Cellulolytic activity of luminous bacteria

Summary The luminous bacteriaVibrio harveyi andV. fischeri degrade cellulose. Cellulase activity was high when carboxymethyl cellulose and cellobiose were used as substrates but low with cellulose powder. The role of these microbes in the digestion of food material in fish gut is also discussed.

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Resumen Las bacterias luminosasVibrio harveyi yV. fischeri degradan celulosa. La actividad celulásica fue alta cuando se utilizó Carboxy-metil-celulosa o celobiosa como sustrato y baja cuando se utilizó polvo de celulosa. Se discute el papel de estos microorganismos en la digestión intestinal de los alimentos en peces.

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Résumé Les bactéries lumineusesVibrio harveyi etV. fischeri dégradent la cellulose. L'activité cellulolytique était élevée lorsque la carboxméthylcellulose et la cellobiose servaient de substrats, mais elle était faible avec la poudre de cellulose. On discute également de rôle de ces microorganismes dans la digestion du matériau alimentaire.

     

Permeability studies on luminous bacteria

Summary The changes in light intensity of suspensions of a luminous bacterium in solutions of different electrolytes and non-electrolytes have been watched using an electronic photometer. The rapidity of the gradual extinction of the light was used as an approximate measure of the rapidity of penetration of the substances tested.The results concerning non-electrolytes and amino-acids are summarized in Table 10. (TheP _r -values of this table represent only quite crude estimations of the permeability.)The permeability towards both cations and anions seems to be very small.On the whole, the permeability properties of the bacterium studied seem fairly similar to those of the cells of higher plants.This investigation has been supported by a grant from The State Scientific Council. The author is indebted to Dr. Veijo Wartiovaara for valuable suggestions and to Mr. Sverker Norrback for careful technical assistance.     

Flavin mononucleotide reductase of luminous bacteria

NAD(P)H: FMN oxidoreductase (flavin reductase) couples in vitro to bacterial luciferase. This reductase, which is also postulated to supply reduced flavin mononucleotide in vivo as a substrate for the bioluminescent reaction, has been partially purified and characterized from two species of luminous bacterial. From Photobacterium fischeri the enzyme has a M. W. determined by Sephadex gel filtration, of 43,000 and may have a subunit structure. The turnover number at 20 degrees C, based on a purity estimate of 20 percent, is 1.7 times 10-4 moles of NADH oxidized per min per mole of reductase. The reductase isolated from Beneckea harveyi has an apparent molecular weight of 23,000; its purity was too low to permit estimation of specific activity. Using a spectrophotometric assay at 340 nm with the P. fischeri reductase, both NADH (Km, 8 times 10-5 M) and NADPH (Km, 4 times 10-4 M) were enzymatically oxidized, the Vmax with NADH being approximately twice that of NADPH. Of the flavins tested in this assay, only FMN (Km, 7.3 times 10-5 M) and FAD (Km, 1.4 times 10-4 M) were effective, FMN having a Vmax three times that of FAD. In the coupled assay, i.e., measuring the bioluminescence intensity of the reaction with added luciferase, the optimum FMN concentration was nearly 100 times less than in the spectrophotometric assay. The studies reported suggest the existence of a functional reductase-luciferase complex.     

The cytochromes of luminous bacteria and their coupling to bioluminescence

Vibrio fischeri andV. harveyi possess cytochromes a, b, and c, whereasPhotobacterium leiognathi andP. phosphoreum also contain cytochrome d. In all, cytochrome a as well as some of c binds carbon monoxide. Carbon monoxide does not inhibit bioluminescence (in vivo or in vitro), but carbonyl cyanidem-chlorophenylhydrazone inhibits only in vivo bioluminescence. This inhibition is due to dissipation of the proton motive force which indirectly inhibits bioluminescence by interruption of aldehyde recycling. Bioluminescence is thereby indirectly coupled to the proton motive force.     

Taxonomy of the marine,luminous bacteria

Summary One hundred and seventy-three strains of marine, luminous bacteria isolated from sea water, surfaces and intestines of fish, as well as from the luminous organs of fish and squid were submitted to an extensive phenotypic characterization. A numerical analysis of the results grouped these strains into four clusters which were formed on the basis of overall phenotypic similarity. One cluster, which was given the designationBeneckea harveyi, consisted of strains which had a moles% GC content in their DNAs of 46.5±1.3 and a single, sheathed, polar flagellum when grown in liquid medium. Most of these strains had unsheathed, peritrichous flagella in addition to the sheathed, polar flagellum when grown on solid medium. The two phenotypically similar clusters which were assigned the species designationsPhotobacterium phosphoreum andP. mandapamensis consisted of strains which had 1–3 unsheathed, polar flagella and moles % GC contents in their DNAs of 41.5±0.7 and 42.9±0.5, respectively. The cluster designatedP. fischeri contained strains having 2–8 sheathed, polar flagella and a moles % GC content of 39.8±1.1. These four species could be further distinguished on the basis of a number of nutritional properties as well as other phenotypic traits. The assignment of the luminous, marine bacteria to four species was supported by differences in the properties of the luminous system as well as differences in the pattern of regulation of spartokinase activity which are discussed. The speciesB. harveyi was found to be phenotypically similar to a number of previously characterized, non-luminous strains ofBeneckea which should probably be assigned to this species.Non-Standard Abbreviations ASW artificial sea water - ATCC American Type Culture Collection - BM basal medium - BMA basal medium agar - GC guanine plus cytosine - LA luminous medium agar - LB luminous medium broth - MA Difco Marine Agar - NCMB National Collection of Marine Bacteria - PHB poly--hydroxybutyrate - S similarity coefficient - YEB yeast extract broth This paper is part of a dissertation submitted by the senior author to the Graduate Division of the University of Hawaii in partial fulfillment of the requirements for the Ph.D. Degree in Microbiology     

Carbohydrate specificity of lectins from luminous bacteria

The presence of lectins on a cell surface was demonstrated for 70 cultures of luminous bacteria using hemagglutination reactions. It was shown that hemagglutination of luminous bacteria is inhibited by glucose, maltose, fructose, mannose, and N-acetyl-D-glucosamine. The differences in the inhibition of hemagglutination of luminescent and nonluminescent (spontaneous mutants) symbiotic cultures by N-acetyl-D-galactosamine were revealed. The fact that N-acetyl-D-galactosamine inhibits hemagglutination of the luminescent symbiotic bacteria but does not inhibit hemagglutination of the symbiotic cultures lacking luminescence suggests that lectins with N-acetyl-D-galactosamine specificity are possibly involved in the formation and functioning of the symbiosis of luminous bacteria with marine animals possessing luminous organs.     

Contribution by symbiotically luminous fishes to the occurrence and bioluminescence of luminous bacteria in seawater

Seawater samples from a variety of locations contained viable luminous bacteria, but luminescence was not detectable although the system used to measure light was sensitive enough to measure light from a single, fully induced luminous bacterial cell. When the symbiotically luminous fishCleidopus gloriamaris was placed in a sterile aquarium, plate counts of water samples showed an increase in luminous colony-forming units. Luminescence also increased, decreasing when the fish was removed. Light measurements of water samples from a sterile aquarium containingPhotoblepharon palpebratus, another symbiotically luminous fish, whose bacterial symbionts have not been cultured, showed a similar pattern of increasing light which rapidly decreased upon removal of the fish. These experiments suggest that symbiotically luminous fishes release brightly luminous bacteria from light organs into their environment and may be a source of planktonic luminous bacteria. Although planktonic luminous bacteria are generally not bright when found in seawater, water samples from environments with populations of symbiotically luminous fish may show detectable levels of light.     

Growth inhibition of bacteria by tributylgermanium acetate and its reversal by blood constituents

Growth inhibition ofMycobacterium phlei by tributylgermanium acetate can be reversed by addition of large amounts of blood or blood serum to the nutrient medium; the blood erythrocyte fraction is inactive.On the other hand growth inhibition of the lactic acid bacteriaStreptococcus lactis andLeuconostoc mesenteroides can be counteracted by traces of blood or its crythrocyte fraction, by hemin and by catalase. Blood serum even in large amounts is ineffective.Whereas tributylgermanium acetate is highly active against most lactic acid bacteria studied, the antagonistic action of blood or hemin is found only with the species named. The possible mechanism of this antagonism is discussed.     

The absence of a correlation between plasmids and luminescence in marine luminous bacteria

Members of four species of marine luminous bacteria were examined for the presence of plasmids using gel electrophoresis of purified alkaline extracts. One to four plasmids, with molecular weights ranging from 5 to 120 megadaltons, were found to occur in 43% of the 58 bioluminescent strains examined. There was, thus, no correlation between the presence and absence of plasmids and luminescence, nor was there any single size of plasmid common to the different bacterial species. Spontaneous dark (dim) mutants were selected from five strains ofVibrio (Beneckea) harveyi; in no case was there any difference in the plasmid content between the bright parent strain and the dim isolate.