Factors affecting polyhydroxybutyrate biosynthesis in the marine photosynthetic bacteriumRhodopseudomonas sp. strain W-1S

Applied Biochemistry and Biotechnology - A marine photosynthetic bacterium,Rhodopseudomonas sp. strain W-1S, accumulated polyhydroxybutyrate (PHB) to 56% of the dry cell weight under microaerobic...     

Emulsification potential of a newly isolated biosurfactant-producing bacterium, Rhodococcus sp. strain TA6

An indigenous biosurfactant producing bacterium, Rhodococcus sp. strain TA6 was isolated from Iranian oil contaminated soil using an efficient enrichment and screening method. During growth on sucrose and several hydrocarbon substrates as sole carbon source, the bacterium could produce biosurfactants. As a result of biosurfactant synthesis, the surface tension of the growth medium was reduced from 68mNm(-1) to values below 30mNm(-1). The biosurfactant was capable of forming stable emulsions with various hydrocarbons ranging from pentane to light motor oil. Preliminary chemical characterization revealed that the TA6 biosurfactant consisted of extracellular lipids and glycolipids. The biosurfactant was stable during exposure to high salinity (10% NaCl), elevated temperatures (120°C for 15min) and within a wide pH range (4.0-10.0). The culture broth was effective in recovering up to 70% of the residual oil from oil-saturated sand packs which indicates the potential value of the biosurfactant in enhanced oil recovery.     

Improvement of substrate conversion to molecular hydrogen by three-stage cultivation of a photosynthetic bacterium,Rhodovulum sulfidophilum

In photosynthetic bacteria, after transition to light-anaerobic and nitrogen-deficient conditions, hydrogen evolution starts with expression of nitrogenase activity. Until the expression of enough activity,Rhodovulum sulfidophilum consumed substrates and converted them to poly(3-hydrox-ybutyrate) (PHB), resulting in a decrease in the proportion of substrate converted into hydrogen gas. To prevent conversion to PHB during the period when nitrogenase activity is derepressed, the authors employed a cultivation method consisting of three stages: cell growth, nitrogenase derepression, and hydrogen production. Cells cultivated by this method exhibited no lag time before the commencement of hydrogen evolution and gave an improved yield of hydrogen from the algal fermentative products.     

Barbaloin stimulates growth of Eubacterium sp. strain BAR, a barbaloin-metabolizing bacterium from human feces

Eubacterium sp. strain BAR, isolated from human feces, transformed barbaloin to aloe-emodin anthrone in a basal medium lacking carbohydrate. Barbaloin remarkably stimulated the growth of strain BAR in the basal medium, the stimulative extent of the growth depending on the amount of barbaloin added. The addition of D-glucose, D-galactose, maltose, cellobiose, sucrose or D-amygdalin to the basal medium containing barbaloin caused a decrease of the growth stimulated by barbaloin to the growth level with each sugar, resulting in a complete inhibition of the barbaloin transformation. On the other hand, the addition of D-fructose, which itself stimulated the growth of strain BAR, further increased the growth in the presence of barbaloin and little inhibited barbaloin transformation. Nojirimycin bisulfite, a specific inhibitor of glucosidases, potently inhibited the growth with barbaloin, but did not affect the growth with glucose or cellobiose. Also, nojirimycin bisulfite completely inhibited the transformation of barbaloin to aloe-emodin anthrone. These results indicate that a unique enzyme capable of cleaving the C-glycosyl bond is induced in strain BAR by barbaloin and, consequently, strain BAR grows by utilizing as a nutrient the carbohydrate liberated from barbaloin. It is further suggested that the barbaloin-cleaving enzyme is inhibited by nojirimycin bisulfite and that the induction of the enzyme is repressed with D-glucose and D-galactose.     

Induction and inhibition of novel sulfotransferase in a human intestinal bacterium, Eubacterium sp. A-44

Induction and inhibition of a novel sulfotransferase produced by Eubacterium sp. A-44 isolated from human feces have been studied. Production of the enzyme was induced by phenylsulfate esters, sulfate donor substrates, but not by phenols, sulfate acceptor substrates, or inorganic sulfate. p-Nitrophenylsulfate (PNS), a good donor substrate, stimulated enzyme production more than 10-fold. Sulfotransferase production was strongly inhibited by phenylphosphate esters. Enzyme activity was competitively inhibited by phenylphosphate esters, but not by inorganic phosphate. High yields of sulfotransferase from sonicated cells were obtained when the bacteria were grown in a media containing 0.6% (w/v) or less of glycine.     

The heterocyclic ring fission and dehydroxylation of catechins and related compounds by Eubacterium sp. strain SDG-2, a human intestinal bacterium.

A human intestinal bacterium, Eubacterium (E.) sp. strain SDG-2, was tested for its ability to metabolize various (3R)- and (3S)-flavan-3-ols and their 3-O-gallates. This bacterium cleaved the C-ring of (3R)- and (3S)-flavan-3-ols to give 1,3-diphenylpropan-2-ol derivatives, but not their 3-O-gallates. Furthermore, E. sp. strain SDG-2 had the ability of p-dehydroxylation in the B-ring of (3R)-flavan-3-ols, such as (-)-catechin, (-)-epicatechin, (-)-gallocatechin and (-)-epigallocatechin, but not of (3S)-flavan-3-ols, such as (+)-catechin and (+)-epicatechin.     

Bacillamide, a novel algicide from the marine bacterium, Bacillus sp. SY-1, against the harmful dinoflagellate, Cochlodinium polykrikoides

Bacillamide (1) was isolated as a new algicide against the harmful dinoflagellate, Cochlodinium polykrikoides, from the marine bacterium, Bacillus sp. SY-1, and its structure was elucidated by extensive two-dimensional NMR techniques including ¹H-¹⁵N HMBC analysis and mass analysis. Bacillamide showed algicidal activity against C. polykrikoides with LC₅₀ of 3.2 μg/ml.     

Petrobactin, a photoreactive siderophore produced by the oil-degrading marine bacterium Marinobacter hydrocarbonoclasticus.

Petrobactin is a bis-catecholate, alpha-hydroxy acid siderophore produced by the oil-degrading marine bacterium Marinobacter hydrocarbonoclasticus. The Fe(III)-complexed form of petrobactin is photoreactive in natural sunlight, mediated by the Fe(III)-citrate moiety. The reaction results in decarboxylation of the petrobactin ligand and reduction of Fe(III) to Fe(II). This report is one of the first to show the photoreactivity of Fe(III)-siderophores mediated by the ferric ion-alpha-hydroxy acid group. The demonstration of light-mediated decarboxylation of an Fe(III)-siderophore complex raises questions about a possible functional role for photoreactivity in siderophore-mediated iron uptake.     

Mass spectrometry characterization of endophytic bacterium Curtobacterium sp. strain ER1/6 isolated from Citrus sinensis

The bacteria of the genus Curtobacterium are usually seen as plant pathogen, but some species have been identified as endophytes of different crops and could as such present a potential for disease control and plant growth promotion. We have therefore applied the desorption electrospray ionization mass spectrometry imaging (DESI‐MSI) in the direct analysis of living Curtobacterium sp. strain ER1/6 colonies to map the surface metabolites, and electrospray ionization tandem mass spectrometry (ESI‐MS/MS) for characterization of these compounds. Several colony‐associated metabolites were detected. The ESI‐MS/MS showed characteristic fragmentations for phospholipids including the classes of glycerophosphocholine, glycerophosphoglycerol, and glycerophosphoinositol as well as several fatty acids. Although a secure identification was not obtained, many other metabolites were also detected for this bacteria species. Principal component analysis showed that fatty acids were discriminatory for Curtobacterium sp. ER1/6 during inoculation on periwinkle wilt (PW) medium, whereas phospholipids characterize the bacterium when grown on the tryptic soy agar (TSA) medium.     

Stimulatory effect of red light on starch accumulation in a marine green alga,chlamydomonas sp. strain MGA161

A marine green alga,Chlamydomonas sp. strain MGA161 was cultivated under illumination of red and white lights. The growth rate under red light illumination was almost the same as that in the basic conditions under white light illumination, but red light-grown cells accumulated almost twice as much starch as white light-grown cells. Although there was a slight decrease in carbonic anhydrase activity, red light-illuminated cells had almost 2.3 times the fructose-l,6-diphos-phatase activity of white light-illuminated cells. Red light might stimulate starch accumulation by increasing the amounts of enzymes related to carbon fixation through the phytochrome system. Cells grown under red light degraded 1.6 times as much starch and produced 1.7 times as much hydrogen and 1.6 times as much ethanol compared with cells grown under white light during 12 h of dark anaerobic fermentation.     

Desulfurization of dibenzothiophene, benzothiophene, and other thiophene analogs by a newly isolated bacterium, Gordonia alkanivorans strain 1B

A novel bacterium, Gordonia alkanivorans strain 1B, was isolated from hydrocarbon-contaminated soil. Assessment of the biodegradation of distinct organic sulfur-compounds, such as dibenzothiophene (DBT), benzothiophene (BT), DBT sulfone, and alkylated tiophenic compounds, as the sole source of sulfure was investigated. G. alkanivorans strain 1B was able to remove selectively the sulfur from DBT while keeping intact the remaining carbon-carbon structure. Orthophenyl phenol (2-hydroxybiphenyl) was the only detected metabolic product. The bacterial desulfurization activity was repressed by sulfate. G. alkanivorans straini 1B consumed 310 μM DBT after 120 h of cultivation, corresponding to a specific desulfurization rate of 1.03 μmol/(g of dry cells·h). When an equimolar mixture of DBT/BT was used as a source of sulfur in the growth medium, G. alkanivorans strain 1B assimilated both compounds in a sequential manner, with BT as the preferred source of sulfur. Only when BT concentration was decreased to a very low level was DBT utilized as the source of sulfur for bacterial growth. Thespecific desulfurization overall rates of BT and DBT obtained were 0.954 and 0.813 μmol/(g of dry cells·h), respectively. The newly isolated G. alkanivorans strain 1B has good potential for application in the biodesulfurization of fossil fuels.     

Novel bromotyrosine derivatives that inhibit growth of the fish pathogenic bacterium Aeromonas hydrophila, from a marine sponge Hexadella sp

Three new bromotyrosine derivatives, 11-N-methylmoloka'iamine (1), 11-N-cyano-11-N-methylmoloka'iamine (2), and kuchinoenamine (3), were isolated as antibacterial constituents from a marine sponge Hexadella sp. Their structures were elucidated on the basis of spectral and chemical methods. They exhibited moderate antibacterial activity against the fish pathogenic bacterium Aeromonas hydrophila.     

Rapid dissolution of plutonium in soil by fusion with ammonium hydrogen sulfate followed by plutonium determination by ion exchange and alpha spectrometry

A method was developed for the rapid dissolution of plutonium in soil by fusion with ammonium hydrogen sulfate, and the determination of plutonium content by ion exchange separation and alpha spectrometry. By this method, plutonium in environmental soil containing plutonium oxide in a soluble and/or insoluble form could successfully be determined.     

Presence of exclusively bacteriochlorophyll-c containing substrain in the culture of green sulfur photosynthetic bacterium Chlorobium vibrioforme strain NCIB 8327 producing bacteriochlorophyll-d.

The light-dependent composition change of light harvesting bacteriochlorophyll(BChl)s in the present culture of a green sulfur photosynthetic bacterium Chlorobium (Chl.) vibrioforme f. sp. thiosulfatophilum strain NCIB 8327 was investigated by visible absorption spectroscopy and HPLC analyses. When the culture was repeatedly grown in liquid media under a low light condition, both the Soret and Qy absorption bands of the in vivo spectrum were shifted to longer wavelengths. Analysis of the extracted pigments by HPLC revealed that the ratio of the amount of BChl-c to that of BChl-d molecules gradually increased during repeated cultivation. In contrast, when the culture grown under a low light intensity was transferred to a high light condition and continued to be grown, the absorption bands were shifted to shorter wavelengths and the ratio of BChls-c/d decreased finally to the almost original value. Colonies were prepared on solid agar media from the liquid culture containing both BChls-c and d, which was grown under a low light intensity. Each colony obtained was found to contain either BChl-c or d, but not both of them. Two types of cells isolated in this study were derived from the same clone, judged from their genetic analyses. The variation of pigment composition in our liquid culture observed here could be ascribed to the difference of growth rates between two substrains containing BChl-c and BChl-d, respectively, depending on light conditions.     

Stereostructure of komodoquinone A, a neuritogenic anthracycline, from marine Streptomyces sp. KS3

The absolute stereostructure of komodoquinone A (1), a neuritogenic anthracycline, which was isolated from a cultured marine Streptomyces sp. KS3, has been determined on the basis of chemical derivatization. Komodoquinone A (1) induces neuronal cell differentiation in the neuroblastoma cell line, Neuro 2A and arrests the cell cycle at the G1 phase. The effect of a solid-state medium on the production of 1 and its aglycone, komodoquinone B (2), was examined.     

Global characterization of the photosynthetic glycerolipids from a marine diatom Stephanodiscus sp. by ultra performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight mass spectrometry

The photosynthetic glycerolipids composition of algae is crucial for structural and physiological aspects. In this work, a comprehensive characterization of the photosynthetic glycerolipids of the diatom Stephanodiscus sp. was carried out by ultra performance liquid chromatography-electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC-ESI-Q-TOF MS). By use of the MS^E data collection mode, the Q-TOF instrument offered a very viable alternative to triple quadrupoles for precursor ion scanning of photosynthetic glycerolipids and had the advantage of high efficiency, selectivity, sensitivity and mass accuracy. Characteristic fragment ions were utilized to identify the structures and acyl compositions of photosynthetic glycerolipids. Comparing the abundance of fragment ions, it was possible to determine the position of the sn-glycerol-bound fatty acyl chains. As a result, four classes of photosynthetic glycerolipid in the extract of Stephanodiscus sp. were unambiguously identified, including 16 monogalactosyldiacylglycerols (MGDGs), 9 digalactosyldiacylglycerols (DGDGs), 23 sulfoquinovosyldiacylglycerols (SQDGs) and 8 phosphatidylglycerols (PGs). As far as our knowledge, this is the first report on global identification of photosynthetic glycerolipids, including lipid classes, fatty acyl composition within lipids and the location of fatty acids in lipids (sn-1 vs. sn-2), in the extract of marine microalgae by UPLC-ESI-Q-TOF MS directly.     

Padanamides A and B, highly modified linear tetrapeptides produced in culture by a Streptomyces sp. isolated from a marine sediment

Two highly modified linear tetrapeptides, padanamides A (1) and B (2), are produced by laboratory cultures of a Streptomyces sp. obtained from a marine sediment. Padanamide B is cytotoxic to Jurkat cells, and a chemical genomics analysis using Saccharomyces cerevisiae deletion mutants suggested that padanamide A inhibits cysteine and methionine biosynthesis or that these amino acids are involved in the yeast's response to the peptide.