Factors influencing numbers of Mycobacterium avium, Mycobacterium intracellulare, and other Mycobacteria in drinking water distribution systems

Eight water distribution systems were sampled over an 18-month period (528 water and 55 biofilm samples) to measure the frequency of recovery and number of mycobacteria, particularly Mycobacterium avium and Mycobacterium intracellulare, in raw source waters before and after treatment and within the distribution system. The systems were chosen to assess the influence of source water, treatment, and assimilable organic carbon levels on mycobacterial numbers. Overall, mycobacterial recovery from the systems was low (15% of samples). Numbers of mycobacteria ranged from 10 to 700,000 CFU liter(-1). The number of M. avium in raw waters was correlated with turbidity. Water treatment substantially reduced the number of mycobacteria in raw waters by 2 to 4 log units. Mycobacterial numbers were substantially higher in the distribution system samples (average, 25,000-fold) than in those collected immediately downstream from the treatment facilities, indicating that mycobacteria grow in the distribution system. The increase in mycobacterial numbers was correlated with assimilable organic carbon and biodegradable organic carbon levels (r(2) = 0.65, P = 0.03). Although M. intracellulare was seldom recovered from water samples, it was frequently recovered (six of eight systems) in high numbers from biofilms (average, 600 CFU/cm(2)). Evidently, the ecological niches of M. avium and M. intracellulare are distinct.     

Water repellency of Casuarina windbreaks (Casuarina equisetifolia Forst.) caused by fungi in central Taiwan

The water repellent layer (WRL) in the Casuarina plantation near Taichung Harbor in central Taiwan is mainly due to the development of filamentous fungi. The hyphae of the isolated fungi and the metabolites of the TCHC-5 and TCHC-20 fungi are also significantly hydrophobic. In the soil layers, humic substances decrease the phosphorus fixation and contribute to the formation of WRL. The hydrophobic properties of humic substances are unfavorable for the nutrient cycling in this area. The water contact angles of fulvic acids and humic acids are pH-dependent. Increasing the solution pH value reduces the hydrophobic strength for fulvic acids and/or humic acids. TCHC-15 and TCHC-16 isolated fungi exude strong acidic metabolites (pH 2.7–3.0). This may result in polymerization and/or precipitation of fulvic acids and humic acids and increase the hydrophobic strength of the soil layers. Humic substances with aliphatic chains are the main components that form WRL in soils. Soil pH may be an indicator of the hydrophobic potential for organic matters.     

The Influence of Organic Matter and pH on DDT Aqueous Solubility

We have studied the concentrations of DDT in ground water samples at field locations with DDT-polluted topsoil and concentrations and solubility in samples prepared from deionized water with different types and concentration of organic acids. The solubility of DDT increased with increasing concentration of humic acid when the pH of the samples was low (adjusted to about 5.5). The effect flutters in the humic acid concentration range from 200 to 300?mg/L, in accordance with humic acid hydrophobicity, operationally measured as liquid surface tension. The findings correspond to trends previously reported in the literature. The trend of increasing solubility was not found using fulvic acid or low-molecular-weight aliphatic acids. No trend was found adding humic acid without adjusting the pH. The mechanism of enhanced solubility due to humic compounds can explain relatively high levels of DDT in ground water. The ground water samples, however, had a moderately high concentration of maximum 6?µg/L compared with a maximum of about 2300?µg/L in the water samples with humic acid in pure water.     

Organic biogeochemistry of groundwater at a mountain coal mine

Measurements of dissolved organic matter (DOM), humic and fulvic acids, carbohydrates, tannins + lignins, phenols and amino acids were made in the groundwater permeating Reclamation site 2 at the Canmore Coal Mine (Alberta, Canada). Estimates of the number of bacteria present in the groundwater were also made using plate and direct count techniques. Temperature, pH, Eh, and oxygen content of the groundwater were measured on two occasions. DOM was very low in concentration (av. 1.62 mg/liter) and consisted principally of fulvic acid. Humic acids formed about 20% of DOM, carbohydrates 6%, tannins + lignins 4%, and trace compounds (phenols, amino acids, and proteins) 2%. Seasonal variations were observed, with tannins + lignins and carbohydrates reaching their highest concentration in the summer, and humic and fulvic acids, and DOM peaking in the winter. The organic composition of the groundwater upstream of the reclamation site did not differ significantly from groundwater sampled from within the reclamation site. Differences were observed, however, between ground and surface waters draining the site. No correlation between concentration and depth was observed. Large numbers of bacteria were found in groundwater using both plate count and direct count methods. Populations were only modestly correlated with the concentrations of organic compounds (r<0.9). Heterotrophic bacteria must have been dependent upon organic matter (both as DOM and as insoluble organic matter in the spoil) for growth, however. The groundwater bacteria studied appeared to be characterized by slow growth under adverse geological conditions with only low concentrations of labile organic compounds present.     

Isolation of humic acid from the brown algaPilayella littoralis

A standard humic acid extraction procedure has been used to isolate dark brown organic residues from samples of the macroscopic marine brown algaPilayella littoralis. The residues are insoluble in water, but soluble at high pH, and are similar in elemental composition, ash content, UV-visible, IR, PMR and X-Ray fluorescence spectra, X-Ray diffractograms and scanning electron micrographs to residues of a humic acid isolated from municipal compost. These results indicate thatPilayella produces humic acids.Author for correspondence     

Seasonal changes in the concentration and colour of humic substances in some aquatic environments

SUMMARY. 1. Between February and September 1974, concentrations of fulvic and humic acids in waters from a cryoboreal region of the Precambrian Shield in Quebec varied between 0.5–6.1 mg 1⁻¹ and 0.1–6.5 mg 1⁻¹ respectively. Whereas the fulvic acids usually remained relatively constant during this period, humic acids showed appreciable increases.
2. The number and weight average molecular weights of the fulvic acids (∼5000 and ∼22,000 daltons respectively) were lower than those of the humic acids (∼20,000 and ∼75,000 daltons respectively). The average molecular weight of the aquatic humic matter often decreased during late summer and early autumn. During spring floods the molecular weight of fulvic acids increased and that of humic acids declined.
3. Because the aquatic humic acids were more intensely coloured than fulvic acids, they contributed more than 30% of the colour of the water even though they accounted for only 15% of the concentration of humic matter. The colour intensity of both fulvic and humic acids generally appeared to increase during the latter part of the summer, when there was normally a decrease in the value of the colour quotient (E₄/E₆ ratio), indicating the accumulation in the waters of more humified material.     

Extracellular enzyme activities of Bjerkandera adusta R59 soil strain, capable of daunomycin and humic acids degradation

Geotrichum-like strain R59, the anamorphic form of the white-rot fungus, Bjerkandera adusta, was isolated from soil. It was found to completely decolorize and degrade 10% daunomycin post-production effluent during 10 days of incubation at 26°C. Strain R59 produced only low levels of ligninolytic enzymes when grown on wheat straw- or beech sawdust-containing media, but in the presence of humic acids derived from brown coal it synthesized significant amounts of laccase and lipase. This phenomenon was coupled with the fungus entering the idiophase and the appearance of aerial mycelium. B. adusta strain R59 was found to completely decolorize 0.03% humic acids from brown coal and lessive soil and to partially decolorize humic acids isolated from a chernozem during 14 days of growth. This ability of strain R59 could be useful in constructing a new generation of biologically active filters for the purification of humic acids-contaminated drinking waters.     

Spectroscopic properties of dissolved humic substances - a reflection of land use history in a fen area

The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm^–1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.     

Effects of humic and fulvic acids on poliovirus concentration from water by microporous filtration

Because naturally occurring organic matter is thought to interfere with virus adsorption to microporous filters, humic and fulvic acids isolated from a highly colored, soft surface water were used as model organics in studies on poliovirus adsorption to and recovery from electropositive Virosorb 1MDS and electronegative Filterite filters. Solutions of activated carbon-treated tap water containing 3, 10, and 30-mg/liter concentrations of humic or fulvic acid were seeded with known amounts of poliovirus and processed with Virosorb 1MDS filters at pH 7.5 or Filterite filters at pH 3.5 (with and without 5 mM MgCl2). Organic acids caused appreciable reductions in virus adsorption and recovery efficiencies with both types of filter. Fulvic acid caused greater reductions in poliovirus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with poliovirus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced poliovirus recoveries by both types of filter, its greatest effect was on virus elution and recovery from Filterite filters. Single-particle analyses demonstrated MgCl2 enhancement of poliovirus association with both organic acids at pH 3.5. The mechanisms by which each organic acid reduced virus adsorption and recovery appeared to be different for each type of filter.     

Effects of humic and fulvic acids on poliovirus concentration from water by microporous filtration.

Because naturally occurring organic matter is thought to interfere with virus adsorption to microporous filters, humic and fulvic acids isolated from a highly colored, soft surface water were used as model organics in studies on poliovirus adsorption to and recovery from electropositive Virosorb 1MDS and electronegative Filterite filters. Solutions of activated carbon-treated tap water containing 3, 10, and 30-mg/liter concentrations of humic or fulvic acid were seeded with known amounts of poliovirus and processed with Virosorb 1MDS filters at pH 7.5 or Filterite filters at pH 3.5 (with and without 5 mM MgCl2). Organic acids caused appreciable reductions in virus adsorption and recovery efficiencies with both types of filter. Fulvic acid caused greater reductions in poliovirus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with poliovirus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced poliovirus recoveries by both types of filter, its greatest effect was on virus elution and recovery from Filterite filters. Single-particle analyses demonstrated MgCl2 enhancement of poliovirus association with both organic acids at pH 3.5. The mechanisms by which each organic acid reduced virus adsorption and recovery appeared to be different for each type of filter.     

Brown rot of wood as a model for studies of lignocellulose humification

Humus substances synthesis was investigated in the course of birch wood decomposition by a brown-rot fungusPiptoporus betulinus. With progressing decomposition of wood by brown rot the proportion of high molecular weight humic acids is gradually increased at the expense of fulvic acids, the amount of which is proportionally lowered. The high molecular weight humus constituents are not accumulated in wood decomposed by a laccase producing white-rot fungi despite the availability of suitable phenolic substrates; the low molecular weight fraction of fulvic acids is permanently higher than the fraction of humic acids. The function of laccase in lignin degradation and in biosynthesis of humic acids is problematic.     

Effects of humic and fulvic acids on growth of tobacco

Summary Organic matter was extracted with a mixture of 0.1M Na₄P₂O₇ and 0.1M NaOH from soil and a commercial organic matter product, Aqua Humus, and separated into humic and fulvic acids according to their solubility in acid and alkaline solutions. They were purified by passage through a cation exchange resin, freeze-dried, and used for characterization and seedling growth studies. The CEC increased with pH for both humic and fulvic acids. Data from tobacco seedling studies show that humic and fulvic acids from both sources increased root number and length at low concentrations while at high concentrations, humic acids inhibited length and number of roots but fulvic acids had no effect. The results support the proposition that fractions of organic matter referred to as humic and fulvic acids affect root development by means other than as a source of nutrients.     

<Emphasis Type="Italic">Hortaea acidophila</Emphasis>, a new acid-tolerant black yeast from lignite

A hitherto undescribed black yeast was isolated from an extract of brown coal containing humic and fulvic acids at pH 0.6. The fungus showed morphological similarity to some members of the genus Exophiala (Chaetothyriales) and of Hortaea (Dothideales). Based on SSU rDNA sequence similarity to meristematic members of the Dothideales, the new species was accommodated in Hortaea, which presently contains only a single, halophilic species, H. werneckii.     

Viscosimetric studies on molecular weight fractions of fulvic and humic acids of aquatic,terrestrial and microbial origin

Summary Viscosities were investigated of solutions of fulvic and humic acid molecular weight fractions of aquatic, terrestrial and microbial origin. Aquatic fulvic and humic acid molecules were, at pH 7, more voluminous than other types of humic compounds of similar molecular weight. It would appear that in low molecular weight non-aquatic humic matter, more inter- than intra-molecular bonding is present, with increasing molecular weight the bonding becomes more intra-molecular. Differences between average molecular weight values as obtained by an ultrafiltration method (Amicon) and by viscosimetry ranged from –18.7 to 18.5%. The largest deviations were in the low molecular weight range (<5,500 daltons). Higher molecular weight humics (in particular humic acids) appeared to have a more elongated structure than lower molecular weight material (in particular fulvic acids). Indications were obtained that on hydration humic moleculars become more elongated.     

Do acid-tolerant picocyanobacteria exist? A study of two strains isolated from humic lakes in Poland

The occurrence of picocyanobacteria, the smallest cell-size fraction of cyanobacteria, in low-pH waters, is still poorly studied. In this study, we tested the hypothesis that picocyanobacteria found occasionally in low-pH environments are adapted to such water conditions. We isolated picocyanobacteria by means of the cytometric method from two humic lakes with pH ≤5. We obtained two strains belonging to two cosmopolitan phylogenetic clades of picocyanobacteria: Cyanobium gracile cluster and Subalpine cluster I. Experiments on filtered lake water from low-pH (≤5) and slightly alkaline (pH 8.2) lakes, and with an acidified cyanobacterium medium (pH 4.5) were conducted to test the growth of the isolated picocyanobacteria in various pH conditions. The experimental results of this study showed that some picocyanobacteria strains were acid tolerant, achieving higher growth rates and reaching higher maximum numbers in humic, naturally acidic waters rather than in alkaline waters. We show that despite a close phylogenetic relationship, strains of picocyanobacteria exhibit significant physiological and ecological diversity and that at least some picocyanobacteria have the evolutionary potential to cope with low pH. Characterization of the genetic basis of acid tolerance in picocyanobacteria is important to understand how these microorganisms function in aquatic ecosystems and how their communities may respond to a changing environment.     

Survival and Reproduction of Some Nematodes as Affected by Muck and Organic Acids

Fulvic, humic, acetic, N-bulyric, formic, lactic, and propionic acids were inhibitory to the survival or reproduction of Aphelenchus avenae, Aphelenchoides goodeyi, Helicotylenchus pseudorobustus, Meloidogyne hapla or Xiphinema americanum. Reproduction of H. pseudorobustus and M. hapla significantly increased with increasing amounts of muck added to sand, and with the initial amount of nematode inoculum. All acids except humic and fulvic were lethal, in vitro, to all nematode species tested. When A. goodeyi was treated with fulvic acid, reproduction was reduced significantly when compared with sodium humate or water treatments. Treatment of H. pseudorobustus with fulvic acid (pH 3.5) resulted in a greater reduction in reproduction in soil than did treatment with humic acid (pH 3.5).     

Effect and potential ecological significance of the interaction of humic acids with two aquatic extracellular proteases

1. The effects of humic acids and fulvic acids on an extracellular serine and metalloprotease purified from a strain of Aeromonas hydrophila isolated from a freshwater wetland were examined. The serine protease was inhibited by humic acids at pH and humic acid concentrations found naturally in the wetland where this strain of A. hydrophila was isolated. The metalloprotease was not inhibited by humic acids at any pH investigated. Fulvic acids had no effect upon either protease. 2. Inhibition of serine protease activity by humic acids was reversed by increasing the pH to 9, as well as increasing the ionic strength by addition of CaCl₂- It was concluded that the interaction between humic acids and the serine protease was primarily ionic. 3. The formation of a humic acid-serine protease complex increased the half-life of enzymatic activity in dilute solutions. Humic acids had no effect on the stability of the metalloprotease. 4. There was no clear effect of humic acids on the growth of A. hydrophila, indicating that either the serine protease is not involved in the rate-limiting step of growth or that sufficient activity exists even when the serine protease is inhibited by humic acids. 5. Increasing the enzymatic lifetime through association with humic acids may be an adaptive mechanism which could result in energy conservation due to a decreased requirement for protein synthesis.     

The influence of humic substances on the aerobic decomposition of submerged leaf litter

Leaf material was incubated in flasks containing streamwater in which the pH and the concentration of isolated fulvic acid were varied independently of one another. Decomposition of the leaf material was slower at pH 4 than at pH 5 or 7, but the concentration of fulvic acid had no effect when the pH was held constant. At pH 5, 20 mg Cl^–1 humic acid also had no effect on decomposition. High concentrations of dissolved fulvic acids may contribute to the slow decomposition of plant litter characteristic of many wetlands through their contribution to hydrogen ion activity, but we could find no evidence for other properties of fulvic acid which inhibit leaf litter decomposition.     

Recherches hydrobiologiques au lac Tumba (Congo Belge,Province de l'Equateur)

Summary Lake Tumba is a shallow lake situated in the Congo basin near the Equator. Its area is about 191.250 acres. It gets its waters from different rivers and the surplus is shed into the Congo River, through the Irebu Channel, a little south-west from Coquilhatville. The maximum depth is about 8 meters and the mean depth is 3 to 5 meters (see bathymetric map).The waters are very rich in humic substances, owing to their origin in the forest soils around the lake. Its acid and brown waters are poor in true phyto-and zooplancton. The bottom is hard, made of kaolin and sand, without mud and as a matter of consequence, the bottom fauna is very poor. There is oxygen in the water down to the bottom at any time.The coasts are covered with a thick forest and dead leaves, branches and tree trunks contribute much foodstuff to the waters. This makes it possible for this lake to be rather rich in fish. Sixty six species of fishes are listed for the lake itself and ten species for the swamps or the flooded forest which, at high waters, communicate with the lake. Their food relations are described.As mature fish is very rare in the lake, the hypothesis has been made that, at high waters, the fishes migrate into the flooded forests and swamps around the lake when maturity comes. Breeding would happen in the inundated areas and the fish would return afterwards to the lake.A discussion is given about the origin of lake Tumba. Morphology of the lake, Chemistry of the waters and nearly complete lack of endemic species and of pelagic life point to a recent origin.The hypothesis is advanced that lake Tumba would be the result of the damming of an affluent of the Congo River and not the residue of the slow evaporation of an ancient central african lake.     

Use of measurement of liver cytochrome P 450 as a water toxicity test]

The authors describe a new approach to determine the toxicity of water samples. The level of liver hydroxylating cytochrome in mice injected with water samples is assayed. This assay is used to test the toxicity of waters containing an earth extract (humic and fulvic acids). The water samples showed various toxicities desinfected with chlorine or ozone.