Chromobacterium Species Research Articles

Chromobacterium sp. septicemia in Sweden. A clinical case report

BackgroundChromobacterium is a genus of fourteen species with validly published names, most often found in soil and waters in tropical and subtropical regions around the world. The most well-known species of the genus, C. violaceum, occasionally causes clinically relevant infections; cases of soft tissue infections with septicemia and fatal outcomes have been described.Case presentationHere, we present a clinical case report of a 79-year-old man from Sweden with a soft-tissue infection and septicemia. The pathogen was identified as a strain of Chromobacterium species, but not C. violaceum. The patient was treated with clindamycin and ciprofloxacin and recovered well.ConclusionsThis case report demonstrates the potential of Chromobacterium species as infectious agents in immunocompetent patients. It also indicates the existence of a novel species.

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.

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.

Chromobacterium Csp_P biopesticide is toxic to larvae of three Diabrotica species including strains resistant to Bacillus thuringiensis

The development of new biopesticides to control the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is urgent due to resistance evolution to various control methods. We tested an air-dried non-live preparation of Chromobacterium species Panama (Csp_P), against multiple corn rootworm species, including Bt-resistant and -susceptible WCR strains, northern (NCR, D. barberi Smith & Lawrence), and southern corn rootworm (SCR, D. undecimpunctata howardi Barber), in diet toxicity assays. Our results documented that Csp_P was toxic to all three corn rootworms species based on lethal (LC50), effective (EC50), and molt inhibition concentration (MIC50). In general, toxicity of Csp_P was similar among all WCR strains and ~ 3-fold less toxic to NCR and SCR strains. Effective concentration (EC50) was also similar among WCR and SCR strains, and 5-7-fold higher in NCR strains. Molt inhibition (MIC50) was similar among all corn rootworm strains except NCR diapause strain that was 2.5–6-fold higher when compared to all other strains. There was no apparent cross-resistance between Csp_P and any of the currently available Bt proteins. Our results indicate that Csp_P formulation was effective at killing multiple corn rootworm strains including Bt-resistant WCR and could be developed as a potential new management tool for WCR control.

Integrated into Environmental Biofilm Chromobacterium vaccinii Survives Winter with Support of Bacterial Community.

Chromobacterium species are common in tropical and subtropical zones in environmental samples according to numerous studies. Here, we describe an environmental case of resident Chromobacterium vaccinii in biofilms associated with Carex spp. roots in Moscow region, Russia (warm-summer humid continental climate zone). We performed broad characterization of individual properties as well as surrounding context for better understanding of the premise of C. vaccinii survival during the winter season. Genome properties of isolated strains propose some insights into adaptation to habit and biofilm mode of life, including social cheaters carrying ΔluxR mutation. Isolated C. vaccinii differs from previously described strains in some biochemical properties and some basic characteristics like fatty acid composition as well as unique genome features. Despite potential to modulate membrane fluidity and presence of several genes responsible for cold shock response, isolated C. vaccinii did not survive during exposure to 4 °C, while in the complex biofilm sample, it was safely preserved for at least half a year in vitro at 4 °C. The surrounding bacterial community within the same biofilm with C. vaccinii represented a series of psychrophilic bacterial species, which may share resistance to low temperatures with other species within biofilm and provide C. vaccinii an opportunity to survive during the cold winter season.

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.

Evaluation of the Bacteriological Diversity and the Physicochemical Properties of Kolo-Creek Oil Field Wastewater

Evaluation of bacteriological diversity and physicochemical parameters as well as the heavy metals present in the water samples collected from Kolo creek flow station located in Bayelsa State in the Niger Delta, Nigeria was carried out for the period of eight months (March to October). Oilfield wastewater samples were obtained in four different locations of the Kolo creek in sterile bottles and were transported to the Microbiology Laboratory of the Rivers State University for analysis.10-fold serial dilutions were carried out and aliquots of 0.1 ml were inoculated and spread plated unto sterile nutrient agar, MacConkey agar and mineral salt agar plates. The water samples were analyzed for the total heterotrophic bacteria, coliform bacteria and hydrocarbon utilizing bacteria. The total heterotrophic and coliform bacteria load in log10CFU/ml ranged from 6.25 to 13.62 and 4.04 to 5.75 respectively, while the hydrocarbon utilizing bacteria ranged from 0 to 4.81. Higher Mean monthly counts of the total heterotrophic bacteria, coliform bacteria and hydrocarbon utilizing bacteria were 13.48 in March, 5.44 in April and 4.51 log10 CFU/ml in March, respectively. While lower mean monthly counts recorded were 6.72 in August, 4.29 in August and 0 log10CFU/ml in April, respectively. Fifteen bacteria belonging to Micrococcus, Chromobacterium, Listeria, Actinomyces, Staphylococcus, Bacillus, Enterobacter, Serratia, Escherichia coli, Vibrio cholera, Vibrio parahaemolyticus, Proteus, Shigella, Pseudomonas and Acinetobacter species were identified. While Bacillus, Pseudomonas, Serratia, Micrococcus, Proteus, and Acinetobacter species were the hydrocarbon utilizing bacteria identified. The bacteria populations varied across the months. The physicochemical parameters as well as the heavy metals were within the permissible limits set by regulatory bodies. The hydrocarbon utilizing bacteria in this study could be used for bioremediation study.

Microbial Biopesticides in Agroecosystems

Microbial biopesticides include several microorganisms like bacteria, fungi, baculoviruses, and nematode-associated bacteria acting against invertebrate pests in agro-ecosystems. The biopesticide sector is experiencing a significant growth and many discoveries are being developed into new biopesticidal products that are fueling a growing global market offer. Following a few decades of successful use of the entomopathogenic bacterium Bacillus thuringiensis and a few other microbial species, recent academic and industrial efforts have led to the discovery of new microbial species and strains, and of their specific toxins and virulence factors. Many of these have, therefore, been developed into commercial products. Bacterial entomopathogens include several Bacillaceae, Serratia, Pseudomonas, Yersinia, Burkholderia, Chromobacterium, Streptomyces, and Saccharopolyspora species, while fungi comprise different strains of Beauveria bassiana, B. brongniartii, Metarhizium anisopliae, Verticillium, Lecanicillium, Hirsutella, Paecilomyces, and Isaria species. Baculoviruses are species-specific and refer to niche products active against chewing insects, especially Lepidopteran caterpillars. Entomopathogenic nematodes (EPNs) mainly include species in the genera Heterorhabditis and Steinernema associated with mutualistic symbiotic bacteria belonging to the genera Photorhabdus and Xenorhabdus. An updated representation of the current knowledge on microbial biopesticides and of the availability of active substances that can be used in integrated pest management programs in agro-ecosystems is reported here.

Hydrogen cyanide produced by the soil bacterium Chromobacterium sp. Panama contributes to mortality in Anopheles gambiae mosquito larvae

Mosquito larvae continuously encounter microbes in their aquatic environment, which serve as food and play a critical role in successful development. In previous work, we isolated a Chromobacterium sp. (C.sp_P) with larvicidal activity from the midgut of dengue vector Aedes mosquitoes in Panama. In this study, we found a positive correlation between initial concentrations of C.sp_P and larval mortality rates, and that C.sp_P is more efficient at inducing larval mortality in a high nutrient environment. Multiple Chromobacterium species induce larval mortality with similar efficacy to C.sp_P except for C. subtsugae. We also found that a non-lethal dose of C.sp_P lengthens development time and increases mortality over multiple developmental stages, suggesting persistent effects of exposure. Additionally, we showed that larvicidal activity persists in the larval breeding water after removal of live bacteria, and that the larvicidal factor in C.sp_P-treated water is smaller than 3 kDa, heat resistant to 90 °C, and lost after vacuum centrifugation. We showed that C.sp_P produces hydrogen cyanide in culture and in larval water at concentrations sufficient to kill An. gambiae larvae, and treatment of the larval water with a cyanide antidote eliminated larvicidal activity. We conclude that a potential mechanism by which C.sp_P can induce larval mortality is via production of hydrogen cyanide.

Aminopeptidase secreted by Chromobacterium sp. Panama inhibits dengue virus infection by degrading the E protein.

Dengue virus (DENV) is the most prevalent and burdensome arbovirus transmitted by Aedes mosquitoes, against which there is only a limited licensed vaccine and no approved drug treatment. A Chromobacterium species, C. sp. Panama, isolated from the midgut of A. aegypti is able to inhibit DENV replication within the mosquito and in vitro. Here we show that C. sp. Panama mediates its anti-DENV activity through secreted factors that are proteinous in nature. The inhibitory effect occurs prior to virus attachment to cells, and is attributed to a factor that destabilizes the virion by promoting the degradation of the viral envelope protein. Bioassay-guided fractionation, coupled with mass spectrometry, allowed for the identification of a C. sp. Panama-secreted neutral protease and an aminopeptidase that are co-expressed and appear to act synergistically to degrade the viral envelope (E) protein and thus prevent viral attachment and subsequent infection of cells. This is the first study characterizing the anti-DENV activity of a common soil and mosquito-associated bacterium, thereby contributing towards understanding how such bacteria may limit disease transmission, and providing new tools for dengue prevention and therapeutics.

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.

Chromobacterium spp. harbour Ambler class A β-lactamases showing high identity with KPC.

The origin of KPC is unknown. The aim of this study was to detect progenitors of KPC in silico and to functionally verify their β-lactam hydrolysis activity. The sequence of KPC-2 was used to mine the NCBI protein sequence database. The best non-KPC hits were analysed by amino acid (aa) alignment and phylogenetic tree construction. Genes encoding KPC-2 homologues were expressed in Escherichia coli. The carbapenemase activities of the recombinant strains were characterized by the CarbaNP test and UV spectrophotometry and MICs of selected β-lactams were determined. Genes encoding the closest KPC-2 homologues were identified on the chromosome of Chromobacterium piscinae strain ND17 (CRP-1, 76% aa identity), Chromobacterium sp. C-61 (CRS-1, 70% aa identity) and Chromobacterium haemolyticum DSM19808 (CRH-1, 69% aa identity). All three Chromobacterium β-lactamases were phylogenetically more related to KPC than to other Ambler class A β-lactamases. The 27 bp region preceding the start codon of blaCRP-1 displayed high nucleotide identity to the corresponding region upstream from blaKPC (74%). Heterologous expression of blaCRP-1 and to a lesser extent of blaCRH-1 in E. coli significantly increased the MICs of meropenem and most cephalosporins. The CarbaNP test was positive for both recombinant strains, but spectrophotometric analysis confirmed higher carbapenemase activity for CRP-1-producing clones. The recovery of three class A β-lactamases with up to 76% aa identity to KPC from distinct Chromobacterium species is highly indicative of the role played by this genus in the evolution of KPC.

Synergistic effect of crude oil plus dispersant on bacterial community in a louisiana salt marsh sediment.

A combined effect of crude oil plus dispersant (Corexit 9500A) significantly altered indigenous bacterial communities in a Louisiana salt marsh sediment after 30 days of incubation; the crude oil and/or Corexit 9500A treatments triggered shifts in bacterial communities and the shifted bacterial structure by crude oil plus Corexit 9500A was considerably different from those by either crude oil or Corexit 9500A. However, the synergistic effect of crude oil plus Corexit 9500A was not observed after 7 days of incubation; the bacterial community was slightly shifted by Corexit 9500A and the crude oil did not trigger any bacterial community shift after 7 days of incubation. DNA sequencing data indicated that Chromobacterium species was enriched in the Corexit 9500A microcosms after 7 days of incubation, while Pseudomonas, Advenella, Acidocella and Dyella spp. were enriched after 30 days of incubation. Parvibaculum was a dominant species in the crude oil microcosms after 30 days of incubation. Rhodanobacter, Dyella and Frateuria spp. were dominant in crude oil plus Corexit 9500A microcosms after 30 days of incubation. Our data show that the effect of crude oil plus Corexit 9500A on bacterial community is synergistic, and thus the dispersant effect should be considered with the spilled oil to correctly evaluate the environmental impact.

English

The bacterium Chromobacterium violaceum had its genome sequenced by the Genome Consortium in 2002, revealing a number of genes with potential for use in pharmacological and industrial biotechnology. However, only a few studies have been conducted to establish the molecular characterization of the different isolates of C. violaceum. Thus, the present study aimed to identify the isolates of Chromobacterium through their fatty acid profile and partial sequencing of the 16S rDNA gene. The results show that, unlike previously studied isolates, the profiles of UCP1035, UCP1489 and UCP1466 contained the saturated fatty acid palmitoleic (C16: 1). Corroborating data from the 16S rDNA phylogeny revealed that although most isolates from Chromobacterium were grouped as cluster 1 isolates, UCP1035 and UCP1466 formed monophyletic branches. The isolate UCP1489 and isolates from Chromobacterium piscinae were grouped in cluster 2. The data obtained from each Chromobacterium species in the tree showed that only the UCP1462, UCP1469 and UCP1470 isolates exhibited 100% identity with the species C. violaceum ATCC12472 and Chromobacterium pseudoviolaceum LMG3953T. These data shed light on the genetic diversity of bacteria whose genes may have biological functions but have not yet been characterized for their biotechnological potential.   Key words: Chromobacterium violaceum, Chromobacterium pseudoviolaceum, fingerprinting, fatty acids, 16S rDNA, genetic diversity.

Chromobacterium vaccinii sp. nov., isolated from native and cultivated cranberry (Vaccinium macrocarpon Ait.) bogs and irrigation ponds

A large number of Gram-negative, motile, mesophilic, violacein-producing bacteria were isolated from the soils and roots of Vaccinium macrocarpon Ait. and Kalmia angustifolia L. plants and from irrigation ponds associated with wild and cultivated cranberry bogs in Massachusetts, USA. Phylogenetic analyses of 16S rRNA gene sequences placed these isolates in a clade with Chromobacterium species, but the specialized environment from which they were isolated, their low genomic DNA relatedness with Chromobacterium violaceum ATCC 12472(T) and C. subtsugae PRAA4-1(T), significant differences in fatty acid composition and colony morphology indicate that the cranberry and Kalmia isolates comprise a separate species of Chromobacterium, for which the name Chromobacterium vaccinii sp. nov. is proposed. Strain MWU205(T) ( = ATCC BAA-2314(T) = DSM 25150(T)) is proposed as the type strain for the novel species. Phenotypic analysis of 26 independent isolates of C. vaccinii sp. nov. indicates that, despite close geographical and biological proximity, there is considerable metabolic diversity among individuals within the population.

Chromobacterium violaceum—A Rare Cause of Infected Pancreatic Pseudocyst

In Brief Of the 2 species of Chromobacterium, Chromobacterium violaceum has been rarely implicated in human disease. It is a bacterium of low virulence causing occasional localized infection and sepsis. We report a case of C. violaceum infection of pancreatic pseudocyst. The patient was treated by cystojejunostomy with Roux-en-Y jejunal loop and antimicrobial therapy with ciprofloxacin and amikacin. As sepsis due to this organism is associated with high mortality, empiric therapy with fluoroquinolones and aminoglycosides is recommended, along with proper surgical management. C. violaceum is an extremely rare cause of pancreatic pseudocyst infection. Given the fact that sepsis due to this organism is associated with high mortality, initial empiric therapy with drugs such as fluoroquinolones and aminoglycosides is recommended, along with proper surgical management to bring about complete resolution. The prognosis should be guarded even when the infection appears to be localized, because of its propensity to disseminate.

Chromobacterium piscinae sp. nov. and Chromobacterium pseudoviolaceum sp. nov., from environmental samples

Two strains (LMG 3947 and LMG 3953) of motile, Gram-negative, violet-pigmented bacteria, respectively isolated in 1972 and before 1953 from environmental samples and previously assigned to Chromobacterium violaceum, were studied again in detail for their taxonomic position. 16S rRNA gene sequence analysis showed that both strains clustered together with the type strain of Chromobacterium violaceum (99.8 % sequence similarity for strain LMG 3953(T) and 98.9 % sequence similarity for LMG 3947(T)). recA sequence similarities were significantly lower (95-96 %), and fatty acid profiles were also different from those reported for C. violaceum and other Chromobacterium species. Both strains exhibit polar-lipid profiles consisting of the major compound phosphatidylethanolamine and moderate amounts of phosphatidylglycerol in addition to some minor lipids. The quinone systems consist of the major compound ubiquinone Q-8 and moderate amounts of Q-7. Polyamine patterns are composed of the major compounds putrescine and 2-hydroxyputrescine, moderate amounts of 1,3-diaminopropane and variable amounts of cadaverine and spermidine. The results of DNA-DNA hybridizations and physiological as well as biochemical tests allowed both genotypic and phenotypic differentiation of the two strains from described Chromobacterium species. It is evident from the genotypic and phenotypic data that both strains represent novel species in the genus Chromobacterium, for which we propose the names Chromobacterium piscinae sp. nov. (type strain LMG 3947(T) =CCM 3329(T)) and Chromobacterium pseudoviolaceum sp. nov. (type strain LMG 3953(T) =CCM 2076(T) =NCIMB [corrected] 8182(T)).

The effect of infection byPomphorhynchus laevis(Acanthocephala) on the composition of the intestinal bacterial flora in flounder,Platichthys flesus

A total of 112 flounder,Platichthys flesus, was surveyed for the presence ofPomphorhynchus laevis(Acanthocephala). No acanthocephalans were found in 35 fish, 40 fish were infected with 1–5 thorny-headed worms, and in 37 fish the intensity of infection exceeded 6. The fish surveyed were also studied for the composition of the resident microflora of the terminal portion of the intestine—the characteristic site forP. laevis. It turned out the number of worms was positively correlated with the bacterial count. The bacteria cultured from the material sampled from intestines of infected- and non-infected fish exhibited similar specific composition and the differences were only in the intensity of individual species. The most frequently isolated bacteria, represented the genera:Aeromonas, PseudomonasandShewanella. The least frequent were species ofChromobacterium, Escherichia, ProvidenciaandSerratia. The presently reported study results, suggest that bacteria species, constituting physiological bacterial flora, may become, under certain conditions, potentially pathogenic, through substantial increase in their abundance. The factor responsible for disturbing the natural balance in the intestine may be the thorny-headed worm,Pomphorhynchus laevis.