Photobacterium Species Research Articles

The effects of phosphate on the structure and stability of the luciferases from [formula omitted

The luciferases from three very distinct species of luminous bacteria, Beneckea , harveyi , Photobacterium , fischeri , and, Photobacterium , phosphoreum , bind phosphate and other anions to form complexes with decreased sensitivity to proteases and increased thermal stability. Upon treatment with either trypsin or chymotrypsin in either low phosphate or high phosphate buffers, the rate of loss of activity of all three luciferases is the same as the rate of bond cleavage within a discrete region of the α subunit. Unlike the enzyme from B. , harveyi , the β subunits of the enzymes from the Photobacterium species are sensitive to the proteases in low phosphate, while in high phosphate, the β subunits of all three luciferases are not sensitive to trypsin or chymotrypsin.

Halophilic vibrios in human tissue infections

Vibrios that need 0.07-0.4 M Na + for growth in vitro are common in inshore sea waters, especially in the summer. Assimilation tests differentiate 11 species and a heterogenous group of the genus Beneckea. and 3 species of the genus Photobacterium. One species, B. parahaemolyticus. has been implicated for some years in food-poisoning. This species and B. alginolyticus and the lactose-fermenting B. vulnificus have been isolated from human tissue infections in the northern hemisphere, with a few cases in Australia. We isolated 16 strains of the 3 species from routine swabs of ear and wound infections, pneumonia and salpingitis, identified them using the ‘expanded’ API 20E kit plus NaCl tolerance. The species were confirmed by assimilation tests. Vibrios that need 0.07-0.4 M Na + for growth in vitro are common in inshore sea waters, especially in the summer. Assimilation tests differentiate 11 species and a heterogenous group of the genus Beneckea. and 3 species of the genus Photobacterium. One species, B. parahaemolyticus. has been implicated for some years in food-poisoning. This species and B. alginolyticus and the lactose-fermenting B. vulnificus have been isolated from human tissue infections in the northern hemisphere, with a few cases in Australia. We isolated 16 strains of the 3 species from routine swabs of ear and wound infections, pneumonia and salpingitis, identified them using the ‘expanded’ API 20E kit plus NaCl tolerance. The species were confirmed by assimilation tests.

Proteolytic sensitivity of the α subunit in luciferases ofPhotobacterium species

Bacterial luciferases isolated from strains of three species ofPhotobacterium (P. leiognathi, P. phosphoreum andP. fischeri) have been found to be considerably more sensitive to trypsin inactivation than luciferase fromBeneckea harveyi. P. leiognathi luciferase has a pseudo-first-order rate constant of inactivation of 0.14 min−1 when exposed to 1 μg/ml (42 nM) trypsin. As judged by sodium dodecyl sulfate electrophoresis of the products of proteolysis, only the α subunit of the αβ heterodimeric luciferases ofPhotobacterium species was attacked by trypsin. After treatment of these enzymes with trypsin, the β subunit of eachPhotobacterium species retained its ability to reform active luciferase when renatured with native complementary α subunit.

Electrophoretic mobilities of superoxide dismutases from species ofPhotobacterium, beneckea, vibrio, and selected terrestrial enterobacteria

Cell-free extracts of 93 strains from 23 species and biotypes ofPhotobacterium, Beneckea, andVibrio were electrophoresed on polyacrylamide gels and then stained for superoxide dismutase (SOD) activity. All strains exhibited a single activity band with the exception ofPhotobacterium leiognathi, which had one major and two minor bands. Strains representative of all three genera were found to have SOD activities that were sensitive to treatment with H2O2, suggesting that they were iron-containing enzymes. Examination of the effect of gel concentration on relative mobility (Rm) suggested that all the iron-containing SODs had very similar molecular weight. Most species could be distinguished on the basis of differences in the Rm values of their SODs.Vibrio was readily separable fromBeneckea andPhotobacterium. A limited electrophoretic analysis of the SODs fromAeromonas, Serratia, Proteus, Erwinia, and other species of terrestrial enterobacteria indicated groupings that were in agreement with previous studies.

Low oxygen is optimal for luciferase synthesis in some bacteria. Ecological implications.

The synthesis of the bioluminescent systems in many strains of two species of the genus Photobacterium which were isolated as symbionts is greater at low oxygen concentrations, where aerobic growth is blocked. In strains of two other species, one Photobacterium of symbiotic orgin, and one (genus Beneckea) whose lent response is observed. At low oxygen concentrations, where there is an inhibition of growth, there is also a similar decrease in the synthesis of the luminescent system. These species-specific differences may indicate important ecological differences along with distinctive differences in the molecular control mechanisms involved in the synthesis of luciferase.

Characterization of luminescent bacteria from the light organs of the Australian pine cone fish (Cleidopus gloriamaris)

Characterization of 13 isolates of luminescent bacteria from specimens of Cleidopus gloriamaris has revealed differences between these organisms and previously described species of Photobacterium. Further studies on the biochemical and serological attributes of these and other luminescent bacteria are essential, before ecological studies on the fish-microbe symbiosis are possible.

The classification of luminescent bacteria

The luminescent bacteria are logically placed in two genera. The common coccoid and frequently non-motile species placed byBeije-rinck first in his genusPhotobacterium, 1889 under the namePhotobacterium phosphorescens syn.Bacterium phosphorescens Fischer, should be recognized as the type species ofPhotobacterium. Other characters indicate that this genus should be placed in the FamilyPseudomonadaceae Winslowet al.. and should include other straight, rod-shaped, luminescent, polar flagellate bacteria that ferment glucose without, however, necessarily producing gas (H2 and CO2) as does the type species. The species that have the form of vibrios should be accepted as members of the genusVibrio as suggested by several previous investigators. They have characters much like those ofVibrio comma, the type species of the genusVibrio.