Taxonomy of Marine Bacteria: the Genus Beneckea

One-hundred-and-forty-five isolates of marine origin were submitted to an extensive physiological, nutritional, and morphological characterization. All strains were gram-negative, facultatively anaerobic, straight or curved rods which were motile by means of flagella. Glucose was fermented with the production of acid but no gas. Sodium but no organic growth factors were required. None of the strains were able to denitrify or fix molecular nitrogen. The results of nutritional and physiological tests were submitted to a numerical analysis. On the basis of phenotypic similarity, nine groups were established. These groups could be distinguished from one another by multiple, unrelated, phenotypic traits. Six groups which had deoxyribonucleic acid (DNA) containing 45 to 48 moles per cent guanine plus cytosine (GC) were assigned to a redefined genus Beneckea. All of the strains in this genus, when grown in liquid medium, had a single, polar flagellum. When grown on a solid medium, many strains had peritrichous flagella. Two groups were similar to previously described species and were designated B. alginolytica and B. natriegens. The remaining four groups were designated B. campbellii, B. neptuna, B. nereida, and B. pelagia. An additional group of phenotypically similar strains having the properties of the genus Beneckea was not included in the numerical analysis. These strains were readily separable from species of this genus and were designated B. parahaemolytica. Of the remaining groups, one was identified as Photobacterium fischeri. The other group (B-2) which had about 41 moles% GC content in its DNA could not be placed into existing genera.     

Taxonomy of Marine Bacteria: Beneckea nigrapulchrituda sp. n

Fourteen bacterial strains of marine origin, which formed colonies containing crystals of a blue-black pigment, were submitted to a morphological, physiological, and nutritional characterization. The results indicated that these organisms form a new species of the genus Beneckea.     

昆虫病原线虫共生菌的分类

昆虫病原线虫共生菌是存在于昆虫病原线虫肠道内的一类细菌 ,属肠杆菌科 (Enterobacteriaceae) ,兼性厌氧 ,包括致病杆菌属 (Xenorhabdus) [1] 和光杆状菌属 (Photorhabdus) [2 ] ,它们分别与斯氏线虫属 (Stein ernema)和异小杆线虫属 (Heterorhabditis)的线虫共生[3] 。在自然界 ,共生菌存在于 3龄侵染期线虫的肠道中[4 ] ,不能从土壤中分离获得 ,是昆虫病原线虫的主要致病因子。昆虫病原线虫共生菌直到 2 0世纪 5 0年代末期才被发现 ,其分类地位也经常发生变动 ,鉴定工作尽管几十年来陆陆续续时有报道 ,但并不十分深入和系统。近年来 ,…     

Taxonomy of Aerobic Marine Eubacteria

Two hundred and eighteen strains of nonfermentative marine bacteria were submitted to an extensive morphological, physiological, and nutritional characterization. All the strains were gram-negative, straight or curved rods which were motile by means of polar or peritrichous flagella. A wide variety of organic substrates served as sole sources of carbon and energy. The strains differed extensively in their nutritional versatility, being able to utilize from 11 to 85 carbon compounds. Some strains had an extracellular amylase, gelatinase, lipase, or chitinase and were able to utilize n-hexadecane and to denitrify. None of the strains had a yellow, cell-associated pigment or a constitutive arginine dihydrolase system, nor were they able to hydrolyze cellulose or agar. The results of the physiological and nutritional characterization were submitted to a numerical analysis which clustered the strains into 22 groups on the basis of phenotypic similarities. The majority of these groups were separable by a large number of unrelated phenotypic traits. Analysis of the moles per cent guanine plus cytosine (GC) content in the deoxyribonucleic acid of representative strains indicated that the peritrichously flagellated groups had a GC content of 53.7 to 67.8 moles%; polarly flagellated strains had a GC content of 30.5 to 64.7 moles%. The peritrichously flagellated groups were assigned to the genus Alcaligenes. The polarly flagellated groups, which had a GC content of 43.2 to 48.0 moles%, were placed into a newly created genus, Alteromonas; groups which had a GC content of 57.8 to 64.7 moles% were placed into the genus Pseudomonas; and the remaining groups were left unassigned. Twelve groups were given the following designations: Alteromonas communis, A. vaga, A. macleodii, A. marinopraesens, Pseudomonas doudoroffi, P. marina, P. nautica, Alcaligenes pacificus, A. cupidus, A. venustus, and A. aestus. The problems of assigning species of aerobic marine bacteria to genera are discussed.     

Isolation of Bacteriophages of the Marine Bacterium Beneckea natriegens from Coastal Salt Marshes

Bacteriophages of the marine bacterium Beneckea natriegens were isolated from coastal marshes where they were limited to brackish and marine waters. The phages were widely distributed and morphologically diverse in the marshes.     

Marine Nematode Taxonomy in Africa: Promising Prospects Against Scarcity of Information

From the late 19th century, Africa has faced heavy exploitation of its natural resources with increasing land/water pollution, and several described species have already become extinct or close to extinction. This could also be the case for marine nematodes, which are the most abundant and diverse benthic group in marine sediments, and play major roles in ecosystem functioning. Compared to Europe and North America, only a handful of investigations on marine nematodes have been conducted to date in Africa. This is due to the scarcity of experienced taxonomists, absence of identification guides, as well as local appropriate infrastructures. A pivotal project has started recently between nematologists from Africa (Tunisia), India, and Europe (Italy) to promote taxonomic study and biodiversity estimation of marine nematodes in the African continent. To do this, as a first step, collection of permanent slides of marine nematodes (235 nominal species and 14 new to science but not yet described) was recently established at the Faculty of Sciences of Bizerte (Tunisia). Capacity building of next generation of African taxonomists have been carried out at level of both traditional and molecular taxonomy (DNA barcoding and next-generation sequencing [NGS]), but they need to be implemented. Indeed, the integration of these two approaches appears crucial to overcome lack of information on the taxonomy, ecology, and biodiversity of marine nematodes from African coastal waters.     

Phytol Degradation by Marine Bacteria

Microbial degradation of phytol is often proposed to be the primary source of the acyclic isoprenoid acids observed in sediments, yet only a limited number of these acids have been found in bacterial cultures grown on phytol. This study reports detailed capillary gas chromatography and gas chromatography-mass spectrometry analyses of the products resulting from growth of marine bacteria on phytol as the sole carbon source. We examined two strains of bacteria which were able to oxidize phytol to phytenic acid but were unable to further degrade phytol. The third isolate studied converted phytol to a mixture of five saturated isoprenoid acids. The C₁₇ isoprenoid acid produced was of particular interest, since its genesis from phytol would have involved several unusual intermediates. It is suggested that this acid is produced by bacterial metabolism of the C₁₈ isoprenoid ketone (produced from phytol abiologically under oxic conditions) and that its abundance is thus a sensitive indicator of sedimentary depositional conditions.     

Extractable Lipids of Gram-Negative Marine Bacteria: Phospholipid Composition

Phospholipid compositions of 20 strains of marine and estuarine bacteria were determined. Results showed that phospholipids of marine bacteria differed very little from those of nonmarine organisms with phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol being the predominant phospholipids in all strains examined. Lyso-phosphatidylethanolamine occurred in significant quantities among a number of the marine bacteria, and two of the isolates contained significant quantities of poly-beta-hydroxybutyrate. Effects of age and growth temperature on the phospholipid composition were also investigated. It is suggested that phylogenetic relationships among bacteria may be correlated with phospholipid composition.     

Collagenolytic Activity of Some Marine Bacteria

Reconstituted, acid-extracted collagen was used to prepare a medium to screen proteolytic marine bacteria for their ability to elaborate collagenolytic enzymes. The medium was resistant to solubilization by trypsin, hyaluronidase, chondroitinase ABC, and various marine proteinases, but was readily hydrolyzed by commercial Clostridium collagenases. Eighty-seven marine isolates collected in the vicinity of Bermuda, Oahu (Hawaii), and Stone Harbor and Cape May, N. J., were screened. Approximately 44 per cent of the isolates were capable of elaborating enzymes that hydrolyzed reconstituted collagen gels. Several cultures produced collagenolytic enzymes only when grown in the presence of collagen or degradation products of collagen, and with very few exceptions the presence of collagen in the medium greatly enhanced collagenolytic enzyme production. The enzymes from a collagenolytic Bermuda marine isolate were studied in more detail to illustrate that the enzymes capable of hydrolyzing reconstituted collagen were separable from nonspecific proteinases by zone electrophoresis and that these enzymes were true collagenases by virtue of their ability to hydrolyze native bovine Achilles'tendon obtained from three different sources.     

Bioactive Compounds from Marine Bacteria and Fungi

Marine bacteria and fungi are of considerable importance as new promising sources of a huge number of biologically active products. Some of these marine species live in a stressful habitat, under cold, lightless and high pressure conditions. Surprisingly, a large number of species with high diversity survive under such conditions and produce fascinating and structurally complex natural products. Up till now, only a small number of microorganisms have been investigated for bioactive metabolites, yet a huge number of active substances with some of them featuring unique structural skeletons have been isolated. This review covers new biologically active natural products published recently (2007–09) and highlights the chemical potential of marine microorganisms, with focus on bioactive products as well as on their mechanisms of action.     

Distribution, Taxonomy, and Boring Patterns of Marine Endolithic Algae

Penetration of calcareous substrates by algae involves differentmicroenvironments. Endolithic algae include two different lifeforms: (1) algae colonizing existing spaces within the rock,and (2) algae actively boring within the carbonate substrate. Two species of boring Cyanophyta were studied, and their boringswere compared in exposed calcite (Island spar). The size andpattern of borings reflect the corresponding properties of thealgae and show taxonomic distinctions. The direction of thetunnels and their wall sculptureare determined by the planesof crystal cleavage and twinning. Algal boring is a dissolution process performed by the terminalcells of endolithic filaments. The space dissolved away by analga has the shape of a miniature calcite crystal. Dissolutionproceeds along the crystal twinning lines diagonally to theprevious microcrystal space. Thetunnel represents a sequenceof such microcrystal-shaped spaces. Both biological and mineralogicaldeterminants should be considered in the interpretation of algalboring patterns.     

醋酸菌多相分类研究进展

醋酸菌是一大群革兰氏染色阴性、绝对好氧的细菌的总称, 能将乙醇或糖类不完全氧化为有机酸。醋酸菌的分类在近30年经历了很大变化, 早期的分类系统主要以表型和生化特征为基础。如今, 大多采用结合表型、化学分类法和基因型数据的多相分类法对醋酸菌进行分类。本文综述了醋酸菌的多相分类研究进展, 主要介绍了醋酸菌的现行分类情况及表型分类、化学分类和基因分型等方法在醋酸菌分类中的应用。     

Tryptophanase-Positive Bacteria in the Marine Environment

The prevalence of indole-positive organisms in the gut and environment of marine animals was studied. Indole formation by a group of the isolates was found to occur only in the presence of tryptophan. The isolates examined were all assigned to the genus Vibrio.     

Nitrogen Fixation by Marine Photosynthetic Bacteria

S ummary . Potential nitrogen-fixing marine photosynthetic bacteria isolated from the coastal waters and sea-bed sediments of Cardigan Bay and adjoining mud flats, were investigated, using the acetylene reduction technique, to ascertain the magnitude of their contribution of fixed nitrogen to the coastal ecosystem. Aberystwyth harbour and Iceland fjord mud readily yielded Athiorhodaceae, the majority of which consistently reduced acetylene when grown as pure cultures on marine media. Only one such strain was isolated from local seawater, but they were more common in Iceland fjord water. No marine Thiorhodaceae were isolated. It was essential to monitor crude and pure culture systems for ethylene production in the absence of acetylene.     

Properties of Alginate Lyases from Marine Bacteria

Alginate lyases (EC 4.2.2.3) from two marine bacteria were isolated and partially characterized. A cell-bound lyase from isolate A3 had a molecular weight of approximately 100,000 and cleaved mannuronate blocks, apparently in an exo manner. A lyase recovered from the culture medium of isolate W3 was soluble in saturated ammonium sulfate, cleaved guluronate blocks, apparently in an endo manner, and had a molecular weight of 35,000. The thiobarbiturate test and urea-polyacrylamide gel electrophoresis were used to determine substrate specificity and mode of substrate cleavage by the enzymes.