient affected by diabetic osteomyelitis, Raman microspectroscopic analysis revealed regions with both abnormal mineral and degraded collagen in addition to normal bone. Additional bands indicated a pathological material. Stenotrophomonas maltophilia was identified in the wound culture by independent microbiologic examination. We initially assigned the unusual bands to xanthomonadin, a bacterial pigment from S. maltophilia. However, the same bands were also found more than a year later on a second specimen that had been noticeably contaminated with pathology marking dye. Drop deposition/Raman spectroscopy of commonly used pathology dyes revealed that a blue tissue-marking dye was responsible for the unusual bands in both specimens, even in the first specimen where there was no visible evidence of contamination. [ABSTRACT FROM AUTHOR]

In this study, we describe the antimycobacterial activity of two pigments, violacein, a purple violet pigment from Janthinobacterium sp. Ant5-2 (J-PVP), and flexirubin, a yellow-orange pigment from Flavobacterium sp. Ant342 (F-YOP). These pigments were isolated from bacterial strains found in the land-locked freshwater lakes of Schirmacher Oasis, East Antarctica. The minimum inhibitory concentrations (MICs) of these pigments for avirulent and virulent mycobacteria were determined by the microplate Alamar Blue Assay (MABA) and Nitrate Reductase Assay (NRA). Results indicated that the MICs of J-PVP and F-YOP were 8.6 and 3.6 μg/ml for avirulent Mycobacterium smegmatis mc155; 5 and 2.6 μg/ml for avirulent Mycobacterium tuberculosis mc6230; and 34.4 and 10.8 μg/ml for virulent M. tuberculosis HRv, respectively. J-PVP exhibited a ~15 times lower MIC for Mycobacterium sp. than previously reported for violacein pigment from Chromobacterium violaceum, while the antimycobacterial effect of F-YOP remains undocumented. Our results indicate these pigments isolated from Antarctic bacteria might be valuable lead compounds for new antimycobacterial drugs used for chemotherapy of tuberculosis. [ABSTRACT FROM AUTHOR]

Enterobacter sakazakii is considered an opportunistic foodborne pathogen that is characterized by formation of yellow-pigmented colonies. Because of the lack of basic knowledge about Enterobacter sakazakii genetics, the BAC approach and the heterologous expression of the pigment in Escherichia coli were used to elucidate the molecular structure of the genes responsible for pigment production in Enterobacter sakazakii strain ES5. Sequencing and annotation of a 33.025 bp fragment revealed seven ORFs that could be assigned to the carotenoid biosynthesis pathway. The gene cluster had the organization crtE- idi- XYIBZ, with the crtE-idi-XYIB genes putatively transcribed as an operon and the crtZ gene transcribed in the opposite orientation. The carotenogenic nature of the pigment of Enterobacter sakazakii wt was ascertained by in situ analysis using visible microspectroscopy and resonance Raman microspectroscopy. [ABSTRACT FROM AUTHOR]

• Pigmented P. piscicida inhibits uniform corrosion via biomineralization. • Pigmented P. piscicida induces pitting corrosion under the biomineralzied film. • Bacterial pigments act as an electron acceptor or mediator in the process of corrosion. Employing microorganisms to protect metal surfaces requires significant investigation before they can be translated to field applications. Here, a pigmented Pseudoalteromonas piscicida strain inhibited uniform corrosion but accelerated pitting corrosion of steel materials. The corrosion protection was attributed to a compact biomineralized film composed of calcite and EPSs. However, pitting corrosion still occurred under the film due to pigment secreted by the P. piscicida. This was further corroborated by immersing steel in an abiotic pigment medium. This study introduces a new perspective on the dual roles of bacterial pigments and biomineralization in corrosion. [ABSTRACT FROM AUTHOR]