Factors influencing odour production by actinomycetes

Odour production by actinomycete (Streptomyces spp.) strains isolated from hypereutrophic natural waters in which muddy odours in fish have occurred, were studied by the ISP (International Streptomyces Project) carbon utilization method. The streptomycete strains were isolated from water, bottom mud and aquatic plants. Nine different carbon sources were used. Odour character was determined by sniffing the cultures. Odour production varied depending on the strain and the carbon source used. Some of the strains produced similar odours in all media regardless of the carbon source. In other strains, the odour varied depending on the carbohydrate used. The total colony counts of actinomycetes may not necessarily indicate the role of actinomycetes in odour problems in the aquatic environment because the odour production by actinomycetes depends on environmental factors.     

The effect of air ions on liquid evaporation rates

The evaporation rates of water, heptane, ethyl alcohol and physiological saline were investigated as a function of atmospheric ion density.Ion concentrations up to about 10⁶ ions/cm³ were employed. In general evaporation rates decreased with increasing ion density (of either sign)to a minimum after which evaporation increased steadily. For water a reduction of about 15% occurred.The different liquids exhibited some deviations from this general pattern. The effects are specific to the type of gas ion, being exceptionally great for ionized oxygen. They also seem to be associated with the polar nature of the liquid molecules. The results are qualitatively explained on the basis of surface charging.The modification of evaporation may be a mechanism by which biological effects are produced by air ions.

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Zusammenfassung Die Verdunstungsquoten von Wasser,Heptan,Äthylalkohol und physiologischer Kochsalzlösung wurden als Funktion der atmosphärischen Ionenkonzentration untersucht. Es wurden Ionenkonzentrationen oberhalb von etwa 10⁶ Ionen/cm³ benutzt. Im allgemeinen nahmen die Verdunstungsquoten mit steigender Ionenkonzentration (jeden Vorzeichens) bis zu einem Minimum ab,nach dem die Verdunstung wieder allmählich anstieg. Für Wasser ergab sich eine Abnahme um etwa 15%. Die verschiedenen Flüssigkeiten zeigten einige Abweichungen von diesem allgemeinen Trend. Die Wirkungen sind für Gasionen spezifisch und besonders gross für ionisierten Sauerstoff.Sie scheinen auch mit dem Vorzeichen der flüssigen Moleküle gekoppelt zu sein.Die Ergebnisse werden qualitativ mit der Oberflächenladung erklärt. Die Änderung der Verdunstung ist möglicherweise ein Mechanismus, durch den biologische Wirkungen durch Luftionen hervorgerufen werden.

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Resume On a étudié le taux d'évaporation de l'eau, de l'heptane, de l'alcool éthylique et du sérum physiologique (solution acqueuse de sel de cuisine)en fonction de la densité des ions dans l'atmosphère. Pour ce faire, on a utilisé des concentrations en ions allant jusqu'à 10⁶ ions/cm³. En général, le taux d'évaporation diminue parallèlement à l'augmentation de la densité des ions (quel que soit leur signe) et cela jusqu'à un minimum au-delà duquel il augmente de nouveau. Pour l'eau,la réduction est d'environ 15%. Les différents liquides examinés présentent quelques variantes de cette tendance générale. L'effet constaté est spécifique pour les ions gazeux et spécialement important pour l'oxygène ionisé. Il paraît aussi lié à la polarité de la molécule liquide. Les résultats obtenus sont qualitativement explicables en tenant compte de la charge superficielle du liquide. La variation de l'évaporation est peut-être le mécanisme par le truchement duquel les ions de l'air exercent une influence biologique.

     

Factors influencing uranium reduction and solubility in evaporation pond sediments

Evaporation ponds in the San Joaquin Valley (SJV), CA, USA that are used for the disposal of irrigation drainage waters, contain elevated levels of U that may be a threat to pond wildlife. The ponds support euryhaline algae, which become incorporated in the sediments as depositional organic matter (OM) – facilitating reducing conditions. Our earlier studies have shown that U in one SJV sediment was primarily present as the highly soluble U(VI) species (as opposed to the less soluble U(IV) species), despite the presence of volatile sulfides. In this research, we investigated the effects of native pond algae (Chlorella) and potential reducing agents on U redox chemistry of SJV pond sediments. San Joaquin Valley pond sediments were equilibrated with natural and synthetic pond inlet waters containing approximately 10 mg U(VI) L-1 to which reducing agents (acetate, sucrose, and alfalfa shoot) were added. The equilibrations were done under oxic (Chlorella only) and O2-limiting conditions (remaining treatments). Sediments were examined for changes in average U oxidation state by X-ray near- edge absorption structure (XANES) spectroscopy and U concentration by ICP-MS.For the alfalfa treatments, a 95 percent loss of U(VI) from solution, the presence of sulfides, and results from the XANES studies suggest U(VI) was reduced to U(IV). Upon exposure to air, the precipitated U was readily oxidized, suggesting the reduced U is susceptible to oxidation. Much less reduction of U(VI) was observed in the other 3 treatments and the solid phase was dominated by U(VI) as in the natural pond sediments. A second study was conducted with pond sediment-water suspensions to determine the effects of controlled PCO2 and low redox potential (Eh) on U solubility. These suspensions were equilibrated at 0.22 and 5.26 kPa PCO2 and allowed to free-drift from an oxidized to a reduced state. At high Eh and high PCO2, dissolved U concentrations were higher than in the low PCO2 systems due to greater complexation with CO3. Dissolved U concentrations decreased only under intense sulfate reducing conditions, even at low Eh conditions. It appears that U reduction occurred by chemical reduction via sulfide ion. Comparing the XANES data of the pond sediments with the laboratory-produced solids we conclude that biosorption by algae and bacteria is the dominant mechanism depositing U in the sediments. Even though there are organisms that can use U(VI) as a terminal electron acceptor, we found that sulfate reduction was preferred in these high- SO4 waters. Mixed oxidation state U-solids were preferentially formed in the pond sediments and in the lab except under intense SO4 reducing conditions.     

Biodegradation of organic pollutants by halophilic bacteria and archaea

Hypersaline environments are important for both surface extension and ecological significance. As all other ecosystems, they are impacted by pollution. However, little information is available on the biodegradation of organic pollutants by halophilic microorganisms in such environments. In addition, it is estimated that 5% of industrial effluents are saline and hypersaline. Conventional nonextremophilic microorganisms are unable to efficiently perform the removal of organic pollutants at high salt concentrations. Halophilic microorganisms are metabolically different and are adapted to extreme salinity; these microorganisms are good candidates for the bioremediation of hypersaline environments and treatment of saline effluents. This literature survey indicates that both the moderately halophilic bacteria and the extremely halophilic archaea have a broader catabolic versatility and capability than previously thought. A diversity of contaminating compounds is susceptible to be degraded by halotolerant and halophile bacteria. Nevertheless, significant research efforts are still necessary in order to estimate the true potential of these microorganisms to be applied in environmental processes and in the remediation of contaminated hypersaline ecosystems. This effort should be also focused on basic research to understand the overall degradation mechanism, to identify the enzymes involved in the degradation process and the metabolism regulation.     

Biomineralization of carbonate and phosphate by moderately halophilic bacteria

We investigated the precipitation of carbonate and phosphate minerals by 19 species of moderately halophilic bacteria using media with variable Mg(2+)/Ca(2+) ratios. The precipitated minerals were calcite, magnesium (Mg) calcite, and struvite (MgNH(4)PO(4) x 6H(2)O) in variable proportions depending on the Mg(2+)/Ca(2+) ratio of the medium. The Mg content of the Mg-calcite decreased with increasing Ca(2+) concentration in the medium. According to the saturation indices, other minerals could also have precipitated. We observed important differences between the morphology of carbonate and phosphate, which may help us to recognize these minerals in natural systems. We studied the growth and pH curves of four bacteria in media specific for carbonate and struvite precipitation. We consider the biomineralization processes that produce carbonate and phosphate minerals, and propose a hypothesis for the lack of struvite in natural environments and ancient rocks.     

Factors influencing production of 5(E)-19-nor-10-keto-vitamin D3 by rumen bacteria

Mixed populations of rumen bacteria or Clostridium hastiforme (a rumen isolate) catalyzed the oxidation of vitamin D3 to 5(E)-19-nor-10-keto-vitamin D3. The reaction depended upon small amounts of O2 (less than 0.1% dissolved O2); when O2 was available, supernatant obtained from heat-killed mixed cultures also produced 5(E)-19-nor-10-keto-vitamin D3. Results obtained by ultrafiltration indicated that at least two heat-stable factors of bacterial origin were involved. Lower rates of the same oxidation were observed when O2 was introduced to solutions containing vitamins D3 and L-cysteine. Oxygen radicals are known to be produced in such solutions and the involvement of such radicals in the D3 oxidation is probable since production in cysteine solutions was inhibited by superoxide dismutase and catalase.     

嗜盐细菌中四氢嘧啶和羟基四氢嘧啶的生物合成及其生物学功能

在嗜盐细菌盐适应中,四氢嘧啶(1,4,5,6-四氢-2-甲基-4-嘧啶羧酸)和羟基四氢嘧啶(1,4,5,6-四氢-2-甲基-5-羟基-4-嘧啶羧酸)发挥着十分重要的作用.四氢嘧啶的生物合成以L-天冬氨酸-β-半醛(ASA)为底物,依次由2,4.二氨基丁酸转氨酶(EctB),2,4--氨基丁酸乙酰基转移酶(EctA)和四...     

Effect of temperature on the growth rates of halotolerant and halophilic bacteria isolated from Antarctic saline lakes

Summary The effect of temperature on the growth rates of Halomonas subglaciescola and a Halobacterium sp., halotolerant and halophilic bacteria isolated from Antarctic saline lakes, was predicted accurately by models which propose a linear relationship between temperature and the square root of the reciprocal of the growth rate. The cardinal temperatures of the strains examined were in general 5–10°C lower than those of taxonomic counterparts isolated from temperate and tropical environments. Temperature dependence data for strains of the Halobacterium sp. and annual temperature profiles of Deep Lake allowed estimation of the in situ potential for growth.     

Factors affecting ethylene production by some plant pathogenic bacteria

Summary Methionine, up to 10^–3 M, added to a basal medium enhanced bacterial ethylene production in 14 of the 20 bacteria tested. The effects of substrate, cofactors, light, and temperature on ethylene production byPseudomonas solanacearum #25 revealed that the greatest effect occurred when 10^–5 M methionine and 10^–4 M FMN were combined, from which 4.10l/l of ethylene were produced. Higher levels of methionine resulted in production of high levels of non-enzymically produced ethylene and death of the bacteria. This non-enzymic production of ethylene was eliminated in the dark. Copper had no effect upon ethylene production. Twenty-nine and 35°C were inhibitory, whereas 19°C appeared to be near optimum for ethylene production.Pseudomonas solanacaerum #25 and some other bacteria are capable of ethylene production and methionine and FMN enhance this production.This work was supported by the Fred C. Gloeckner Foundation and the University of Minnesota Graduate School Grant in Aid #496-0307-4909-02.     

Methanethiol utilization and sulfur reduction by anaerobic halophilic saccharolytic bacteria

A number of sulfur compounds were tested as sulfur sources for the growth of three strains of anaerobic halophilic saccharolytic bacteria isolated from hypersaline water bodies of the eastern Crimea (USSR). Dithionite and sulfite at 1 mM concentration completely inhibited the growth of all strains. Methanethiol turned out to be the sole sulfur source for growth ofHalobacteroides strains in the defined medium with glucose and leucine. Methanethiol also stimulated growth of cultures in the complex medium with yeast extract. TheHaloincola saccharolytica Z-7787 appeared to be capable of methanethiol formation from methionine. All organisms studied were capable of heterotrophic sulfur reduction, producing up to 13 mM H₂S, but no evidence that they gain energy from the process has been obtained. The extremely halophilicHalobacteroides lacumaris may participate in sulfidogenesis at the high salinity (20–30% NaCl). The ecological position of haloanaerobes in halophilic community is discussed.     

Factors influencing the production of cellulases by Sporotrichum thermophile.

Cellulase production and growth of a strain of Sporotrichum thermophile were studied by using a mineral salts medium supplemented with yeast extract and insoluble cellulose. The effects of cultural conditions, such as pH, nitrogen source, substrate concentration, and temperature, were examined. Maximum production of C1 and CX cellulases occurred at 45 C in 2 to 4 days, in the presence of 1% Solka/Floc as substrate, when NaNO3 or urea used as sources of nitrogen. Under these conditions, cellulolytic activity of culture filtrates appeared to be similar to that reported for Trichoderma viride grown in a favorable environment. However, comparable yields of cellulase were produced by S. thermophile in less than one-quarter the time required by mesophilic fungi.     

Factors influencing the production of cellulases by Sporotrichum thermophile.

Cellulase production and growth of a strain of Sporotrichum thermophile were studied by using a mineral salts medium supplemented with yeast extract and insoluble cellulose. The effects of cultural conditions, such as pH, nitrogen source, substrate concentration, and temperature, were examined. Maximum production of C1 and CX cellulases occurred at 45 C in 2 to 4 days, in the presence of 1% Solka/Floc as substrate, when NaNO3 or urea used as sources of nitrogen. Under these conditions, cellulolytic activity of culture filtrates appeared to be similar to that reported for Trichoderma viride grown in a favorable environment. However, comparable yields of cellulase were produced by S. thermophile in less than one-quarter the time required by mesophilic fungi.     

Factors influencing biohydrogenation and conjugated linoleic acid production by mixed rumen fungi

The objective of this study was to evaluate the effect of soluble carbohydrates (glucose, cellobiose), pH (6.0, 6.5, 7.0), and rumen microbial growth factors (VFA, vitamins) on biohydrogenation of linoleic acid (LA) by mixed rumen fungi. Addition of glucose or cellobiose to culture media slowed the rate of biohydrogenation;only 35-40% of LA was converted to conjugated linoleic acid (CLA) or vaccenic acid (VA) within 24 h of incubation, whereas in the control treatment, 100% of LA was converted within 24 h. Addition of VFA or vitamins did not affect biohydrogenation activity or CLA production. Culturing rumen fungi at pH 6.0 slowed biohydrogenation compared with pH 6.5 or 7.0. CLA production was reduced by pH 6.0 compared with control (pH 6.5), but was higher with pH 7.0. Biohydrogenation of LA to VA was complete within 72 h at pH 6.0, 24 h at pH 6.5, and 48 h at pH 7.0. It is concluded that optimum conditions for biohydrogenation of LA and for CLA production by rumen fungi were provided without addition of soluble carbohydrates, VFA or vitamins to the culture medium; optimum pH was 6.5 for biohydrogenation and 7.0 for CLA production.