Genus Chromobacterium Research Articles

Chromobacterium indicum sp. nov., a Pigment-Producing Bacterium Isolated from Soil.

A purple colony, designated as TRC1.1.SA was isolated from a tea garden soil sample. It was a Gram-negative, rod-shaped, non-spore-forming and motile bacterium. The strain TRC1.1.SAT grew aerobically at temperatures 15-37℃ and pH levels 5.0-9.0. It showed both oxidase and catalase activity. The 16S rRNA gene sequence blast analysis revealed identity with the members of the genus Chromobacterium. The maximum identity was with the type strains of species Chromobacterium piscinae CCM 3329T (99.8%), C. vaccinii MWU205T (99.7%), and C. violaceum ATCC 12472T (98.7%). However, the average nucleotide identity (ANI) of the genome sequence showed less than 96% similarity with all species of the genus Chromobacterium. Further, digital DNA-DNA hybridization (dDDH) revealed the highest identity of 63.4% with its phylogenetic relative C. piscinae CCM 3329T. The G + C content of the strain was 63.9%. The major polar lipids identified were phosphatidylethanolamine (PE), diphosphatidylglycerol (DPG), and phosphoglyceraldehyde (PG). Fatty acid analysis showed C16:0, C16:1ω7c, C17:0 cyclo, and C18:1ω7c as the major fatty acids. RAST and antiSMASH analyses of the genome revealed the presence of a biosynthetic gene cluster (BGC) involved in the production of violacein pigment, as observed for type species C. violaceum ATCC 12472T. Considering the phenotypic differences and genomic identity, strain TRC1.1.SAT is assigned as a novel species of the genus Chromobacterium, for which the name Chromobacterium indicum is proposed. The type strain of prospective species is designated as TRC1.1.SAT (= MTCC 13391T; JCM 36723T; = KCTC 8324T).

Isolation and characterization of Chromobacterium violaceum and antibacterial activities of its metabolite violacein

Violacein is a naturally-occurring bacterial secondary metabolite which is known to demonstrate a wide range of biological properties including antibacterial, antifungal, antiviral as well as anticancer and antitumor activities. Bacteria belonging to the genus Chromobacterium are the most studied microorganisms for violacein production. In this study, indigenous violacein-producing Chromobacterium violaceum was isolated from water and sediment samples of Bijaypur white clay hill lake, Netrokona, Bangladesh, and identified by biochemical and molecular characterization. After confirming the presence of the vioB gene in a polymerase chain reaction, crude violacein was purified from C. violaceum CV1 by ethanol extraction followed by filtration through 0.22 µm syringe filters. The partially-purified pigment exhibited significant antibacterial activity against three Gram-positive pathogens; Staphylococcus aureus, Streptococcus sp, and Listeria monocytogenes, with the later demonstrating the highest sensitivity. The bactericidal activity was more pronounced when combined with an antibiotic, thereby producing a drug-metabolite synergistic antibacterial activity. Dhaka Univ. J. Biol. Sci. 33(1): 109-119, 2024 (January)

Partial genomic characterization of Chromobacterium piscinae from India reveals multi drug resistance.

Species of genus Chromobacterium have been isolated from diverse geographical settings, which exhibits significant metabolic flexibility as well as biotechnological and pathogenic properties. This study describes the isolation, characterization, draft assembly, and detailed sequence analysis of Chromobacterium piscinae strain W1B-CG-NIBSM isolated from water samples from multi use community pond. The organism was characterized by biochemical tests, Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI TOF-MS) and partial genome sequencing. The partial genomic data ofChromobacterium pisciane isolate W1B NIBSM strainwas submitted to GenBank with Bio project number PRJNA803347 and accession no CP092474. An integrated genome analysis of Chromobacterium piscinae has been accomplished with PATRIC which indicates good quality genome. DNA sequencing using the illumina HiSeq 4000 system generated total length of 4,155,481bp with 63 contig with G + C content is 62.69%. This partial genome contains 4,126 protein-coding sequences (CDS), 27 repeats region and 78 transfer RNA (tRNA) genes as well as 3 ribosomal RNA (rRNA) genes. The genomic annotation of Chromobacterium W1B depicts 2,925 proteins with functional assignments and 1201 hypothetical proteins. A repertoire of specialty genes implicated in antibiotic resistance (45 genes), drug target (6 genes), Transporter (3 genes) and virulence factor (10 genes). The genomic analysis reveals the adaptability, displays metabolic varied pathways and shows specific structural complex and various virulence factors which makes this strain multi drug resistant. The isolate was found to be highly resistant to β-lactam antibiotics whereas it showed sensitivity towards aminoglycosides and fluoroquinolone antibiotics. Hence, the recovery of Chromobacterium piscinae from community pond evidenced for uncertain hidden source of public health hazard. To the best of authors knowledge this is first report of isolation and genomic description of C. piscinae from India.

Identification of 2,4-diacetylphloroglucinol production in the genus Chromobacterium

The compound 2,4-diacetylphloroglucinol (DAPG) is a broad-spectrum antibiotic that is primarily produced by Pseudomonas spp. DAPG plays an important role in the biocontrol disease suppressing activity of Pseudomonas spp. In the current study, we report the discovery of the DAPG biosynthetic cluster in strains of Chromobacterium vaccinii isolated from Brazilian aquatic environments and the distribution of the biosynthetic cluster in the Chromobacterium genus. Phylogenetic analysis of the phlD protein suggests the biosynthetic cluster probably entered the genus of Chromobacterium after a horizontal gene transfer event with a member of the Pseudomonas fluorescens group. We were able to detect trace amounts of DAPG in wild type cultures and confirm the function of the cluster with heterologous expression in Escherichia coli. In addition, we identified and verified the presence of other secondary metabolites in these strains. We also confirmed the ability of C. vaccinii strains to produce bioactive pigment violacein and bioactive cyclic depsipeptide FR900359. Both compounds have been reported to have antimicrobial and insecticidal activities. These compounds suggest strains of C. vaccinii should be further explored for their potential as biocontrol agents.

Meningitis caused by Chromobacterium haemolyticum suspected to be derived from a canal in Japan: a case report

BackgroundThe genus Chromobacterium, of which 12 species have been recognized, comprises bacteria that reside in tropical and subtropical environments. Of these species, Chromobacterium violaceum and Chromobacterium haemolyticum are known to cause infections in humans. There have been few reports of infections caused by Chromobacterium haemolyticum.Case presentationChromobacterium haemolyticum was detected in spinal fluid and blood samples isolated from a 73-year-old Japanese male patient who fell into a canal in Kyoto City, Japan and developed bacteremia and meningitis. Although meropenem and vancomycin were administered, this patient died 9 days after admission. Although the infection was misidentified as being caused by Chromobacterium violaceum by conventional identification methods, average nucleotide identity analysis revealed that the causative pathogen was Chromobacterium haemolyticum. The same bacteria were also detected in the canal in which the accident occurred. Phylogenetic analysis of the strain isolated from the patient and the strain isolated from the canal suggested that the two strains were very closely related.ConclusionsChromobacterium haemolyticum can be misidentified as Chromobacterium violaceum by conventional identification methods and tends to be more resistant to β-lactams than Chromobacterium violaceum. Pigment production and β-hemolysis on blood sheep agar can provide clues for the early identification of Chromobacterium haemolyticum.

Phenotypic plasticity and characterization of Chromobacterium isolates from aquatic environment

The genus Chromobacterium spp. are gram-negative bacilli, which may or may not have characteristic purple pigmentation, and are mainly isolated from soil, water and infected patients. The main representative species of this genus is C. violaceum, responsible for a high mortality rate among those infected. The aim of this study was to genetically characterize and broadly compare phenotypic characteristics between the genus Chromobacterium species described in the literatureand bacterial isolates. This study is an experimental research, in which sequencing and phenotypic tests of bacterial isolates were carried out for comparison with species of the genus Chromobacterium. Two strains were identified, CRJL01 and CRJL02 that have characteristics of Chromobacterium spp species. These isolates showed high resistance to antibiotics, tolerance and resistance to metals, biochemical and physiological versatility of the CRJL01 and CRJL02 strains. In the sequencing of the 16S rRNA gene, the CRJL01 strain showed similarity with the C. piscinae strain. The CRJL02 strain showed similarity with the C. subtsugae strain. This work is the first report in 40 years of Chromobacterium spp. in the Brazilian Midwest – Goiás, in water samples. This isolated genus has a wide applicability for the pharmaceutical, food and cosmetic industries, due to the production of its purple/violet pigment known as violacein, and its bioprospecting is of great importance. Thus, this study is a kick-off for exploring your produced pigment.

Bee pollen in zebrafish diet affects intestinal microbiota composition and skin cutaneous melanoma development

Bee pollen is recommended as dietary supplement due to immunostimulating functions including antioxidant, anti-inflammatory and anti-carcinogenic properties. Nevertheless, the effectiveness of such properties is still not well understood. As diet can be associated with animal performance, microbiota modulation and potentially factor for cancer, this study aimed to analyze if bee pollen could influence growth, gut microbial and skin cutaneous melanoma development in zebrafish. Control diets based on commercial flakes and Artemia were compared with the same diet supplemented with bee pollen. Fish weight gain, increased length, intestinal bacteria metagenomics analysis, serum amyloid A gene expression and cutaneous melanoma transplantation assays were performed. Bee pollen affected microbiota composition and melanoma development. Differential abundance revealed higher abundance in the control group for Aeromonadaceae family, Aeromonas and Pseudomonas genus, A. sobria, A. schubertii, A. jandaei and P. alcaligenes species compared with pollen diet group. Pollen group presented higher abundance for Chromobacterium genus and for Gemmobacter aquaticus, Flavobacterium succinicans and Bifidobacterium breve compared with control group. Unexpectedly, fish fed with bee pollen showed higher tumor growth rate and larger tumor size than control group. This is the first study to report intestinal microbial changes and no protective cancer properties after bee pollen administration.

Chromobacterium alticapitis sp. nov. and Chromobacterium sinusclupearum sp. nov. isolated from wild cranberry bogs in the Cape Cod National Seashore, USA.

Two non-pigmented strains in the genus Chromobacterium, MWU14-2602T and MWU13-2610T, were isolated from wild cranberry bogs in the Cape Cod National Seashore, USA. The isolates were characterized by genomic and phenotypic analyses, the results of which indicated that they represent two novel species. Based on total genome sequences, the closest relatives were in the Chromobacterium amazonense group, which includes the recently described Chromobacterium paludis. Whole genome sequences were compared by genome blast distance phylogeny, digital DNA-DNA hybridization and average nucleotide identity analyses with each other and with the type strains of their nearest species. MWU14-2602T and MWU13-2610T fell well below the accepted cutoff values for species relatedness, clearly indicating that they represent novel species. Although little is known about these organisms in situ, under laboratory conditions, MWU13-2610T produced a modest amount of HCN and was strongly positive for exoprotease activity, whereas MWU14-2602T did not produce HCN or exoproteases. The predominant fatty acids for both isolates were summed C16 : 1ω7cis/C16 : 1ω6cis. Both isolates produced siderophores and pyomelanin pigment on rich media, and neither was haemolytic on sheep blood agar. We propose the names Chromobacterium alticapitis sp. nov. (type strain MWU14-2602T=ATCC TSD 260T=CCOS 1979T) and Chromobacterium sinusclupearum sp. nov. (type strain MWU13-2610T=ATCC TSD-259T=CCOS 1981T) for these taxa.

PhyloM: A Computer Program for Phylogenetic Inference from Measurement or Binary Data, with Bootstrapping.

Quantitative and binary results are ubiquitous in biology. Inasmuch as an underlying genetic basis for the observed variation in these observations can be assumed, it is pertinent to infer the evolutionary relationships among the entities being measured. I present a computer program, PhyloM, that takes measurement data or binary data as input, using which, it directly generates a pairwise distance matrix that can then be subjected to the popular neighbor-joining (NJ) algorithm to produce a phylogenetic tree. PhyloM also has the option of nonparametric bootstrapping for testing the level of support for the inferred phylogeny. Finally, PhyloM also allows the user to root the tree on any desired branch. PhyloM was tested on Biolog Gen III growth data from isolates within the genus Chromobacterium and the closely related Aquitalea sp. This allowed a comparison with the genotypic tree inferred from whole-genome sequences for the same set of isolates. From this comparison, it was possible to infer parallel evolution. PhyloM is a stand-alone and easy-to-use computer program with a user-friendly graphical user interface that computes pairwise distances from measurement or binary data, which can then be used to infer phylogeny using NJ using a utility in the same program. Alternatively, the distance matrix can be downloaded for use in another program for phylogenetic inference or other purposes. It does not require any software to be installed or computer code written and is open source. The executable and computer code are available on GitHub.

The inconsistent microbiota of Budu, the Malaysian fermented anchovy sauce, revealed through 16S amplicon sequencing.

Budu is a Malaysian fermented anchovy sauce produced by immersing small fishes into a brine solution for 6 to 18 months. Microbial enzymes are known to contribute to fermentation; however, not much is known about the microbial community in Budu. Therefore, a better understanding of the Budu microbiome is necessary to improve the quality, consistency, and safety of the Budu products.In this study, we collected 60 samples from 20 bottles of Budu produced by seven manufacturers. We analyzed their microbiota using V3–V4 16S rRNA amplicon sequencing when we first opened the bottle (month 0), as well as 3 and 7 months post-opening (months 3 and 7). Tetragenococcus was the dominant genus in many samples, reaching a maximum proportion of 98.62%, but was found in low abundance, or absent, in other samples. When Budu samples were not dominated by a dominant taxa, we observed a wider genera diversity such as Staphylococcus, Acinetobacter, Halanaerobium and Bacillus. While the taxonomic composition was relatively stable across sampling periods, samples from two brands showed a sudden increase in relative abundance of the genus Chromobacterium at month 7. Based on prediction of metagenome functions, non-Tetragenococcus-dominated samples were predicted to have enriched functional pathways related to amino acid metabolism and purine metabolism compared to Tetragenococcus-dominated samples; these two pathways are fundamental to fermentation quality and health attributes of fish sauce. Among the non-Tetragenococcus-dominated samples, contributions towards amino acid metabolism and purine metabolism were biased towards the dominant taxa when species evenness is low, while in samples with higher species evenness, the contributions towards the two pathways were predicted to be evenly distributed between taxa. Our results demonstrated that the utility of 16S sequencing to assess batch variation in fermented food production. The distinct microbiota was shown to correlate with characteristic metagenome function including functions potentially related to fermented food nutrition and quality.

Adaptation and cross species interaction of Chromobacterium spp. within aquatic biofilms in temperate climate zone

Members of Chromobacterium genus are found in different natural aquatic reservoirs in tropical and subtropical climate zones. Chromobacterium species are considered as tropical bacterial species and are not resistant to cold temperatures during long-term storage in laboratory conditions. Here we present isolation of a resident strain of Chromobacterium vaccinii from root-associated biofilm of Carex spp. in Volkovskoye bog (Moscow region, Russia) and describe some unusual properties of isolated strain regarding adaptation to sub-zero temperatures and community lifestyle. While interaction and cooperation with other bacterial species within biofilm are important for resistance to sub-zero temperatures, we create MALDI-TOF MS based small molecule interaction network with other bacterial species.

Efflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition Model.

Members of the Chromobacterium genus include opportunistic but often-fatal pathogens and soil saprophytes with highly versatile metabolic capabilities. In previous studies of Chromobacterium subtsugae (formerly C. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM) that confers resistance to several antibiotics, including the bactobolin antibiotic produced by the soil saprophyte Burkholderia thailandensis Here, we show the cdeAB-oprM genes increase C. subtsugae survival in a laboratory competition model with B. thailandensis We also demonstrate that adding sublethal bactobolin concentrations to the coculture increases C. subtsugae survival, but this effect is not through CdeAB-OprM. Instead, the increased survival requires a second, previously unreported pump we call CseAB-OprN. We show that in cells exposed to sublethal bactobolin concentrations, the cseAB-oprN genes are transcriptionally induced, and this corresponds to an increase in bactobolin resistance. Induction of this pump is highly specific and sensitive to bactobolin, while CdeAB-OprM appears to have a broader range of antibiotic recognition. We examine the distribution of cseAB-oprN and cdeAB-oprM gene clusters in members of the Chromobacterium genus and find the cseAB-oprN genes are limited to the nonpathogenic C. subtsugae strains, whereas the cdeAB-oprM genes are more widely distributed among members of the Chromobacterium genus. Our results provide new information on the antibiotic resistance mechanisms of Chromobacterium species and highlight the importance of efflux pumps for saprophytic bacteria existing in multispecies communities.IMPORTANCE Antibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member of the Chromobacterium genus and increases resistance to a broad range of antibiotics. The other gene cluster has more narrow antibiotic specificity and is found only in Chromobacterium subtsugae, a subset of entirely nonpathogenic species. We demonstrate the role of both pumps in increasing antibiotic resistance and demonstrate the importance of efflux-dependent resistance induction for C. subtsugae survival in a dual-species competition model. These results have implications for managing antibiotic-resistant Chromobacterium infections and for understanding the evolution of efflux pumps outside the host.

Chromobacterium phragmitis sp. nov., isolated from estuarine marshes.

Thirteen isolates of Gram-stain-negative, motile, violet-pigmented bacteria were isolated from marshes along tidal portions of the Potomac and James rivers in Maryland and Virginia, USA, respectively. 16S rRNA gene sequences and fatty acid analysis revealed a high degree of relatedness among the isolates, and genomic sequencing of two isolates, IIBBL 112-1T and IIBBL 274-1 (from the Potomac and James rivers, respectively), revealed highly similar genomic sequences, with a blast-based average nucleotide identity (ANIb) of ca. 98.7 %. Phylogenetic analysis of 16S rRNA gene sequences suggested that the species most highly related to IIBBL 112-1T were Chromobacterium amazonense, Chromobacterium subtsugae and Chromobacterium sphagni. However, deletion of a 25-nucleotide sequence that may have been horizontally acquired by both IIBBL 112-1T and C. amazonense resulted in a substantially different analysis; in the latter case, the species nearest IIBBL 112-1T were Chromobacterium violaceum, Chromobacterium vaccinii and Chromobacterium piscinae. Whole-genome alignments between either IIBBL 112-1T or IIBBL 274-1 and the type strains of C. vaccinii or C. violaceum resulted in ANIb values in the range of ca. 87 %, while alignment with C. amazonense CBMAI 310T resulted in an ANIb of ca. 83 %. Collectively, these data demonstrate that IIBBL 112-1T and IIBBL 274-1 represent a new taxon within the genus Chromobacterium. We propose the name Chromobacterium phragmitis sp. nov. for this taxon; the type strain is IIBBL 112-1T (=NRRL B-67132T=JCM 31884T).

Chromobacterium spp. mediate their anti-Plasmodium activity through secretion of the histone deacetylase inhibitor romidepsin

The Chromobacterium sp. Panama bacterium has in vivo and in vitro anti-Plasmodium properties. To assess the nature of the Chromobacterium-produced anti-Plasmodium factors, chemical partition was conducted by bioassay-guided fractionation where different fractions were assayed for activity against asexual stages of P. falciparum. The isolated compounds were further partitioned by reversed-phase FPLC followed by size-exclusion chromatography; high resolution UPLC and ESI/MS data were then collected and revealed that the most active fraction contained a cyclic depsipeptide, which was identified as romidepsin. A pure sample of this FDA-approved HDAC inhibitor allowed us to independently verify this finding, and establish that romidepsin also has potent effect against mosquito stages of the parasite’s life cycle. Genomic comparisons between C. sp. Panama and multiple species within the Chromobacterium genus further demonstrated a correlation between presence of the gene cluster responsible for romidepsin production and effective antiplasmodial activity. A romidepsin-null Chromobacterium spp. mutant loses its anti-Plasmodium properties by losing the ability to inhibit P. falciparum HDAC activity, and romidepsin is active against resistant parasites to commonly deployed antimalarials. This independent mode of action substantiates exploring a chromobacteria-based approach for malaria transmission-blocking.

The mosquito adulticidal Chromobacterium sp. Panama causes transgenerational impacts on fitness parameters and elicits xenobiotic gene responses

BackgroundVector control is critical in reducing the disease burden caused by mosquitoes, and insecticides are an effective tool to control vector populations. Resistance to common insecticides is now widespread, and novel classes of insecticides are needed. In previous work, we described the mosquitocidal activity of Chromobacterium sp. Panama (C.sp_P), a bacterium found in association with mosquitoes in natural populations. In the current work, we further explored the effects of exposure to the bacterium on mosquito fitness and mosquito physiology.ResultsWe found that C.sp_P has mosquitocidal activity against a broad range of mosquito taxa. When exposed to C.sp_P as adults, female An. gambiae suffered reduced longevity, but experienced no change in fecundity. The offspring of these females, however, had higher mortality as larvae and were slower to develop compared to offspring of control females. We also found that the mosquitocidal activity of C.sp_P was retained after removal of live cells from biofilm culture media, suggesting the bacteria secrete mosquitocidal compound(s) into the media during growth. Exposure to this cell-free C.sp_P-conditioned media caused female midgut transcriptional changes comprising detoxification, xenobiotic response, and stress response genes, suggesting the physiological response to C.sp_P is similar to that of insecticide exposure. Finally, we found that multiple members of the Chromobacterium genus had mosquitocidal activity, but this activity was highest in mosquitoes treated with C.sp_P.ConclusionsOur findings suggest that C.sp_P produces factor(s) with strong effects on mosquito longevity and fitness, which may be of interest for mosquitocide development. More generally, they indicate that further exploration of mosquito-associated and environmental microbes for novel insecticidal compounds or biocontrol agents is warranted.

Insights into the Genome Sequence of Chromobacterium amazonense Isolated from a Tropical Freshwater Lake.

Members of the genus Chromobacterium have been isolated from geographically diverse ecosystems and exhibit considerable metabolic flexibility, as well as biotechnological and pathogenic properties in some species. This study reports the draft assembly and detailed sequence analysis of Chromobacterium amazonense strain 56AF. The de novo-assembled genome is 4,556,707 bp in size and contains 4294 protein-coding and 95 RNA genes, including 88 tRNA, six rRNA, and one tmRNA operon. A repertoire of genes implicated in virulence, for example, hemolysin, hemolytic enterotoxins, colicin V, lytic proteins, and Nudix hydrolases, is present. The genome also contains a collection of genes of biotechnological interest, including esterases, lipase, auxins, chitinases, phytoene synthase and phytoene desaturase, polyhydroxyalkanoates, violacein, plastocyanin/azurin, and detoxifying compounds. Importantly, unlike other Chromobacterium species, the 56AF genome contains genes for pore-forming toxin alpha-hemolysin, a type IV secretion system, among others. The analysis of the C. amazonense strain 56AF genome reveals the versatility, adaptability, and biotechnological potential of this bacterium. This study provides molecular information that may pave the way for further comparative genomics and functional studies involving Chromobacterium-related isolates and improves our understanding of the global genomic diversity of Chromobacterium species.

Chromobacterium violaceum Pathogenicity: Updates and Insights from Genome Sequencing of Novel Chromobacterium Species.

Chromobacterium violaceum is an abundant component of the soil and water microbiota in tropical and subtropical regions around the world. For many years, it was mainly known as a producer of violacein and as a reporter for the discovery of quorum sensing molecules. However, C. violaceum has recently emerged as an important model of an environmental opportunistic pathogen. Its high virulence in human infections and a mouse infection model involves the possession of several predicted virulence traits, including two type III secretion systems (T3SSs). In this article, in addition to providing an update on the new clinical cases of human C. violaceum infections, we will focus on recent advances in understanding the molecular mechanisms regarding C. violaceum pathogenesis. It has been demonstrated that the C. violaceum Cpi-1 T3SS plays a pivotal role in interaction with host cells. It is required for the secretion of effector proteins and is the agonist recognized by the Nod-like receptor CARD domain-containing protein 4 (NLRC4) inflammasome from innate immune cells. Pyroptosis and its release of hepatocytes for killing by neutrophils are key events required for the clearance of C. violaceum. Given the prominent role of T3SSs in C. violaceum virulence, we examine their occurrence in the Chromobacterium genus, taking advantage of several draft genome sequences of Chromobacterium species that have recently become available. Our finding that the Cpi-1 T3SS is widespread among Chromobacterium species points toward the pathogenic potential of this genus for humans or to novel roles of the T3SS in the interaction of Chromobacterium species with other organisms.

Draft Genome Sequence of Chromobacterium pseudoviolaceum LMG 3953T, an Enigmatic Member of the Genus Chromobacterium.

ABSTRACTChromobacterium pseudoviolaceum LMG 3953T was separated from Chromobacterium violaceum in 2009, but little is known of its origin or environmental role. Here, the genome of LMG 3953T was sequenced to understand the evolution of the genus Chromobacterium. It is not clear from this sequence that C. pseudoviolaceum is taxonomically distinct from C. violaceum.

Isolation and characterization of a novel Gram-negative bacterium Chromobacterium alkanivorans sp. nov., strain IITR-71T degrading halogenated alkanes.

The taxonomic position of a Gram-stain negative, non-violaceinpigmented bacterium isolated from an insecticide-contaminated site was characterized by a polyphasic approach. The bacterium was able to grow on three different halogenated compounds namely 1-hlorobutane, 1-hloropropane and 1,2-ichloroethane. As a critical step in the degradation of these haloalkanes, stoichiometric amounts of dechlorination were estimated. Based on selective enrichment method for three months, using a highly contaminated mixed chemical soil, a bacterium was obtained and designated as IITR-71T. Its versatility and novelty led us to further characterize it by polyphasic taxonomy. The 16S rRNA gene sequence (1446 bases) comparison showed highest similarity with those of members of the genus Chromobacterium with the most closely related species to strain IITR-71T being Chromobacterium aquaticum (99.3 %) followed by Chromobacterium haemolyticum (98.6 %) and Chromobacterium piscinae (97.1 %). The major ubiquinone was Q-8. Predominant polar lipids are phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG). The DNA G+C content of IITR-71T was estimated to be 61.2 mol%. The genotypic and phenotypic distinctiveness of IITR-71T and its phylogenetic relationships indicate that IITR-71T represents a novel species, for which the name Chromobacterium alkanivorans sp. nov. is proposed. The type strain is IITR-71T (=MTCC 11059T=JCM 30068T=KCTC 52433T).

Chromobacterium rhizoryzae sp. nov., isolated from rice roots.

A novel facultatively anaerobic, rod-shaped bacterium, designated LAM1188T, was isolated from the roots of rice (Oryzasativa) in Hubei Province. Cells of LAM1188T were Gram-stain-negative and motile. The temperature and pH ranges for growth were 15-40 °C (optimum: 30 °C) and pH 5-10 (optimum: pH 7), respectively. The strain did not require NaCl for growth but tolerated up to 3.5 % NaCl (w/v). Analysis of the 16S rRNA gene sequence indicated that the isolate represented a member of the genus Chromobacterium, and was most closely related to Chromobacterium haemolyticum MDA0585T and Chromobacterium aquaticum CC-SEYA-1T with 98.7 % and 97.3 % sequence similarity, respectively. The values of DNA-DNA hybridization between LAM1188T and C. haemolyticum JCM 14163T and C. aquaticum CCUG 55175T were 54.0±2.1 % and 44.0±1.2 %, respectively. The major cellular fatty acids were C16 : 0 and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). The main polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, four unidentified aminolipids and four unidentified lipids. The respiratory quinone was ubiquinone Q-8. The DNA G+C content was 64.1 mol% as determined by the Tm method. On the basis of its phenotypic, chemotaxonomic and phylogenetic characteristics, strain LAM1188T is suggested to represent a novel species of the genus Chromobacterium, for which the name Chromobacte riumrhizoryzae sp. nov. is proposed. The type strain is LAM1188T (=ACCC 19900T=JCM 31180T).