Distribution of inland wetlands with sulfidic sediments in the Murray-Darling Basin, Australia.

This project examined the extent of sulfidic sediments in freshwater wetlands of the Murray-Darling Basin, Australia. We sampled 81 wetlands throughout the basin with methods previously developed for the analysis of coastal acid sulfate soils. Sulfidic sediments are generally regarded as a coastal phenomenon. We tested the hypothesis that elevated concentrations of mineral sulfides may also accumulate in sediments of inland wetlands. Of the 81 wetlands sampled, 17 (21%) contained reduced sulfur in sediments at concentrations above suggested trigger values. Most of the affected wetlands were adjacent to the Murray River, with only several associated with other major river catchments. Reduced sulfur in the sediments was positively correlated with sulfate concentrations in the overlying water column. This represents a concern for wetland managers because of the increasing desire to return wetlands to a more natural wetting and drying cycle to improve wetland health. However, during drying, sulfidic sediments oxidise and produce acid, which may exceed the buffering capacity of the system and ultimately harm aquatic life. Therefore, if sulfidic sediments are present, a drying phase should only be reinstated after careful consideration of the potential acidification risks. This study verified that sulfidic sediments can occur in freshwater wetlands in concentrations that could pose an ecological risk if mismanaged.

A simple, reproducible substrate for studying biofilms in aquatic environments.

In this paper we present a simple in expensive substrate for studying biofilms. Bioballs are robust plastic spheres with high surface area to volume ratios (ca 130:1) used in home aquarium filters. Their properties make them ideal substrates for use in studies of aquatic biofilms. As examples, in this paper we describe the growth and enzyme activities of biofilms grown on these substrates and explore the interaction between DOC concentration and biofilm biomass. Biofilm growth and activity on the bioballs was very reproducible. For example maximum biofilm growth following approximately 3 months inundation was estimated to be 40 (+/- 3.6) mg protein and 120 (+/- 11) microg chlorophyll a per bioball.

Desulforegula conservatrix gen. nov., sp. nov., a long-chain fatty acid-oxidizing, sulfate-reducing bacterium isolated from sediments of a freshwater lake.

A novel sulfate-reducing bacterium, strain Mb1PaT, was isolated from the sediments of a freshwater floodplain lake. Cells of strain Mb1PaT were rod-shaped, 1-1.3 microm wide and 2.6-3 microm long, motile and Gram-negative. The bacterium grew on straight-chain carboxylic acids with 4-17 carbon atoms. Electron donors with an even number of carbon atoms were oxidized to acetate and electron donors with an odd number of carbon atoms were oxidized to acetate and propionate. No other compounds were found to be used as electron donors. No growth occurred in the absence of sulfate. The optimum temperature for growth was between 25 and 30 degrees C and the maximum temperature for growth was 32 degrees C. Strain Mb1PaT grew very slowly in medium with 5 g NaCl l(-1) with optimum growth occurring with up to 1.0 g NaCl l(-1). Analysis of the 16S rRNA gene showed that strain Mb1PaT belonged to the delta-subclass of the Proteobacteria, was a member of the family Desulfobacteraceae, but lacked similarity with any currently described representatives. The combined phylogenetic analysis and physiological data indicate that strain Mb1PaT represents a new genus and the name Desulforegula conservatrix is proposed. The type strain is Mb1PaT (= DSM 13527T = ATCC BAA-134T).

Structure and functional analysis of the microbial community in an aerobic: anaerobic sequencing batch reactor (SBR) with no phosphorus removal.

The bacterial community of an aerobic:anaerobic non-P removing SBR biomass fed a mixture of acetate and glucose was analysed using several 16S rRNA based methods. Populations responsible for anaerobic glucose and acetate assimilation were determined with fluorescent in situ hybridization (FISH) in combination with microautoradiography (FISH/MAR). At 'steady state' this community consisted of alpha-Proteobacteria (26%) and gamma-Proteobacteria (14%), mainly appearing as large cocci in tetrads (i.e. typical 'G-Bacteria'). Large numbers of low G+C bacteria (22%), and high G+C Gram-positive bacteria (29%) seen as small cocci in clusters or in sheets were also detected after FISH. DGGE fingerprinting of PCR amplified 16S rDNA fragments and subsequent cloning and sequencing of several of the major bands led to the identification of some of these populations. They included an organism 98% similar in its 16S rRNA sequence to Micropruina glycogenica, and ca. 76% of the high G+C bacteria responded to a probe MIC 184, designed against it. The rest responded to the KSB 531 probe designed against a high G+C clone sequence, sbr-gs28 reported in other similar systems. FISH analyses showed that both these high G+C populations were almost totally dominated by small clustered cocci. Only ca. 2% of cells were beta-Proteobacteria. None of the alpha- and gamma-Proteobacterial 'G-bacteria' responded to FISH probes designed for the 'G-Bacteria' Amaricoccus spp. or Defluvicoccus vanus. FISH/MAR revealed that not all the alpha-Proteobacterial 'G-Bacteria' could take up acetate or glucose anaerobically. Almost all of the gamma-Proteobacterial 'G-Bacteria' assimilated acetate anaerobically but not glucose, the low G+C clustered cocci only took up glucose, whereas the high G+C bacteria including M. glycogenica and the sbr-gs28 clone assimilated both acetate and glucose. All bacteria other than the low G+C small cocci and a few of the alpha-Proteobacteria accumulated PHB. The low G+C bacteria showing anaerobic glucose assimilation ability were considered responsible for the lactic acid produced anaerobically by this SBR biomass, and M. glycogenica for its high glycogen content.

Saccharococcus caldoxylosilyticus sp. nov., an obligately thermophilic, xylose-utilizing, endospore-forming bacterium.

Several closely related, xylanolytic, thermophilic bacilli were isolated from local soils on xylose-containing minimal medium. On the basis of morphology and biochemical characteristics, one of the isolates, designated strain S1812T (T = type strain), was studied further. Strain S1812T was a xylanolytic, sporulating, Gram-positive, rod-shaped bacterium. Its Gram-positive nature was confirmed by electron microscopic examination of thin sections of the cells. The isolate was a thermophilic (optimum temperature for growth, 65 degrees C), facultative anaerobe that grew on a wide range of carbon sources including glucose, lactose, starch and xylose. It expressed high levels of both xylose isomerase and xylulokinase on xylose and also on glucose. The DNA G + C content was 44 mol%. rRNA gene sequence analysis placed strain S1812T in Bacillus cluster 5; it was more closely related to Saccharococcus thermophilus than to thermophilic Bacillus species. DNA-DNA hybridization also indicated its close relationship to S. thermophilus. Based on the evidence presented, it is proposed that strain S1812T be designated Saccharococcus caldoxylosilyticus sp. nov. Strain S1812T is the type strain (= ATCC 700356T = DSM 97-987T).

Friedmanniella spumicola sp. nov. and Friedmanniella capsulata sp. nov. from activated sludge foam: gram-positive cocci that grow in aggregates of repeating groups of cocci.

Two Gram-positive, non-motile, non-spore-forming, strictly aerobic, pigmented cocci, strains Ben 107T and Ben 108T, growing in aggregates were isolated from activated sludge samples by micromanipulation. Both possessed the rare type A3 gamma' peptidoglycan. Major menaquinones of strain Ben 107T were MK-9(H4) and MK-7(H2), and the main cellular fatty acid was 12-methyltetradecanoic acid (ai-C15:0). In strain Ben 108T, MK-9(H4), MK-9(H2) and MK-7(H4) were the menaquinones and again the main fatty acid was 12-methyltetradecanoic acid (ai-C15:0). Polar lipids in both strains consisted of phosphatidyl inositol, phosphatidyl glycerol and diphosphatidyl glycerol with two other unidentified glycolipids and phospholipids also present in both. These data, together with the 16S rDNA sequence data, suggest that strain Ben 107T belongs to the genus Friedmanniella which presently includes a single recently described species, Friedmanniella antarctica. Although the taxonomic status of strain Ben 108T is far less certain, on the basis of its 16S rRNA sequence it is also adjudged to be best placed in the genus Friedmanniella. The chemotaxonomic characteristics and DNA-DNA hybridization data support the view that Ben 107T and Ben 108T are novel species of the genus Friedmanniella. Hence, it is proposed that strain Ben 107T (= ACM 5121T) is named as Friedmanniella spumicola sp. nov. and strain Ben 108T (= ACM 5120T) as Friedmanniella capsulata sp. nov.

Tessaracoccus bendigoensis gen. nov., sp. nov., a gram-positive coccus occurring in regular packages or tetrads, isolated from activated sludge biomass.

An isolate of a Gram-positive bacterium, designated strain Ben 106T, was obtained in pure culture by micromanipulation of a biomass sample obtained from a laboratory-scale sequencing batch reactor. This isolate grew axenically as cocci or clusters of cocci arranged in regular tetrads and was morphologically similar to the dominant organism observed in the biomass. This morphology resembled that of some Gram-positive and -negative bacteria and the so-called 'G-bacteria' commonly seen in activated sludge samples. Strain Ben 106T is a non-motile, facultative anaerobe. It is oxidase-negative, catalase-positive and is capable of reducing nitrate. This organism can grow between 20 and 37 degrees C, with an optimum temperature of 25 degrees C. The pH range for growth is between 6.0 and 9.0, with an optimum pH of 7.5. The isolate stained positively for intracellular polyphosphate granules. The diagnostic diamino acid of the peptidoglycan is LL-diaminopimelic acid (LL-A2pm) with a glycine moiety at position 1 of the peptide subunit, which characterizes the presence of a rare peptidoglycan (type A3-gamma'). Two menaquinones, MK-9(H4) and MK-7(H4), are present and the main cellular fatty acid is 12-methyltetradecanoic acid. The G + C content is 74 mol%. From phenotypic characteristics and 16S rDNA sequence analysis, the isolate differed sufficiently from its closest phylogenetic relatives, namely Propionibacterium propionicum, Propioniferax innocua, Friedmanniella antarctica, Luteococcus japonicus and Microlunatus phosphovorus in the A1 subdivision of the Gram-positive bacteria (i.e. Firmicutes with a high G + C content), suborder Propionibacterineae, to be placed in a new genus, Tessaracoccus, as Tessaracoccus bendigoensis gen. nov., sp. nov. The type strain is Ben 106T (= ACM 5119T).

Apparent bioaccumulation of Mn derived from paper-mill effluent by the freshwater crayfish Cherax destructor--the role of Mn oxidising bacteria.

Bioaccumulation studies of wastewater from a thermo-mechanical paper mill using the freshwater crayfish (Cherax destructor) consistently demonstrated elevated levels of manganese. Most of the Mn appeared to be associated with the carapace of the animals. It is suggested that the elevated Mn levels are the result of Mn-oxidising bacteria forming biofilms on the carapace of the crayfish followed by Mn oxide precipitation rather than active uptake of Mn by the crayfish.

Amaricoccus gen. nov., a gram-negative coccus occurring in regular packages or tetrads, isolated from activated sludge biomass, and descriptions of Amaricoccus veronensis sp. nov., Amaricoccus tamworthensis sp. nov., Amaricoccus macauensis sp. nov., and Amaricoccus kaplicensis sp. nov.

Three isolates of gram-negative bacteria, strains Ben 102T, Ben 103T, and Ben 104T, were obtained in pure culture by micromanipulation from activated sludge biomass from wastewater treatment plants in Italy, Australia, and Macau, respectively. These isolates all had a distinctive morphology; the cells were cocci that usually were arranged in tetrads. Based on this criterion, they resembled other bacteria from activated sludge previously called "G" bacteria. On the basis of phenotypic characteristics and the results of 16S ribosomal DNA sequence analyses, the three isolates were very similar to each other, but were sufficiently different from their closest phylogenetic relatives (namely, the genera Rhodobacter, Rhodovulum, and Paracoccus in the alpha subdivision of the Proteobacteria) to be placed in a new genus, Amaricoccus gen. nov. Each of the three isolates represents a new species of the genus Amaricoccus; strains Ben 102T, Ben 103T, and Ben 104T are named Amaricoccus veronensis, Amaricoccus tamworthensis, and Amaricoccus macauensis, respectively. An isolate designated Ben 101T, which was isolated independently by Cech and Hartman in Kaplice, Czech Republic, was also characterized and belongs to the same genus. We propose that the isolate of Cech and Hartman should be placed in another new species, Amaricoccus kaplicensis.

Anaerobaculum thermoterrenum gen. nov., sp. nov., a novel, thermophilic bacterium which ferments citrate.

A thermophilic anaerobic bacterium designated strain RWcit2T (T = type strain) was isolated from the production water of a petroleum reservoir. The cells of this organism are straight to slightly curved rods that are gram negative and nonmotile. Spore formation has not been demonstrated. Growth occurs at temperatures ranging from 28 to 60 degrees C, with optimum growth occurring at 55 degrees C, and at pH values ranging from 5.5 to 8.6, with optimum growth occurring between pH 7 and 7.6. Growth occurs in media containing 0 to 20 g of NaCl per liter, and optimum growth occurs in the presence of 10 g of NaCl per liter. Strain RWcit2T grows on a range of organic acids, including citrate, pyruvate, malate, fumarate, and tartrate; on protein extracts; and on a limited number of carbohydrates. Sulfur, thiosulfate, and cystine are reduced to hydrogen sulfide. Sulfate, sulfite, and nitrate are not reduced. The DNA base composition is 44 mol% G + C. The 16S ribosomal DNA sequence revealed that strain RWcit2T is a member of the domain Bacteria and forms a branch that is approximately equidistant from Dictyoglomus thermophilium and Thermoanaerobacter spp. (level of similarity, 82%). Strain RWcit2T cannot be placed in any previously described taxon based on its phylogenetic and physiological traits and is named Anaerobaculum thermoterrenum gen. nov., sp. nov.

Differentiation of polyphosphate and poly-beta-hydroxybutyrate granules in an Acinetobacter sp. isolated from activated sludge.

Cells containing polyphosphate 71 micrograms P (mg protein)-1 and no poly-beta-hydroxybutyrate showed metachromatic granules but no lipid granules; cells containing poly-beta-hydroxybutyrate (15% of dry weight) showed fluorescence lipid granules but no metachromatic granules; whereas cells containing both polyphosphate and poly-beta-hydroxybutyrate showed both types of granules. These observations, together with a critical review of the literature, show a clear distinction between metachromatic (or volutin) granules and lipid granules.