Pigmented Bacteria Research Articles

Identification of pigmented extremophilic bacteria from mangrove soil with antibiofilm activity on food pathogens

Mangrove ecosystems and associated microorganisms are always a source of curiosity for researchers. Pigment producing bacteria were isolated from the mangrove soil in Kadamakkudi, Cochin, Kerala. The bacteria were biochemically identified and by 16 S rRNA gene sequence. The pigments extracted had been tested for antibiofilm activity against food pathogens Pseudomonas aeruginosa (NCIM 2863), Klebsiella pneumoniae (NCIM 5215), and Escherichia coli (NCIM 2343). Antibiofilm activity was further confirmed by fluorescent and scanning electron microscopy. Six yellow-orange pigmented bacteria (KDR2, KDR3, KDR7, KDR8, KDR14 and KDS1) were isolated. KDR2 was identified as Cellulosimicrobium funkei, KDR7 and KDS1 as Cytobacillus depressus, KDR8 as Bacillus aquimaris, and KDR3 and KDR14 as Halobacillus sp. All of these organisms are known to be extremophiles. The UV-Visible absorption spectrum of all the pigments ranged from 400 nm to 550 nm with different absorbance maxima. All the pigments showed antibiofilm activity against the food pathogens tested.

Antibacterial activity of pigment extracted from bacteria isolated from soil samples

The purpose of this study was to evaluate antibacterial activity of pigment extracted from bacteria, isolated from soil samples. During the study, 20 soil samples were collected from different areas (forest, agriculture fields, river sides and dumping sites) of Kathmandu and Lalitpur districts which were processed for isolation of pigment producing bacteria by spread plate technique. The pigmented bacterial isolates were identified and enriched in nutrient broth. Then, pigment was extracted in 95% methanol as solvent, which was further characterized using UV-Vis Spectrophotometric and TLC analysis. The obtained crude pigment extract was processed to carry out the antimicrobial susceptibility assay using agar well diffusion method. Out of 13 total pigmented bacteria isolates, four different colored pigmented bacterial isolates (S4O, S11Y, S14P and S17G) which produced efficient pigment on nutrient agar were chosen and they were further processed. Among these isolates, S4O was identified as Staphylococcus aureus, S11Y was identified as Micrococcus luteus, S14P was identified as Micrococcus roseus and S17G was identified as Pseudomonas aeruginosa respectively. On characterization using UV-Vis Spectrophotometric and TLC analysis, the pigment extracted from isolates S4O, S11Y and S14P were found to be Carotenoids and from isolate S17G was found to be Pyocyanin in nature. The maximum antibacterial activity was shown against Staphylococcus aureus from all the four pigments extracts. The green color pigment extract from isolate S17G was found to be most effective against all the Gram-positive and Gram-negative test bacteria. This study suggests that these pigment extracts from pigmented bacteria may have beneficial antibacterial roles that can be exploited in controlling unwanted bacterial growth.

Black-Pigmented Marine Pseudomonas aeruginosa Exhibiting Anti-Bacterial Activity against Multidrug-Resistant (MDR) Wound Infection Bacteria

The urgency of multidrug-resistant (MDR) bacterial infections in wounds is a significant concern due to the high prevalence of MDR in healthcare settings. Black pigmented marine bacteria, strain PS1C, were isolated from marine sediment on Awur Beach Jepara, Central Java, Indonesia, and cultured in the laboratory. The aim of this research includes molecular identification of strain PS1C, extracting black pigment from strain PS1C, isolation of MDR bacteria from wounds, and evaluating the antibacterial activity of black pigment from strain PS1C against MDR bacteria isolates of wound infections. We examined the 16S rRNA gene sequences strain PS1C to identify the species. Then, the black pigment from PS1C was extracted using methanol: acetone (7:3) solvent. Antibacterial activity was evaluated against MDR bacteria from wounds with the microdilution method. A black-pigmented bacterium was isolated and identified as Pseudomonas aeruginosa PS1C. We found that the black pigment from P. aeruginosa PS1C can be developed as an antibacterial agent against the MDR bacterial isolate of wounds with MIC and MBC values of 6.25-12.5 mg/ml and 6.25-25 mg/ml, respectively. In conclusion, the study's findings highlight the potential of the extract of black pigment from P. aeruginosa PS1C as an antibacterial agent against wound-causing MDR bacteria and reinforce previous research into P. aeruginosa can be isolated from marine sources. Additional in vivo investigations and the identification of the antibacterial activity's mode of action are required.

Pengzhenrongella phosphoraccumulans sp. nov., isolated from high Arctic glacial till, and emended description of the genus Pengzhenrongella.

A yellow pigmented, Gram-stain-positive, motile, facultatively anaerobic and irregular rod-shaped bacteria (strain M0-14T) was isolated from a till sample collected from the foreland of a high Arctic glacier near the settlement of Ny-Ålesund in the Svalbard Archipelago, Norway. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that M0-14T formed a lineage within the family Cellulomonadaceae, suborder Micrococcineae. M0-14T represented a novel member of the genus Pengzhenrongella and had highest 16S rRNA gene sequence similarity to Pengzhenrongella sicca LRZ-2T (97.3 %). Growth occurred at 4-25 °C (optimum 4-18 °C), at pH 6.0-9.0 (optimum pH 7.0), and in the presence of 0-5 % (w/v) NaCl. The predominant menaquinone was MK-9(H4) and the major fatty acids were anteiso-C15 : 0, C16 : 0 and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c). The major polar lipids were phosphatidylglycerol, phosphatidylinositol mannosides, phosphatidylinositol, one undefined phospholipid and five undefined phosphoglycolipids. The cell-wall diamino acid was l-ornithine whereas rhamnose and mannose were the cell-wall sugars. Polyphosphate particles were found inside the cells of M0-14T. Polyphosphate kinase and polyphosphate-dependent glucokinase genes were detected during genomic sequencing of M0-14. In addition, the complete pstSCAB gene cluster and phnCDE synthesis genes, which are important for the uptake and transport of phosphorus in cells, were annotated in the genomic data. According to the genomic data, M0-14T has a metabolic pathway related to phosphorus accumulation. The DNA G+C content of the genomic DNA was 70.8 %. On the basis of its phylogenetic relationship, phenotypic properties and chemotaxonomic distinctiveness, strain M0-14T represents a novel species of the genus Pengzhenrongella, for which the name Pengzhenrongella phosphoraccumulans sp. nov. is proposed. The type strain is M0-14T (= CCTCC AB 2012967T = NRRL B-59105T).

Screening for pigment production and characterization of pigment profile and photostability in cold-adapted Antarctic bacteria using FT-Raman spectroscopy

Microbial pigments can replace synthetic organic pigments which often produced in unsustainable way and can be toxic. Therefore, search for new pigment producing microorganisms is of high interest for industry. In this study, a screening and characterization of pigment profile and photostability in seventy-four newly isolated Antarctic bacteria using Fourier-transform (FT) Raman spectroscopy and HPLC-MS was performed. Screening of the bacterial biomass by FT-Raman identified thirty-seven bacterial strains from the genera Agrococcus, Arthrobacter, Brachybacterium, Cryobacterium, Leifsonia, Micrococcus, Paeniglutamicibacter, Rhodococcus, Salinibacterium and Flavobacterium as having relatively high pigment content. The impact of growth temperature on the pigment production in the studied Antarctic bacteria was species - specific, while blue light exposure triggered pigment production in majority of the studied bacteria. HPLC-MS analysis of a biomass of a set of ten pigmented Antarctic bacteria identified eighteen different carotenoids and precursors. FT-Raman spectroscopy showed to be suitable for both, semi-qualitative library-independent identification of pigment producing bacteria and determination of pigment profile using spectral library of reference pigment standards. This study provides valuable insights into the pigment production capabilities of Antarctic bacteria and highlighting the potential of FT-Raman spectroscopy for characterizing microbial pigments.

Production, characterization and in vitro biological activities of crude pigment from endophytic Micrococcus luteus associated with Avicennia marina.

Due to their non-toxic and non-carcinogenic nature, biopigments have a phenomenal benefit over synthetic pigments, making them a desirable source for human utilization and a potential alternative to traditional synthetic pigments that are hazardous to the environment and public health. Endosymbiotic interactions between mangrove plants and bacteria could provide an alternate source for the synthesis of unique compounds with potent biomedical applications. Pigmented endophytic bacteria were screened from the explants of Avicennia marina, a mangrove plant, and identified as Micrococcus luteus by molecular characterization. The intracellular pigment was successfully extracted using the sonication-assisted solvent extraction method, and screening factors impacting the pigmentation bioprocess were determined using a one-factor-at-a-time approach. The endophyte produced yellow pigment in the liquid medium, with the maximum growth and pigment production recorded in nutrient broth at 37℃ and pH 7 after 96h of incubation, while the maximum accumulation of pigment was observed in the media supplemented with glucose and tryptone as carbon and nitrogen sources, respectively. The extracted crude pigment was further characterized by ultraviolet, followed by Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. The obtained crude pigment has been evaluated for its antioxidant and anticancer activity by various assays, such as DPPH radical scavenging activity, FRAP assay, superoxide anion and nitric oxide radical scavenging, metal chelating activity, phosphomolybdenum assay, and MTT assay, respectively, at varying concentrations. The results of our study revealed that the yellow pigment produced by the endophyte showed significant dose-dependent antioxidant and anticancer activity.

Alteriqipengyuania flavescens sp. nov., isolated from Pearl River Estuary sediment.

Two Gram-stain-negative, aerobic, rod-shaped, non-motile and golden yellow pigmented bacteria, designated as SCSIO 75105T and SCSIO 75732, were isolated from sediment in the Pearl River Estuary, Guangdong Province, PR China. Cells were positive for catalase and oxidase. Growth occurred at 10-37 °C (optimum, 28 °C), pH 6.0-10.0 (optimum, pH 7.0) and 0-5.0 % (w/v) NaCl (optimum, 2.0-3.0 %). The 16S rRNA gene analysis indicated that these two isolates shared a similarity of 100 % each other. The 16S rRNA gene sequence analysis indicated that these two isolates showed highest similarity to Altererythrobacter ishigakiensis CGMCC 1.14979T (97.3 %). However, a phylogenetic tree based on 288 orthologous clusters indicated that these two isolates were closely related to Alteriqipengyuania halimionae CPA5T. The average nucleotide identity, average amino acid identity, digital DNA-DNA hybridization and evolutionary distance values between the two isolates and Alteriqipengyuania halimionae CPA5T were 73.7-74.0 %, 65.2 %, 19.5 % and 0.24, respectively. The genomic DNA G+C content of both isolates was 65.2 mol%. The major cellular fatty acids were C18 : 1 ω7c, C17 : 1 ω6c and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), and Q-10 was the respiratory quinone. The polar lipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, sphingoglycolipid and one unidentified glycolipid. On the basis of the results of phenotypic, physiological, chemotaxonomic and genotypic characterization, strains SCSIO 75105T and SCSIO 75732 are considered to represent a novel species in the genus Alteriqipengyuania, for which the name Alteriqipengyuania flavescens sp. nov. is proposed. The type strain is SCSIO 75105T (=KCTC 92502T=MCCC 1K07993T).

Paenimyroides aestuarii gen. nov. sp. nov., a novel bacterium isolated from sediment in the Pearl River Estuary and reclassification of five Flavobacterium and four Myroides species.

An aerobic, Gram-negative, non-motile, yellow-to-orange pigmented and round bacterium, designated strain SCSIO 72103T, was isolated from sediment collected in the Pearl River Estuary, Guangdong Province, PR China and subjected to a polyphasic taxonomic study. Growth occurred at 20-37 °C (optimum, 28 °C), pH 6-8 (optimum, pH 7) and with 1-5.5% NaCl (optimum, 1-3 %). Comparative 16S rRNA gene analysis indicated that strain SCSIO 72103T had the highest similarities to Flavobacterium baculatum SNL9T (94.7 %) and Myroides aquimaris SW105T (94.2 %). Phylogenetic analysis based 16S rRNA gene sequences showed that strain SCSIO 72103T formed a single clade with M. aquimaris SW105T. Strain SCSIO 72103T contained iso-C15 : 0 as the major fatty acid and the predominant respiratory quinone was menaquinone MK-6. These characteristics are consistent with those of F. baculatum SNL9T and M. aquimaris SW105T. Phosphatidylethanolamine, most notably, unidentified aminolipid and unidentified aminophospholipid were major polar lipids. Strain SCSIO 72103T had a single circular chromosome of 2.96 Mb with a DNA G+C content of 35.1 mol%. The average nucleotide identity, average amino acid identity (AAI) and digital DNA-DNA hybridization values showed that the pairwise similarities between SCSIO 72103T and the type strains of F. baculatum SNL9T and M. aquimaris SW105T were 78.5-80.5 %, 79.0-81.4 % and 22.7-22.8 %, respectively. The AAI values between species in this clade and the type species of Flavobacterium and Myroides were below the 65 % threshold, indicating that these species belong to a novel genus. On the basis of phylogenetic, physiological and chemotaxonomic characteristics, strain SCSIO 72103T represents a new species of a novel genus, for which the name Paenimyroides aestuarii gen. nov. sp. nov. is proposed. The type strain is SCSIO 72103T (=KCTC 92043T=MCCC 1K06659T). It is also proposed that nine known species in the genera Flavobacterium and Myroides are reclassified as Paenimyroides species.

Diversity and Distribution Characteristics of Culturable Bacteria in Burqin Glacier No. 18, Altay Mountains, China

Ecosystems away from human disturbance provide an ideal paradigm for microbial ecology research. The Burqin glacier No. 18 in the Chinese Altay Mountains is such an ecosystem; however, there are no prior studies on the microbiology in the area. Here, we isolated 902 bacterial strains on the Burqin glacier No. 18 to determine the diversity and distribution characteristics of microorganisms. Isolated strains belonged to six phyla (in the order of dominance: Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Deinococcus-Thermus) and 90 genera. Our results also demonstrated the presence of a high proportion of potential new species (43%) in the Burqin glacier No. 18, and 67% of the potential new species were isolated at 25 °C. Species diversity varied among habitats, with the lowest diversity in surface ice and the highest diversity in the soil farthest from the glacier terminus. The pigmented colonies made up 52.7% of all isolates, with yellow-colored colonies being the most abundant (18.8%). This study indicates that the Burqin glacier No. 18 hosts rich bacterial strain diversity, and may represent a significant potential source of new functional and pigmented bacteria for the development of critical pharmaceuticals.

Glaciochemistry and Pigment Producing Ability of Bacteria from the Roof of the World, the Glaciers of Karakoram, Pakistan

The Karakoram Mountain Range (KMR) is one of the largest mountain ranges in the world, with ∼37% of its area glaciated. Glaciers harbor various microbes, including bacteria exposed to various extreme conditions. To thrive under these conditions, bacteria adopt various strategies, one of the most important being the production of pigments. Here, we present the geochemistry of ice, sediment and meltwaters sampled from Ghulmet, Ghulkin and Hopar glaciers of the Karakoram Range, Pakistan. In addition, we report the first information on the diversity of pigmented bacteria evaluated using a culture-dependent method and determined pigment production response of selected bacterial species to different temperatures. Geochemical analyses revealed Ca2+ and SO4 2– to be the most abundant cation and anion species across all glacial samples. Total organic carbon (TOC), total nitrogen (T.N.) and total phosphorus (T.P.) were found in the sediments of all glaciers studied in current research. Bacterial species were capable of producing a variety of different pigments, including alloxanthin, astaxanthin, bacterioruberin, β-carotene, 19'-hexanoyloxyfucoxanthin, peridinin, violacein and zeaxanthin. Culturable bacterial diversity based on two molecular biomarkers, 16S rRNA and rpoB gene, revealed total of 82 bacterial strains representing 25 genera across all glacial samples. This study provides the first characterization of glacier-associated, pigment-producing bacterial communities from the KMR. Findings are important for consideration of alternative sources of conventional pigment production in industrial fields.

Antibacterial Activity of Carotenoid Pigments Produced by Heterotrophic Bacteria from Seawater in Krakal Coastal Area, Yogyakarta, Indonesia

Investigating natural pigments resulting from marine bacterial secondary metabolites is important because of their broad benefits in the food, pharmaceutical, cosmetic, and textile industries. In this study, 52 isolates of pigmented bacteria were isolated from seawater in the Krakal coastal area, Yogyakarta, Indonesia. Seven bacterial isolates showed high pigment stability. Profiling of pigment extracts using a mixture of acetone and methanol with UV–Vis spectrophotometric reading showed that the compounds produced were carotenoids. The highest total carotenoid content with UV–Vis spectrophotometric reading at 480 nm was produced by the Kral-3 isolate (1800 mg/g), followed by Kral-15 (1698.9 mg/g) and Kral-25 (797.2 mg/g) isolates. Analysis of the antibacterial activity of the carotenoid extracts of Kral-3, Kral-15, and Kral-25 isolates using the agar well diffusion method revealed a very strong inhibition score against Escherichia coli. In addition, the carotenoid extract of the Kral-3 isolate showed a strong inhibition score against Staphylococcus aureus, whereas the Kral-15 and Kral-25 isolates showed moderate inhibition scores. Based on the 16S rRNA gene analysis, the Kral-3, Kral-15, and Kral-25 isolates were identified as Kocuria rhizophilla, Calidifontibacter sp., and Rhodococcus ruber, respectively. Based on the findings, the novel bacterial strains are a potential bioresource for the commercial production of natural carotenoids.

Impact of foliar fertilization of nutrients and biofertilizer on the growth and yield of hybrid cotton (Gossypium hirsutum L.)

The newly released high yielding cotton cultivars are higher boll retention rate than conventional cultivars that have higher overall nutrient demand during the flowering and boll development stages. Therefore, this field experiment was conducted at during summer, 2020 at Annamalai University experimental farm, Department of Agronomy, Faculty of Agriculture, Annamalai Nagar, Tamil Nadu, India, 608 002 to ascertain the impact of foliar application of essential nutrients and biofertilizers on growth and yield of cotton. The experiment was laid out in randomized block design with twelve treatments of foliar application macro and micro-nutrients with and without Pink pigmented facultative methylotrophic bacteria (PPFM) and replicated thrice. Foliar application of macro, micronutrients and PPFM registered the increased values of growth characters, yield attributes and yield of hybrid cotton. Among the foliar application practice tested, foliar application of 2% urea + 1% PPFM at flowering and boll development stages significantly resulted in the enhances values of growth characters viz., plant height (157.40 cm), Dry matter production (6003 kg/ha), number of monopodial branches (3.28/plant), growth analysis like Leaf area index (4.30), Crop growth rate (7.01 g/m2/day) and Relative growth rate (0.0144 g/g/day), yield attributes viz., number of sympodial branches (21.77/plant), number of squares (83.77/plant), number of bolls (45.04/plant), boll weight (5.58 g) and seed cotton yield (3185 kg/ha). This was statistically on par with the foliar application of 2% MgSO4 + 1% PPFM at flowering and boll development stages. The lower values of growth characters, yield attributes and yield were recorded under water spray treatment. Based on the results of field investigation it can be concluded that foliar application of 2% urea + 1% PPFM at flowering and boll development stages can possibly enhance the growth and yield of hybrid cotton grown under dryland condition.

Humibacter ginsenosidimutans sp. nov., with ginsenoside-converting activity isolated from activated sludge.

A novel Gram-stain-positive, thin rod-shaped, non-motile, aerobic and creamy-white pigmented bacterium (designated strain WJ7-1T) was isolated from activated sludge sampled in Suwon, Republic of Korea. 16S rRNA gene sequence analysis indicated that the isolate belongs to the genus Humibacter, family Microbacteriaceae, with a sequence similarity of 97.9 % to its nearest neighbour Humibacter albus KACC 20986T. Strain WJ7-1T contained menaquinone (MK)-10 (16.0 %), 11 (48.5 %) and 12 (35.5 %) as major respiratory quinones. The predominant cellular fatty acids (>15 %) were anteiso-C17 : 0, iso-C16 : 0 and anteiso-C15 : 0. The peptidoglycan of strain WJ7-1T contained the diagnostic diamino acid ornithine and 2,4-diaminobutyric acid alanine. Alanine, glutamic acid and glycine were also present in the cell wall. The characteristic whole-cell sugars present were glucose, galactose, xylose and rhamnose. The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, an unidentified glycolipid and two unidentified phospholipids. Strain WJ7-1T possessed ginsenoside-converting (β-glucosidase) activity, which enabled it to transform ginsenoside protopanaxadiol-type Rb1 (one of the dominant active components of ginseng) to compound K. The genome size of strain WJ7-1T has 4.2 Mbp and the G+C content is 68.3 mol%. Average nucleotide identity, amino acid identity and digital DNA-DNA hybridization values between strain WJ7-1T and the closely related strain were 79.8, 36.1 and 23.5 %, respectively, indicating that strain WJ7-1T represents a novel species of the genus Humibacter. Strain WJ7-1T could be distinguished from the other members of the genus Humibacter by a number of chemotaxonomic and phenotypic characteristics. Based on polyphasic taxonomic analysis, strain WJ7-1T (=KACC 19729T=LMG 30802T) represents a novel species within the genus Humibacter, for which the name Humibacter ginsenosidimutans sp. nov. is proposed.

Chromogenicity of aerobic spore-forming bacteria of the Bacillaceae family isolated from different ecological niches and physiographic zones.

To determine the distribution patterns of pigmented bacteria of the Bacilaceae family in different physiographic zones and ecological niches, we recovered 787 isolates from 185 environmental samples (including the areas with radiation pollution). Among the strains obtained, 149 pigmented representatives were detected, which synthesized intracellular and extracellular pigments of yellow, red, pink, and dark colors. In compliance with physiological, biochemical, and chemotaxonomic features, the isolates were identified as 7 species of the Bacilaceae family. We demonstrated that the ability to synthesize pigments significantly depended on the culture medium composition. According to the color of the colonies, the absorption spectra of pigment extracts, their physicochemical properties, and the implementation of several qualitative tests, the pigmented isolates were divided into ten groups. The relative number of pigmented strains in the physiographic zone was consistent with the total level of solar radiation for the year. Most pigmented members of the Bacillaceae family were recovered from deserts and semi-deserts, and fewest of them originated from mixed forests. We show that among the studied ecological niches, pigmented strains were most often isolated from the phyllosphere and aquatic environment and least often from soils. However, the isolates from soils and aquatic environments exhibited a greater diversity of pigmentation, and a lesser variety of colored strains was obtained from the phyllosphere and the gastrointestinal tract of animals. We established that the quantitative and qualitative composition of pigmented isolates from the areas with radiation contamination differed significantly from those coming from the natural radiation background.

A study on extraction and characterization of natural red pigment from a soil isolate Serratia marcescens CN14

Natural pigments are a brilliant alternative to artificial ones used for formulations in food, cosmetics and textile industries. Microorganisms, in particular, bacteria are an essentially obliging source for the production and extraction of biologically safe pigments. Thus, this study was aimed at isolating pigmented bacteria and extracting the pigment, characterizing it thereafter. Red pigmented bacteria isolated from a soil sample from the agricultural field of VIT, Vellore was used for the present study. The maximum growth was attained at room temperature. The bacterium was isolated and incubated for pigment production. The pigment was obtained from the pellets extracted using acetone and the purified pigment was identified by spectral analysis, TLC, HPLC and GCMS. The red color pigment, prodigiosin is considered as a potential treatment due to the activities against pathogens, the ability to control cancer can be an immunosuppressive and anti-proliferative agent. This gram-negative bacterium was identified as a Serratia marcescens strain by 16S rRNA gene sequencing. The gene sequence was submitted to NCBI as Serratia marcescens CN14 with an accession number of MT007931.

Potential of pink pigmented methylotrophic bacteria on growth and physiology of cluster bean and soil microbial community

Methylotrophs are one of the prominent microbial community which are known for utilizing methanol as well as carbon sources from various plant metabolic activities and in turn facilitates the host plant growth by synthesizing phytohormones. A pot study was conducted to examine the bio-fertilizing potential of pink pigmented methylotrophic bacteria (PPFM) on cluster bean ( Cyamopsis tetragonolaba (L.) Taub and its impact on soil microbial communities . Foliar and soil application modes of treatment was employed for the study. Our results showed that isolated strain from Quisqualis indica leaf was identified as Methylobacterium tardum (strain IHBB) by 16s rRNA gene sequence and phylogenetic analysis confirmed its relationship with other Methylobacterium spp. Soil microbes such as bacterial population (9.25 CFU x 10- 6 /g), fungal population (70.05 CFU x 10 −3 /g) and microalgae (9.65 CFU x 10 −4 /g) were found to be enhanced in 3% of M. tardum (T2) when compared to T1, T3 and control. Soil application of M. tardum exhibited better response on growth, biochemical and yield parameters of cluster bean than foliar application . This study confirms that M. tardum could be a promising candidate as microbial inoculant for plant growth and development as well as a positive driver for enriching the soil microbial community. •Isolated strain from Quisqualis indica leaf was identified as Methylobacterium tardum (strain IHBB) by 16s rRNA gene sequence and phylogenetic analysis confirmed its relationship with other Methylobacterium spp. • Soil application of M. tardum exhibited better response on growth, biochemical and yield parameters of cluster bean than foliar application. • Soil microbes such as bacterial population, fungal population and microalgae were found to be enhanced in 3% of M. tardum (T2). • M. tardum could be a suitable candidate as microbial inoculant for plant growth and development has the potential of enriching the soil microbiota.

Chitinophaga chungangae sp. nov., isolated from a Korean grape garden and its potential to biosynthesize ginsenoside Rg2.

A ginsenoside Rg2-producing, Gram stain-negative, aerobic, catalase and oxidase-positive, rod-shaped, non-motile and orange pigmented novel bacterium designated strain MAH-28T was isolated from soil sample of a grape garden. Strain MAH-28T hydrolyzed aesculin, casein and DNA. Flexirubin-type pigments are present. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain MAH-28T formed a cluster within the genus Chitinophaga and the most close relatives were Chitinophaga alhagiae T22T (98.9% 16S rRNA gene sequence similarity), Chitinophaga humicola Ktm-2T (98.8%), Chitinophaga barathri YLT18T (98.3%) and Chitinophaga lutea ZY74T (97.4%). The novel strain MAH-28T has a draft genome size of 6,043,180bp (14 contigs), annotated with 4,863 protein-coding genes, 53 tRNA and 6 rRNA genes. The ANI and dDDH values between strain MAH-28T and the closely related type strains were in the range of 76.0-83.4% and 20.3-26.7%, respectively. The novel strain MAH-28T was able to synthesize ginsenoside Rg2 from major ginsenoside Re. The genome annotation revealed 152 carbohydrate genes which may involve with the synthesis of ginsenoside Rg2. The respiratory quinone of strain MAH-28T was MK-7 and the dominant cellular fatty acids were C15:0 iso, C16:1 ω5c and C17:0 iso 3-OH. The DNA G + C content of strain MAH-28T was 53.3mol%. Based on the phenotypic, chemotaxonomic and phylogenetic studies, strain MAH-28T represents a new member of genus Chitinophaga for which the name Chitinophaga chungangae sp. nov. is proposed with type strain MAH-28T (= KACC 19968T = CGMCC 1.16605T).

Characterization of communities in a microalgae-bacteria system treating domestic wastewater reveals dominance of phototrophic and pigmented bacteria

The consortia formed by microalgae and bacteria developed during semi-continuous operation of photobioreactors treating domestic wastewater was characterized by means of flow cytometry and DGGE techniques. While microalgae population was dominated by the inoculated wild strain Chlorella sorokiniana, the bacterial community included as activated sludge was totally replaced by microbial groups exhibiting adaptations to illuminated environments. The quantification conducted by flow cytometry evidenced bacterial population displacement favoring pigmented and photoheterotrophic groups. This fact was correlated with DGGE analysis that showed the dominance of Rhodobacteraceae family during steady state conditions and disappearance of Rhizobiaceae family present in the inoculum. This particular bacterial community composition was related with the limited organic matter consumption detected in the experimental reactors, estimated in removal rates of 64.2 ± 4.8% of biodegradable chemical oxygen demand present in primary treated wastewater. In conclusion, the dominance of photoheterotroph and pigmented bacteria reduced the metabolic capability of the photobioreactor resulting in insufficient wastewater treatment with regard to discharge regulations.

Classification of a Violacein-Producing Psychrophilic Group of Isolates Associated with Freshwater in Antarctica and Description of Rugamonas violacea sp. nov.

ABSTRACTA group of 11 bacterial strains was isolated from streams and lakes located in a deglaciated northern part of James Ross Island, Antarctica. They were rod-shaped, Gram-stain-negative, motile, and catalase-positive and produced blue-violet-pigmented colonies on R2A agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, automated ribotyping, repetitive element sequence-based PCR (rep-PCR), MALDI-TOF MS, fatty acid profile, chemotaxonomy analyses, and extensive biotyping was applied in order to clarify the taxonomic position of these isolates. Phylogenetic analysis based on the 16S rRNA gene indicated that all the isolates constituted a coherent group belonging to the genus Rugamonas. The closest relatives to the representative isolate P5900T were Rugamonas rubra CCM 3730T, Rugamonas rivuli FT103WT, and Rugamonas aquatica FT29WT, exhibiting 99.2%, 99.1%, and 98.6% 16S rRNA pairwise similarity, respectively. The average nucleotide identity and digital DNA-DNA hybridization values calculated from the whole-genome sequencing data clearly proved that P5900T represents a distinct Rugamonas species. The G+C content of genomic DNAs was 66.1 mol%. The major components in fatty acid profiles were summed feature 3 (C16:1 ω7c/C16:1 ω6c), C 16:0, and C12:0. The cellular quinone content contained exclusively ubiquinone Q-8. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The polyamine pattern was composed of putrescine, 2-hydroxputrescine, and spermidine.IMPORTANCE Our polyphasic approach provides a new understanding of the taxonomy of novel pigmented Rugamonas species isolated from freshwater samples in Antarctica. The isolates showed considerable extracellular bactericidal secretions. The antagonistic activity of studied isolates against selected pathogens was proved by this study and implied the importance of such compounds’ production among aquatic bacteria. The psychrophilic and violacein-producing species Roseomonas violacea may play a role in the diverse consortium among pigmented bacteria in the Antarctic water environment. Based on all the obtained results, we propose a novel species for which the name Rugamonas violacea sp. nov. is suggested, with the type strain P5900T (CCM 8940T; LMG 32105T). Isolates of R. violacea were obtained from different aquatic localities, and they represent the autochthonous part of the water microbiome in Antarctica.

Rice leaf associated Chryseobacterium species: An untapped antagonistic flavobacterium displays volatile mediated suppression of rice blast disease

Rice phyllosphere-associated pigmented bacteria were characterized and identified as Chryseobacterium based on 16S rRNA gene sequencing and phenotypic fingerprinting by Biolog. Molecular phylogenetic analysis by maximum likelihood method clustered the leaf Chryseobacterium with plant or soil-associated Chryseobacterium taklimakanense (OsEp-PSA33); Chryseobacterium camaliae (OsEnb-ALM-D20, OsEnb-ALM-D11); Chryseobacterium culicis (OsEnb-ALM-C23, OsEp-PPA23, OsEp-PPA6, OsEnb-ALM-D3); and Chryseobacterium endophyticum (OsEnb-ALM-A6, OsEnb-ALM-A22). Activity testing of Chryseobacterium isolates showed excellent antifungal activity with over 80.0 % mycelial growth inhibition of Magnaporthe oryzae. The Chryseobacterium endophyticum OsEnb-ALM-A6 and OsEnb-ALM-A22 showed over 90 % fungal growth inhibition by volatile compounds. Chemical analysis of volatiles emitted by Chryseobacterium indicated the abundance of 2-Ethyl-hexanol; 1-Hexadecene; 2-Hexyl-decanol; Heptanal; Furan-diol; and Octanal. Upon seed or seedling bacterization, Chryseobacterium endophyticum not only triggered altered growth pattern of rice but also suppressed blast disease (40.0 % reduction over mock). qPCR-based transcriptional analysis showed enhanced expression of defense associated OsCEBiP, OsCERK, OsPAD4, OsNPR1.3, and OsFMO1. The volatile mediated antifungal activity and host defense induction by Chryseobacterium can be a potential alternative to fungicide-based blast management.