Cysteine and S-sulfocysteine biosynthesis in phototrophic bacteria

Forteen species (17 strains) of phototrophic bacteria as well as one strain of Thiobacillus denitrificans were tested for cysteine synthase and S-sulfocysteine synthase. All strains contain cysteine synthase active with O-acetylserine; only the Chromatiaceae, two species of the Rhodospirillaceae and T. denitrificans contain S-sulfocysteine synthase. In six species repression by different sulfur compounds in the medium was studied. In Chromatium vinosum, cysteine synthase was found to be constitutive, while in the Rhodospirillaceae tested the enzyme is repressed by sulfide. Thiosulfate had a derepressive effect in Rhodopseudomonas globiformis but strongly repressed cysteine synthase in R. sulfidophila and R. palustris. Cysteine had only moderate effects with the species tested.     

Growth yields of green sulfur bacteria in mixed cultures with sulfur and sulfate reducing bacteria

1. Dry weight yields from mixed cultures ofProsthecochloris aestuarii orChlorobium limicola with the sulfur reducingDesulfuromonas acetoxidans were determined on different growth limiting amounts of acetate, ethanol or propanol. The obtained yields agreed well with values predicted from stoichiometric calculations. 2. From mixed cultures of twoChlorobium limicola strains withDesulfovibrio desulfuricans orD. gigas on ethanol as the growth limiting substrate, dry weight yields were obtained as calculated for the complete utilization of the ethanol by the mixed cultures. 3. Dry weight yield determinations for two pure cultures ofChlorobium limicola with different growth limiting amounts of sulfide in the absence and presence of excess acetate confirmed that acetate is incorporated byChlorobium in a fixed proportion to sulfide; compared to the yield in the absence of acetate the yield is increased two to threefold in the presence of acetate. 4. The lowest possible sulfide concentrations necessary for optimal growth of mixed cultures of eitherProsthecochloris orChlorobium withDesulfuromonas on acetate were 7–8 mg H₂S per liter of medium. 5. Doubling times at the growth rate limiting light intensities of 5, 10, 20, 50, 100 and 200 lux were determined under optimal growth conditions for the following phototrophic bacteria:Prosthecochloris aestuarii, Chlorobium phaeovibriodes, Chromatium vinosum andRhodopseudomonas capsulata. Reasonably good growth was still obtained withProsthecochloris at 10 and 5 lux light intensity at which no growth of the purple bacteria could be observed.     

Microbial mats in tidal channels at San Carlos,Baja California Sur,Mexico

Microbial communities of stratified phototrophic bacteria in laminated intertidal sediments north of Estuary El Puente, near San Carlos, Baja California Sur, Mexico,‐were studied. This study describes the macroscopic and microscopic characteristics of the mats, including their annual growth. The mats were located in and along meandering mangrove‐lined tidal channels. Their thickness ranged from 0.5 to 25 cm. Square‐meter areas of polygonal mats were detected in several ponds infiltrated by sea water. The principal microbial community of the upper surface of various morphotypes of microbial mats was identified as cyanobacteria belonging to the genera Microcoleus, Lyngbya, Phormidium, and Oscillatoria. Other cyanobacte‐rial genera such as Pseudanabaena, Spirulina, Synechococcus, and Gloeocapsa, as well as many unidentified diatoms, were also present but at lower population densities. The second inward reddish layers of the microbial mats contained similar cyano‐bacterial genera plus anoxygenic phototrophic bacteria belonging to the genera Chloroflexus, Thiocapsa, Chromatium, Prosthecochloris, Rhodopseudomonas, and Chlorobium, as well as several unidentified bacteria. In situ measurements on the growth of the mats, from intermittent tide sites, showed an annual buildup of two layers: green and reddish. These layers corresponded to a vertical growth of 1.4 ± 0.27 mm/year. Permanently submerged mats did not show vertical growth during the same period of time.     

Viable phototrophic sulfur bacteria from the Black-Sea bottom

Phototrophic sulfur bacteria were isolated from Black-Sea mud at depths of 660 and 2,240 m. The species obtained in pure cultures were identified asChromatium warmingii andThiocapsa roseopersicina. In addition,Chlorobium phaeovibrioides occurred in enrichment cultures. The findings prove that Chromatiaceae and Chlorobiaceae are capable of survival in 2000 m depth, in the dark, in the presence of H₂S and organic materials. There is, however, no evidence for growth or reproduction of these organisms in this environment.     

A modified method for the cultivation of phototrophic bacteria

Simplified anaerobic media and a convenient method for the cultivation of Rhodospirillaceae, Chlorobiaceae, Chloroflexaceae and Chromatiaceae are described. The modified conditions assure almost complete anaerobiosis for media, growth and maintenance.Strains representing several species of Rhodospirillaceae, Chlorobiaceae and Chromatiaceae were successfully grown within relatively short times with full pigmentation, indicating that the new media and cultivation conditions were most suited for photoautotrophic growth.     

Is intracytoplasmic membrane structure a generic criterion? It does not coincide with phylogenetic interrelationships among phototrophic purple nonsulfur bacteria

The 16S rRNA or rRNA gene sequences of the type strains of 5 species of Rhodobacter, Rhodopseudomonas blastica and Paracoccus denitrificans were determined. The sequence analysis revealed that Rhodobacter species, whose intracytoplasmic membrane systems were characteristically vesicular, composed a sole cluster. Rhodopseudomonas blastica, whose intracytoplasmic membrane system was lamellar, was included in the cluster of Rhodobacter. The phylogenetic co-clustering of these bacteria conformed to their possessing of the identical types of carotenoids. Paracoccus denitrificans, which is nonphototrophic, is a right member of the Rhodobacter cluster. Rhodobacter species, Rhodopseudomonas blastica and Paracoccus denitrificans are apart from the other phototrophic bacteria and have the common deletions of 21 bases at the positions 1258 to 1278 (Escherichia coli numbering system). It was demonstrated that the morphological character intracyto-plasmic membrane structure, that has been regarded as a generic criterion does not reflect the phylogeny in the phototrophic bacteria. The transfer of Rhodopseudomonas blastica to the genus Rhodobacter is proposed.     

Anti-protease and Immunomodulatory Activities of Bacteria Associated with Caribbean Sponges

Marine sponges and their associated bacteria have been proven to be a rich source of novel secondary metabolites with therapeutic usefulness in cancer, infection, and autoimmunity. In this study, 79 strains belonging to 20 genera of the order Actinomycetales and seven strains belonging to two genera of the order Sphingomonadales were cultivated from 18 different Caribbean sponges and identified by 16S rRNA gene sequencing. Seven of these strains are likely to represent novel species. Crude extracts from selected strains were found to exhibit protease inhibition against cathepsins B and L, rhodesain, and falcipain-2 as well as immunomodulatory activities such as induction of cytokine release by human peripheral blood mononuclear cells. These results highlight the significance of marine sponge-associated bacteria to produce bioactive secondary metabolites with therapeutic potential in the treatment of infectious diseases and disorders of the immune system.     

Chitinolytic bacteria of the mammal digestive tract

Chitinolytic bacteria were isolated from the digestive tract of different mammals and characterized. All isolates were facultatively anaerobic, long Gram-positive, straight rods resemblingClostridium sp. Only one isolate consisted of Gram-positive ovoid cells. All cultures grew on glucose,N-acetylglucosamine, glucosamine, galactose, starch, hemicellulose and xylan. Fermentation products were mainly formate, acetate, butyrate and lactate. The isolates were identified asClostridium sartagoforme (2 species),C. aminovalericum, C. bifermentans andEnterococcus durans (1 isolate of each species). Exocellular fractions of all strains exhibited higher activities of all enzymes than cellular ones. Inductive effects of hemicelluloses, pectin and laminarine on chitinases were demonstrated. High exocellular endochitinase activity was found in cultures grown on chitin.N-Acetylglucosaminidase activity was low with the exception of exocellular fractions of two strains ofC. sartagoforme.     

Phototrophic purple and green bacteria in a sewage treatment plant

In all purification stages of a biological sewage treatment plant, phototrophic bacteria were detected by the method of viable cell counts. The predominant species identified belonged to the genus Rhodopseudomonas of purple nonsulfur bacteria. The number of phototrophic bacteria was highest in wastewater containing sludge. In activated sludge, an average of 10(5) viable cells/ml was found; the number depended upon concentration of sludge rather than on seasonal changes in light conditions in the course of a year. Bacteriochlorophyll a was extracted from activated sludge. Relative to the viable counts of phototrophic bacteria, the content of bacteriochlorophyll a was 5- to 10-fold higher than that of three representative pure cultures. By incubation of activated and digester sludge under different environmental conditions, it was shown that phototrophic bacteria can complete with other bacteria only under anaerobic conditions in the light.     

A new method for liquid nitrogen storage of phototrophic bacteria under anaerobic conditions

A simple, effective and economical method for the long-term preservation of bacteria in liquid nitrogen under anaerobic conditions is described. As a case example anaerobic photosynthetic bacteria were successfully preserved. Gas tight small screw-cap glass ampoules with butyl rubber septa were used for freezing the specimen anaerobically. During experimental manipulations no anaerobic chamber or glove boxes were required. All teste cultures yielded high recoveries after repeated thawing and during storage. After freezing, survival recoveries of Rhodospirillaceae range from 70–100%, whereas with strict anaerobic strains of Chlorobiaceae and Chromatiaceae a maximum loss of 1–2 log₁₀ counts was observed. No further loss in viability occurred after 1–2 years of storage.The small size of the ampoules and the use of single ampoule for 15–20 repeated retrievals proved economical with respect to storage space and costs.The system is compact and suitable for the preservation of anaerobic phototropic bacteria and other fragile anaerobic microorganisms.     

Phototrophic purple and green bacteria in a sewage treatment plant.

In all purification stages of a biological sewage treatment plant, phototrophic bacteria were detected by the method of viable cell counts. The predominant species identified belonged to the genus Rhodopseudomonas of purple nonsulfur bacteria. The number of phototrophic bacteria was highest in wastewater containing sludge. In activated sludge, an average of 10(5) viable cells/ml was found; the number depended upon concentration of sludge rather than on seasonal changes in light conditions in the course of a year. Bacteriochlorophyll a was extracted from activated sludge. Relative to the viable counts of phototrophic bacteria, the content of bacteriochlorophyll a was 5- to 10-fold higher than that of three representative pure cultures. By incubation of activated and digester sludge under different environmental conditions, it was shown that phototrophic bacteria can complete with other bacteria only under anaerobic conditions in the light.     

Diversity and antibacterial activity of bacteria isolated from the coastal marine sponges Amphilectus fucorum and Eurypon major

Aims: To assess the diversity and antimicrobial activity of culturable bacteria associated with two temperate‐water marine sponges, Amphilectus fucorum and Eurypon major. Methods and Results: Sponge samples were collected in August 2008 and bacteria were cultured on several different media. The 16S rRNA gene of representative strains was sequenced to allow classification. It was found that Proteobacteria were the dominant group of bacteria cultured from both sponges, but overall, the bacterial composition was diverse and distinct between the sponges. The most notable features were the significantly higher proportion of firmicutes in E. major and the low frequency of actinobacteria in both sponges. Four bacterial isolates were identified as potentially novel species and will be characterised in future studies. Approximately 400 cultured bacteria were screened for antimicrobial activity against a collection of indicator strains, with only eight strains, all Pseudovibrio spp., displaying any such activity. These strains were active against Escherichia coli and Bacillus subtilis but not Staphylococcus aureus or a selection of fungal strains. Conclusions: Diverse and distinct populations of culturable bacteria are present in the coastal sponges A. fucorum and E. major. Only a minority of isolates produce antibacterial metabolites in culture, but this activity is common in Pseudovibrio spp. Significance and Impact of the Study: This study illustrates the diversity of sponge‐associated bacteria and the need to increase our knowledge about the function of these symbiotic bacteria. The data suggest that production of antibacterial metabolites is restricted to a subset of species, with the majority involved in other functions. The importance of Pseudovibrio as a reservoir of antibacterial metabolites is also highlighted.     

The isolation ofChromatium Okenii and its behaviour in different media

Summary An enrichment culture ofChromatium Okenii, obtained from mud of a ditch at Delft, was used for isolation of this species. The bacteria of the strain, isolated by making 5 successive shake cultures in an agar medium were, however, less than half the size ofChr. Okenii when cultivated under the same conditions as the bacteria in the original culture.By variation of the culture conditions for the pure strain, it appeared that in a mineral medium containing fairly high concentrations of sodium thiosulphate and fairly low concentrations of sodium malate, bacteria developed of nearly the same size as present in the enrichment culture. This supports the view ofWinogradsky that media of this type offer the most natural conditions to purple sulphur bacteria.It is, therefore, evident thatChr. Okenii is a highly pleomorphic species, and the consequences hereof for the differentiation of species within the genusChromatium were discussed.     

Selective enrichment of green sulfur bacteria in the presence of 4-aminobenzenesulfonate (sulfanilate)

A novel selective enrichment method is described for phototrophic green sulfur bacteria even in the presence of purple sulfur and purple nonsulfur bacteria using sulfanilate, which was discovered during efforts to selectively isolate sulfanilate-metabolizing anoxygenic phototrophic bacteria from marine habitats. Samples for these experiments were obtained from beaches, saltpans, subsurface mangrove soils, fish and prawn aquaculture ponds and backwaters of the East and West coasts of India. Photoorganoheterotrophic and photolithoautotrophic enrichments in the absence of sulfanilate predominantly yielded purple bacterial enrichments. In contrast, photolithoautotrophic enrichments in the presence of sulfanilate yielded green-colored enrichments from the same samples. Whole cell absorption spectra of the enrichment cultures revealed the presence of bacteriochlorophyll c and thus green phototrophic bacteria. Microscopic observation demonstrated the presence of sulfur globules outside the bacterial cells and the presence of non-motile cells, some of which had prosthecae. 16S rDNA sequences obtained from green sulfur bacterial strains isolated from enrichment cultures confirmed the presence of representatives of the green sulfur bacterial genera Prosthecochloris and Chlorobaculum. The selective pressure of sulfanilate exerted through inhibition of phototrophic purple sulfur bacteria was demonstrated by inhibition studies using the purple sulfur bacteria Marichromatium indicum JA100 and Marichromatium sp. JA120 (JCM 13533) and the green sulfur bacterium Prosthecochloris sp. JAGS6 (JCM 13299).     

Breakdown ofd-glucose by mixed cultures ofEscherichia coli,Desulfovibrio vulgaris,andChromatium vinosum

Experiments with mixed cultures ofEscherichia coli, Desulfovibrio vulgaris, andChromatium vinosum were conducted using a synthetic medium with glucose as the substrate. The bacterial number and the changes in the chemical factors were determined during the development of the mixed culture. (i) Fermentation of glucose byE. coli produces organic acids (formic, acetic, lactic, and succinic) and alcohol. The growth-yield constant K (cell dry weight per weight solid substrate) does not exceed 0.05. (ii) In the mixed culture ofE. coli andD. vulgaris, the reduction of sulfate is accompanied by a total consumption of formate, lactate, and alcohol and an increase in the sulfide and acetate content. (iii) When the three physiologically different species are allowed to grow simultaneously, there is no accumulation of catabolites in the medium and the growth yield constant increases to 0.46. Maximum phototrophic production requires the presence of bothE. coli andD. vulgaris. A low substrate concentration and the simultaneous growth of the three organisms are other factors that contribute towards a high output. The biochemical parameters of the medium are influenced to a large extent by the glucose level. The results suggest that the behavior of the strains is different in pure and mixed cultures.     

Fermentation of pyruvate by 7 species of phototrophic purple bacteria]

The dark, anaerobic fermentation of pyruvate under growth conditions was examined with the following species of phototrophic purple bacteria: Rhodospirillum rubrum strains Ha and S1, Rhodopseudomonas gelatinosa strain 2150, Rhodopseudomonas acidophila strain 7050, Rhodopseudomonas palustris strain ATCC 17001, Rhodopseudomonas capsulata strains Kb1 and 6950, Rhodopseudomonas sphaeroides strain ATCC 17023, and Chromatium vinosum strain D. Fermentation balances were established for all experiments. Under fermentative conditions cell protein and dry weight increased only slightly, if at all. The species differed considerably in their fermentative activity; R. rubrum and R. gelatinosa exhibited the highest rates (2-8 mumoles pyruvate/mg protein-h). R. acidophila and R. capsulata showed an intermediate fermentation rate (0.4--2.0 mumoles pyruvate/mg protein-h), while the other strains tested fermented at quite low rates (0.2-0.4 mumoles pyruvate/mg protein-h). The extremes of fermentation times were from 30-380 hours. Based on the products of fermentation which were formed in addition to acetate, formate, and CO2, the species can be grouped as follows: a) R. rubrum, R. gelatinosa, and R. sphaeroides additionally form propionate. b) R. gelatinosa, R. palustris, R. capsulata, R. sphaeroides, and C. vinosum additionally form lactate. R. palustris also produces butyrate. c) R. acidophila and R. capsulata additionally form much 2,3-butanediol, acetoin, and diacetyl. Small amounts of acetoin were formed by the rest of the strains. A comparison of the fermentation of pyruvate by normal and starved cells (4 days in the light without a carbon source) of R. rubrum and R. gelatinosa shows that the latter ferment more slowly and produce less acetate and formate, but more propionate or lactate. The fermentation of pyruvate by R. rubrum was also studied in cultures in which the pH fell (7.2--6.6). Compared with the fermentation at neutral pH (7.3, 7.4), the following differences were found: a slower fermentation rate, an increased production of dry weight, an increased formation of propionate, but a reduced formation of acetate and a very low production of formate.     

Variability in fermentation patterns of sugar-utilizing bacteria isolated from anaerobic,intertidal sediments

Three dominant types of sugar-fermenting bacteria were isolated from the anaerobic, intertidal sediments of the Eems-Dollard estuary by applying techniques involving anaerobic agar shake tubes. One of the isolated types was tentatively identified as aStreptococcus species, the other two asBacteroides species. All types were versatile with respect to the utilization of sugars. The fermentation patterns of two types were dependent upon conditions of cultivation. In glucose-limited cultures ofStreptococcus strain NS.G52, the production of lactate was suppressed in favor of formate, acetate, and ethanol. In glucose-limited syntrophic cultures withMethanospirillum hungatei, Bacteroides strain NS.G42 was forced to produce acetate and hydrogen at the expense of ethanol. The fermentation pattern ofBacteroides strain NS.S42, which consisted of acetate, propionate, and succinate, was not affected by conditions of cultivation.     

Production of elemental sulfur by green and purple sulfur bacteria

The utilization of sulfide by phototrophic sulfur bacteria temporarily results in the accumulation of elemental sulfur. In the green sulfur bacteria (Chlorobiaceae), the sulfur is deposited outside the cells, whereas in the purple sulfur bacteria (Chromatiaceae) sulfur is found intracellularly. Consequently, in the latter case, sulfur is unattainable for other individuals. Attempts were made to analyze the impact of the formation of extracellular elemental sulfur compared to the deposition of intracellular sulfur.According to the theory of the continuous cultivation of microorganisms, the steady-state concentration of the limiting substrate is unaffected by the reservoir concentration (S _R).It was observed in sulfide-limited continuous cultures ofChlorobium limicola f.thiosulfatophilum that higherS _R values not only resulted in higher steady-state population densities, but also in increased steady-state concentrations of elemental sulfur. Similar phenomena were observed in sulfide-limited cultures ofChromatium vinosum.It was concluded that the elemental sulfur produced byChlorobium, althouth being deposited extracellularly, is not easily available for other individuals, and apparently remains (in part) attached to the cells. The ecological significance of the data is discussed.Non-standard abbreviations RP reducing power - BChl bacteriochlorophyll - N_cell cell material - specific growth rate - {ie52-1} maximal specific growth rate - D dilution rate - K _s saturation constant - s concentration of limiting substrate - S _R same ass but in reservoir bottle - Y yield factor - iS^o intracellular elemental sulfur - eS^o extracellular elemental sulfur - PHB poly-beta-hydroxybutyric acid     

Hydroxamate-siderophore production and utilization by marine eubacteria

Siderophore (iron-binding chelator) production was examined in 30 strains of open ocean bacteria from the generaVibrio, Alteromonas, Alcaligenes, Pseudomonas, andPhotobacterium. The results showed that hydroxamate-type siderophore production was widely distributed in various marine species, except for isolates ofAlteromonas macleodii andV. nereis. In all cases, the ability to produce siderophores was under the control of iron levels in the medium and satisfied the iron requirements of the siderophore bioassay organism. On the basis of chemical assay and bacterial bioassays, none of the examined isolates produced phenolate-type siderophores. Several isolates produces siderophores that were neither hydroxamatenor phenolate-type siderophores. Some strains such asAlteromonas communis produce siderophores that could be used by many other isolates. In contrast, the siderophore produced byAlcaligenes venustus had little cross-strain utilization. These findings suggest that the ability to produce siderophores may be common to open ocean bacteria.     

Characterization of marine luminous bacteria isolated off the Coast of China and description ofVibrio orientalis sp. nov.

Luminous strains of marine bacteria, isolated off the Coast of China, were subjected to a phenotypic characterization, which included a test of their ability to utilize 82 organic compounds as sole or principal sources of carbon and energy. A numerical analysis of the data revealed five clusters which were readily identified asPhotobacterium phosphoreum, P. leiognathi, Vibrio harveyi, andV. splendidus biotype I. The remaining cluster of luminous isolates was phenotypically distinct from all the previously described species ofVibrio andPhotobacterium and was given the species designation,Vibrio orientalis. This species differed from all the other luminous species ofVibrio by its ability to accumulate poly-β-hydroxybutyrate as an intracellular reserve product. Additional distinctive properties were the presence of an arginine dihydrolase system, growth at 4° but not 40°C, and the ability to utilize putrescine and spermine.