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Like other seafood products, tuna is highly perishable and sensitive to microbial spoilage. Its consumption, whether fresh or canned, can lead to severe food poisoning due to the activity of specific microorganisms, including histamine-producing bacteria. Yet many grey areas persist regarding their ecology, conditions of emergence and proliferation in fish. In this study, we used 16S rDNA barcoding to investigate post-mortem changes in the bacteriome of fresh and brine-frozen yellowfin tuna (Thunnus albacares), until late stages of decomposition (i.e. 120 h). The results revealed that despite standard refrigeration storage conditions (i.e. 4°C), a diverse and complex spoilage bacteriome developed in the gut and liver. The relative abundance of spoilage bacterial taxa increased rapidly in both organs, representing 82% of the bacterial communities in fresh yellowfin tuna, and less than 30% in brine-frozen tuna. Photobacterium was identified as one of the dominant bacterial genera, and its temporal dynamics were positively correlated with histamine concentration in both gut and liver samples, which ultimately exceeded the recommended sanitary threshold of 50 ppm in edible parts of tuna. The results from this study show that the sanitary risks associated with the consumption of this widely eaten fish are strongly influenced by post-capture storage conditions.

The biosynthesis and incorporation of polyunsaturated fatty acids into phospholipid membranes are unique features of certain marine Gammaproteobacteria inhabiting high-pressure and/or low-temperature environments. In these bacteria, monounsaturated and saturated fatty acids are produced via the classical dissociated type II fatty acid synthase mechanism, while omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) are produced by a hybrid polyketide/fatty acid synthase-encoded by the pfa genes-also referred to as the secondary lipid synthase mechanism. In this work, phenotypes associated with partial or complete loss of monounsaturated biosynthesis are shown to be compensated for by severalfold increased production of polyunsaturated fatty acids in the model marine bacterium Photobacterium profundum SS9. One route to suppression of these phenotypes could be achieved by transposition of insertion sequences within or upstream of the fabD coding sequence, which encodes malonyl coenzyme A (malonyl-CoA) acyl carrier protein transacylase. Genetic experiments in this strain indicated that fabD is not an essential gene, yet mutations in fabD and pfaA are synthetically lethal. Based on these results, we speculated that the malonyl-CoA transacylase domain within PfaA compensates for loss of FabD activity. Heterologous expression of either pfaABCD from P. profundum SS9 or pfaABCDE from Shewanella pealeana in Escherichia coli complemented the loss of the chromosomal copy of fabD in vivo. The co-occurrence of independent, yet compensatory, fatty acid biosynthetic pathways in selected marine bacteria may provide genetic redundancy to optimize fitness under extreme conditions. IMPORTANCE A defining trait among many cultured piezophilic and/or psychrophilic marine Gammaproteobacteria is the incorporation of both monounsaturated and polyunsaturated fatty acids into membrane phospholipids. The biosynthesis of these dif

Anthropogenic activities have contributed to the release of harmful toxicants into the environment which will eventually end up in sediments and soils which are the foundation of food web. Application of instrumental analysis solely is time consuming, costly, and only limited to the concentration. Incorporating a rapid, sensitive, and cheap bioluminescent based bioassay could indicate the toxicity level and reduce analysis time and cost. However, commercially available system uses a test organism with an optimum temperature of 15ºC-25ºC that required an expensive thermostat. In this study, we aim to isolate bioluminescent bacteria with broad range of growth temperature to assess the toxicity of environmental samples. A new bioluminescent bacterium strain was isolated from squid (Loligo duvauceli) and identified as Photobacterium leiognathi strain AK-MIE (AKS01) using 16S rRNA phylogeny analysis. The bacterial culture was grown in a luminescent broth media with different concentrations (0%-0.6%) of peptone, yeast extract, and salt, and a wide range of pH (5.5-8) and temperatures (4ºC-50ºC). Analysis through OFAT showed the best concentrations were at 0.2% of peptone, 0.3% NaCl, and 0.4% yeast extract, at pH 7.5 and temperatures ranging from 22ºC to 33ºC. The optimisation of medium composition was carried out using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) with four parameters employed (NaCl, peptone, yeast extract, and pH). The predicted optimum conditions by RSM (2.76% NaCl, 2.28% peptone, 0.34% yeast extract, and pH 6.83) and ANN (2.21% NaCl, 2.27% peptone, 0.39% yeast extract, and pH 6.94) produced 541,211.80 RLU and 541,986.20 RLU respectively. The coefficient of determination value (R2) for RSM (0.9440) and ANN (0.9934) indicate a high correlation between the experimental and predicted values with ANN showing a superior data fitting capability. The strain was tested with different concentrations of toxicants that showed inhibitive ef

The genus Photobacterium, one of the eight genera included in the family Vibrionaceae, contains 27 species with valid names and it has received attention because of the bioluminescence and pathogenesis mechanisms that some of its species exhibit. However, the taxonomy and phylogeny of this genus are not completely elucidated; for example, P. logei and P. fischeri are now considered members of the genus Aliivibrio, and previously were included in the genus Vibrio. In addition, P. damselae subsp. piscicida was formed as a new combination for former Vibrio damsela and Pasteurella piscicida. Moreover, P. damselae subsp. damselae is an earlier heterotypic synonym of P. histaminum. To avoid these incovenences draft and complete genomic sequences of members of Photobacterium are increasingly becoming available and their use is now routine for many research laboratories to address diverse goals: species delineation with overall genomic indexes, phylogenetic analyses, comparative genomics, and phenotypic inference. The habitats and isolation source of the Photobacterium species include seawater, sea sediments, saline lake waters, and a variety of marine organisms with which the photobacteria establish different relationships, from symbiosis to pathogenic interactions. Several species of this genus contain bioluminescent strains in symbiosis with marine fish and cephalopods; in addition, other species enhance its growth at pressures above 1 atmosphere, by means of several high-pressure adaptation mechanisms and for this, they may be considered as piezophilic (former barophilic) bacteria. Until now, only P. jeanii, P. rosenbergii, P. sanctipauli, and the two subspecies of P. damselae have been reported as responsible agents of several pathologies on animal hosts, such as corals, sponges, fish and homeothermic animals. In this review we have revised and updated the taxonomy, ecology and pathogenicity of several members of this genus. [Int Microbiol 20(1): 1-10 (2017)]Keywords

Gene based methods for identification of species from the Vibrionaceae family have been developed during the last decades to address the limitations of the commonly used 16S rRNA gene phylogeny. Recently, we found that the ferric-uptake regulator gene (fur) can be used as a single identification marker providing species discrimination, consistent with multi-locus sequencing analyses and whole genome phylogenies. To allow for broader and easy use of this marker, we have developed an online prediction service that allows the identification of Vibrionaceae species based on their fur-sequence. The input is a DNA sequence that can be uploaded on the web service; the output is a table containing the strain identifier, e-value, and percentage of identity for each of the matches with rows colored in green for hits with high probability of being the same species. The service is available on the web at: http://www.cbs.dtu.dk/services/furIOS-1.0/. The fur-sequences can be derived either from genome sequences or from PCR-amplification of the genomic region encoding the fur gene. We have used 191 strains identified as Vibrionaceae based on 16S rRNA gene sequence to test the PCR method and the web service on a large dataset. We were able to classify 171 of 191 strains at the species level and 20 strains remained unclassified. Furthermore, the fur phylogenetics and subsequent in silico DNA-DNA hybridization demonstrated that two strains (ATCC 33789 and ZS-139) previously identified as Vibrio splendidus are more closely related to V. tasmaniensis and V. cyclitrophicus, respectively. FurIOS is an easy-to-use online service that allows the identification of bacteria from the Vibrionaceae family at the species level using the fur gene as a single marker. Its simplistic design and straightforward pipeline makes it suitable for any research environment, from academia to industry. Introduction

Vibrionaceae is a large marine bacterial family, which can constitute up to 50% of the prokaryotic population in marine waters. Photobacterium is the second largest genus in the family and we used comparative genomics on 35 strains representing 16 of the 28 species described so far, to understand the genomic diversity present in the Photobacterium genus. Such understanding is important for ecophysiology studies of the genus. We used whole genome sequences to evaluate phylogenetic relationships using several analyses (16S rRNA, MLSA, fur, amino-acid usage, ANI), which allowed us to identify two misidentified strains. Genome analyses also revealed occurrence of higher and lower GC content clades, correlating with phylogenetic clusters. Pan-and core-genome analysis revealed the conservation of 25% of the genome throughout the genus, with a large and open pan-genome. The major source of genomic diversity could be traced to the smaller chromosome and plasmids. Several of the physiological traits studied in the genus did not correlate with phylogenetic data. Since horizontal gene transfer (HGT) is often suggested as a source of genetic diversity and a potential driver of genomic evolution in bacterial species, we looked into evidence of such in Photobacterium genomes. Genomic islands were the source of genomic differences between strains of the same species. Also, we found transposase genes and CRISPR arrays that suggest multiple encounters with foreign DNA. Presence of genomic exchange traits was widespread and abundant in the genus, suggesting a role in genomic evolution. The high genetic variability and indications of genetic exchange make it difficult to elucidate genome evolutionary paths and raise the awareness of the roles of foreign DNA in the genomic evolution of environmental organisms.

Six strains were isolated from the hemolymph of the spider crab Maja brachydactyla, captured in Spain, and one from a diseased blue mussel, Mytilus edulis. The 16S rRNA gene sequences showed close similarity to the recently described Photobacterium swingsii (98.1 %) and to a lesser degree to Photobacterium aquimaris (97.8 %). MLSA analyses showed a monophyletic group including P. swingsii that form a new subclade. All genomic analyses (Average Nucleotide Identity, Average Amino Acid Identity, and in silico DNA–DNA) clearly separate the strains analysed from P. swingsii with values below the thresholds to delimit a new species. The phenotypic, genotypic and genomic data presented here clearly place these strains as a coherent group within the genus Photobacterium, for which we propose the name Photobacterium sanguinicancri sp. nov. Strain CAIM 1827T (=CECT 7579T, =DSM 24670T) is proposed as the type strain of the species

During our search for new natural products from the marine environment, we discovered a wide range of cyclic peptides from a marine Photobacterium, closely related to P. halotolerans. The chemical fingerprint of the bacterium showed primarily non-ribosomal peptide synthetase (NRPS)-like compounds, including the known pyrrothine antibiotic holomycin and a wide range of peptides, from diketopiperazines to cyclodepsipeptides of 500-900 Da. Purification of components from the pellet fraction led to the isolation and structure elucidation of four new cyclodepsipeptides, ngercheumicin F, G, H, and I. The ngercheumicins interfered with expression of virulence genes known to be controlled by the agr quorum sensing system of Staphylococcus aureus, although to a lesser extent than the previously described solonamides from the same strain of Photobacterium.

In Malaysia there are about 180 river basins with about 5% of them severely polluted with toxicants. Current costs of instrument-based monitoring prevent regular toxicity monitoring of these polluted rivers. The global trend is using bioassays coupled with instrumental analysis that dramatically reduces the costs of monitoring. Toxicity bioassays using bioluminescent bacteria provide a rapid and sensitive method to monitor the presence of toxicants in the environment and are now globally accepted as the gold standard in environmental monitoring. Unfortunately, the most popular commercial bioassay system uses a bacterial strain that has a low (15oC) and narrow band of optimal working temperature which requires the use of a refrigerated water bath, preventing field work and near real time results. To solve this problem, a novel bioluminescent bacterium Photobacterium sp. strain MIE has been isolated from Indian mackerel, (Rastrelliger kanagurta). The optimal condition for bioluminescence production of this bacterium occurs within a broad temperature range of 24 to 30°C, allowing for easier application in the field. Other optimal luminescence conditions are incubation at pH 5.5-7.5 with 30-50 g/L of tryptone as the nitrogen source, salinity with 15-20 g/L of sodium chloride and 4 g/L of glycerol as the sole carbon source. Experimental results showed that a bioassay system using this bacterium can be used to detect selected toxicants such as heavy metals, xenobiotics and solvents under a broad range of tropical temperature conditions. Photobacterium sp. strain MIE responded sensitively towards mercury, silver, copper, nickel, zinc and chromium with IC50 values (mg/L) of 0.05, 0.12, 0.85, 12.32, 18.72 and 26.02, respectively. In addition, this bacterium could be used to detect the xenobiotics paraformaldehyde, phenol red, cycloheximide, p-nitroaniline, 2,4-dinitrophenol, 2,6-dichloroindophenol, ethanolamine and sodium dodecyl sulfate with IC50 values 20.70, 15.66, 351.40

La bacteria marina Photobacterium damselae comprende dos subespecies, la subsp. piscicida y la subsp. damselae. Ambas subespecies presentan características fenotípicas claramente diferenciales. Dichas diferencias abarcan desde diferentes temperaturas de crecimiento o rango de hospedadores hasta una gran variabilidad en la composición de los productos extracelulares. Todas las cepas de P. damselae producen sideróforos, y la naturaleza química de los mismos difiere en las dos subespecies. Aunque no hemos podido descifrar la base genética que se esconde tras estos sistemas, sí hemos encontrado genes regulados por hierro. La mutación de los genes fhuE y de la O-metiltransferasa no causó disminución en la capacidad de crecimiento en déficit de hierro, lo que sugiere una redundancia de sus funciones. Cabe destacar que el gen de la O-metiltransferasa se halla regulado fuertemente por la disponibilidad de hierro extracelular a través de la proteína Fur.

Photobacterium comprises several species in Vibrionaceae, a large family of Gram-negative, facultatively aerobic, bacteria that commonly associate with marine animals. Members of the genus are widely distributed in the marine environment and occur in seawater, surfaces, and intestines of marine animals, marine sediments and saline lake water, and light organs of fish. Seven Photobacterium species are luminous via the activity of the lux genes, luxCDABEG. Much recent progress has been made on the phylogeny, genomics, and symbiosis of Photobacterium. Phylogenetic analysis demonstrates a robust separation between Photobacterium and its close relatives, Aliivibrio and Vibrio, and reveals the presence of two well-supported clades. Clade 1 contains luminous and symbiotic species and one species with no luminous members, and Clade 2 contains mostly nonluminous species. The genomes of Photobacterium are similar in size, structure, and organization to other members of Vibrionaceae, with two chromosomes of unequal size and multiple rrn operons. Many species of marine fish form bioluminescent symbioses with three Photobacterium species: Photobacterium kishitanii, Photobacterium leiognathi, and Photobacterium mandapamensis. These associations are highly, but not strictly species specific, and they do not exhibit symbiont-host codivergence. Environmental congruence instead of host selection might explain the patterns of symbiont-host affiliation observed from nature.

Oxygen plays a key role in bacterial bioluminescence. The simultaneous and continuous kinetics of oxygen consumption and light emission during a complete exhaustion of the exogenous oxygen present in a closed system has been investigated. The kinetics are performed with Vibrio fischeri, V. harveyi, and Photobacterium phosphoreum incubated on respiratory substrates chosen for their different reducing power. The general patterns of the luminescence time courses are different among species but not among substrates. During steady-state conditions, substrates, which are less reduced than glycerol, have, paradoxally, a better luminescence efficiency. Oxygen consumption by luciferase has been evaluated to be approximately 17% of the total respiration. Luciferase is a regulatory enzyme presenting a positive cooperative effect with oxygen and its affinity for this final electron acceptor is about 4-5 times higher than the one of cytochrome oxidase. The apparent Michaelis constant for luciferase has been evaluated to be in the range of 20 to 65 nM O2. When O2 concentrations are as low as 10 nM, luminescence can still be detected; this means that above this concentration, strict anaerobiosis does not exist. By n-butyl malonate titration, it was clearly shown that electrons enter the luciferase pathway only when the cytochrome pathway is saturated. It is suggested that, in bioluminescent bacteria, luciferase acts as a free-energy dissipating valve when anabolic processes (biomass production) are impaired.

Han sido estudiadas la catalasa y la superóxido dismutasa (SOD) de bacterias bioluminiscentes marinas. Hemos encontrado varios isoenzimas de catalasa y un isoenzima de superóxido dismutasa y se ha observado que a menor luminiscencia los niveles de catalasa son mayores. Una variante de Photobacterium phosphoreum var. K (cepa mutante que carece de bioluminiscencia) mostró los máximos niveles de catalasa. Hay dos tipos de catalasas en esta estirpe, una de pI 7,2 que es inhibida por el 3-amino, 1,2,4-triazol y otros isoenzimas que son resistentes a la acción de este inhibidor. Todas las catalasas de estas bacterias bioluminiscentes marinas son hemoproteínas, ya que son inhibidas por la azida y el cianuro. El isoenzima de SOD es una Fe-SOD., Catalase and superoxide dismutase (SOD) were studied in strains of marine bioluminescent bacteria. We found several isozymes of catalase in these strains and only one isozyme of superoxide dismutase. We observed that catalase levels rose as bioluminiscence emission fell. A dark strain of Photobacterium phosphoreumvar. K showed the maximun levels of catalase. There are two types of catalases in this strain: an isozyme of pI 7.2 inhibited by 3-amino, 1, 2, 4-triazole and others isozyrnes resistent to this inhibitor. All isozymes of catalase from these bioluminescent marine bacteria are hemo-proteins, since they were inhibited by cianyde and azide. The single isozyme of SOD is a Fe-SOD.

Four marine strains of Vibrio and Photobacterium were tested for their susceptibilities to 22 antimicrobial agents. All strains were susceptible to chloramphenicol, nalidixic acid, cotrimoxazole, tetracycline, netilmicin and norfloxacin; all were resistant to penicillin and ampicillin, and exhibited ß-lactamase activity. However, there were significant differences between strains, especially in their patterns of betalactam and aminoglycosides susceptibility. Vibrio splendidus biovar 1 and Vibrio harveyi have ß-lactamases of the 2d group (cloxacillin-hydrolyzing ß-lactamases), Photobacterium angustum has ß-lactamases of the 2b group (broad-spectrum ß-lactamases inhibited by clavulanic acid), and Photobacterium phosphoreum var. K has ß-lactamases of the 2c group (carbenicillin-hydrolyzing ß-lactamases inhibited by clavulanic acid)., Ha sido estudiada la actividad in vitro de 22 antimicrobianos frente a cuatro cepas de Vibrio y Photobacterium de origen marino. Todas las cepas son susceptibles a cloranfenicol, ácido nalidíxico, cotrimoxazol, tetraciclina, netilmicina y norfloxacina; resistentes a penicilina y ampicilina, y producen ß-lactamasas. Sin embargo, hay diferencias significativas entre las cepas, especialmente en sus patrones de sensibilidad a otros antibióticos betalactámicos y aminoglicósidos. Vibrio splendidus biovar 1 y Vibrio harveyi poseen ß-lactamasas pertenecientes al grupo 2d (ß-lactamasas que hidrolizan la cloxacilina); Photobacterium angustum, ß-lactamasas del grupo 2b (ß-lactamasas de amplio espectro inhibidas por el ácido clavulánico); y Photobacterium phosphoreum var. K, ß-lactamasas del grupo 2c (ß-lactamasas que hidrolizan la carbenicilina y son inhibidas por el ácido clavulánico).

Han sido aisladas bacterias bioluminiscentes en aguas superficiales costeras de la isla de Gran Canaria y en la superficie y el contenido intestinal de Sarpa salpa (Linnaeus, 1758), pez muy común en las islas Canarias. Las especies aisladas fueron Vibrio splendidus biovar 1, Vibrio logei, Vibrio fischeri y Photobacterium phosphoreum. La población de bacterias bioluminiscentes en estas aguas superficiales fluctúa considerablemente, desde 50 000 unidades formadoras de colonias por litro (ufc/l) en los meses de verano a 3 000 ufc/l en invierno. Hemos encontrado una correlación positiva entre la temperatura del agua y el número de bacterias bioluminiscentes., Bioluminescent bacteria were isolated on coastal surface waters, and on the surface and in the gastrointestinal tract of Sarpa salpa (Linnaeus, 1758) (a very common fish in the Canary Islands) off Gran Canaria Island. The species isolated were: Vibrio splendidus biovar 1; Vibrio logei; Vibrio fischeri and Photobacterium phosphoreum. The population of biolumineseent bacteria in these coastal surfaee waters fluctuated considerably, being as high as 50 000 cfu/l in the summer and as low as 3 000 cfu/l in the winter. There is a positive correlation between water temperature and the number of bioluminescent bacteria.

Pseudotuberculosis, caused by the halophilic gram-negative bacterium Photobacterium damselae ssp. piscicida , has been causing high mortality losses in sea bass ( Dicentrarchus labrax L.) farming. In the present thesis, basic and applied studies were performed concerning the humoral immune system of sea bass, as part of the development of an effective vaccine for this pathogen and with the aim to determine the earliest age/weight at which sea bass can be vaccinated against that disease. Therefore, monoclonal antibodies (mAb) against the heavy (±78 kDa; WDI 1) and light (±28 kDa; WDI 2 and WDI 3) chains were successfully produced and used. The Ig characterisation has shown that non-uniformly disulphide cross-linking of monomeric (M r ±210 kDa) and dimeric (M r ±420 kDa) subunits occurs in the polymerisation of the tetrameric form (M r ±840 kDa). The sequence of the Ig L chain allowed all characteristic segments (V, J and C) to be deduced, and could be considered as a L1/G isotype. In addition, it was shown to have a cluster-like genomic organisation. Due to its importance for vaccination with T dependent antigens, the ontogenetic development of sea bass T cell was studied using a mAb (DLT 15) specific for that lymphocyte subpopulation. It was shown that early T cells may originate in a different compartment, further differentiate in the thymus and subsequently migrate to peripheral lymphoid organs. Adult proportions were reached around 137 days post-hatch (dph).Studies with different combinations of the mAb against sea bass Ig did strongly suggest the existence of B cell heterogeneity, expressing at least two heavy and two light chains. The percentage of B cells in the different immunological organs was studied using all the mAb. The combination of WDI 1 and WDI 3 appeared to label all or almost all B cells. As in other teleost species, the sea bass head kidney appears to be the primary organ for B-lymphocyte differentiation. The proportion of sIg + (B) cells in the

An evaluation of several biological monitoring techniques for hazard assessment of potentially contaminated effluent was conducted at the Aberdeen Proving Ground-Edgewood Area Wastewater Treatment Plant (APG-EA WWTP), Aberdeen Proving Ground, MD, from January 1989 to December 13, 1989. An array of biomonitoring tests structured in a tiered hazard assessment framework was used in the evaluation of the effluent. Several levels of biological organization were included in the array of tests. Acute toxicity was evaluated on 24-h composite samples using a 15-min Microtox R assay which employs microbial (Photobacterium phosphoreum) bioluminescent activity. Two 24-h LC50 rotifer (Brachionus rubens) toxicity tests were conducted using 24-h composite samples The following chronic tests were all performed two times using 24-h composite samples: 96-h EC50 algal (Selenastrum capricornutum) growth test, 7-d daphnid (Ceriodaphnia dubia) survival and reproduction test, and 7-d fathead minnow (Pimephales promelas) survival and growth test. Generally, the acute rotifer tests and all chronic tests were conducted during the same periods in order to compare toxicological responses between biomonitoring systems.... Wastewater, Aquatic, Acute toxicity, Chronic toxicity, Mutagenicity, Ames, Teratogenicity, FETAX, Carcinogenicity, Ventilatory biomonitoring system, Microtox R, Photobacterium., See also Volume 2, ADA260226. Prepared in cooperation with Maryland Univ. Systems, Wye Research and Education Center, Queenstown, MD. Available as Rept. no. WREC-92-B6.

All naturally occurring isolates of all five species of the marine genus Photobacterium have β-lactamase activity. In this study, the β-lactamase from the laboratory strain P. leiognathi 206 is fully characterised. The enzyme is constitutive and is released from the cell by osmotic shocking techniques, suggesting a periplasmic location. The enzyme is maximally active at pH 6.2 and has over 90% maximum activity at pH 7.0. The hydrolytic activity of the β-lactamase is independent of zinc ion presence. On the basis of substrate profile and inhibition studies the β-lactamase is classified as a Richmond and Sykes Class II enzyme. Crypticity tests indicated that there is no outer membrane permeability barrier to β-lactam substrates. Comparative substrate profiles performed with the β-lactamases from three strains of each species of Photobacterium, indicate that the enzymes from strains of P. leiognathi, P. angustum and P. phosphoreum are active only on penicillins, whereas those from P. fischeri and P. logei also hydrolyze cephalosporins. This division is in agreement with an imminent taxonomic change for the latter two species. Analytical iso-electric focusing of the β-lactamases from 45 Photobacterium strains resulted in pI values which were not necessarily species specific and there was little correlation between the pI of the β-lactamase and its substrate profile, excepting the enzymes from P. angustum and P. logei. Although plasmid DNA is present in many Photobacterium strains, conjugative transfer of β-lactamase activity from six different Photobacterium donors to a restrictionless Escherichia coli mutant was not observed. All attempts to 'cure' the bacteria of β-lactamase activity with five different curing agents, were also unsuccessful. A chromosomal location for the β1a+ gene is postulated.

The study addresses the ability of luminous bacteria Photobacterium leiognathi Boisvert et al. and Photobacterium phosphoreum (Cohn) Beijerinck to synthesize polyesters of hydroxycarbon acids (polyhydroxyalkanoates, PHAs) as storage macromolecules. The screened strains widely vary in their PHA productivity. Ph. leiognathi (but not Ph. phosphoreum) produces PHAs containing monomers of 3-hydroxyvaleric acid and, in some cases, 3-hydroxyhexanoic acid, in addition to common monomers of 3-hydroxybutyric acid. All studied strains of Ph. phosphoreum produce pure poly-3-hydroxybutyrate only. In the case of Ph. leiognathi, addition of valeric acid as substrate can increase the amounts of medium-chain-length hydroxy acids contained in the produced polymers. The results suggest a conclusion that luminous microorganisms of Photobacterium genus can be considered as producers of multi-component PHAs, Исследована способность светящихся бактерий видов Photobacterium leiognathi Boisvert et al. и Photobacterium phosphoreum (Cohn) Beijerinck к синтезу полиэфиров гидроксикарбоновых кислот (полигидроксиалканоатов – ПГА) в качестве резервных макромолекул. Исследованные штаммы значительно различались по их способности к синтезу ПГА. Ph. leiognathi (но не Ph. phosphoreum) синтезировал ПГА, которые, помимо мономеров поли-3-гидроксибутирата, содержали мономеры 3-гидроксивалериановой и, иногда 3-гидроксикапроновой кислот. Все изученные штаммы Ph. phosphoreum образуют только гомополимерный поли-3-гидроксибутират. В случае Ph. leiognathi добавление валериановой кислоты в качестве субстрата может увеличивать содержание 3-гидроксивалериановой и 3-гидроксикапроновой кислот в полимере. Результаты позволяют рассматривать светящиеся микроорганизмы рода Photobacterium в качестве продуцентов многокомпонентных ПГА

The study addresses the ability of luminous bacteria Photobacterium leiognathi Boisvert et al. and Photobacterium phosphoreum (Cohn) Beijerinck to synthesize polyesters of hydroxycarbon acids (polyhydroxyalkanoates, PHAs) as storage macromolecules. The screened strains widely vary in their PHA productivity. Ph. leiognathi (but not Ph. phosphoreum) produces PHAs containing monomers of 3-hydroxyvaleric acid and, in some cases, 3-hydroxyhexanoic acid, in addition to common monomers of 3-hydroxybutyric acid. All studied strains of Ph. phosphoreum produce pure poly-3-hydroxybutyrate only. In the case of Ph. leiognathi, addition of valeric acid as substrate can increase the amounts of medium-chain-length hydroxy acids contained in the produced polymers. The results suggest a conclusion that luminous microorganisms of Photobacterium genus can be considered as producers of multi-component PHAs, Исследована способность светящихся бактерий видов Photobacterium leiognathi Boisvert et al. и Photobacterium phosphoreum (Cohn) Beijerinck к синтезу полиэфиров гидроксикарбоновых кислот (полигидроксиалканоатов – ПГА) в качестве резервных макромолекул. Исследованные штаммы значительно различались по их способности к синтезу ПГА. Ph. leiognathi (но не Ph. phosphoreum) синтезировал ПГА, которые, помимо мономеров поли-3-гидроксибутирата, содержали мономеры 3-гидроксивалериановой и, иногда 3-гидроксикапроновой кислот. Все изученные штаммы Ph. phosphoreum образуют только гомополимерный поли-3-гидроксибутират. В случае Ph. leiognathi добавление валериановой кислоты в качестве субстрата может увеличивать содержание 3-гидроксивалериановой и 3-гидроксикапроновой кислот в полимере. Результаты позволяют рассматривать светящиеся микроорганизмы рода Photobacterium в качестве продуцентов многокомпонентных ПГА