Jacques A. Soddell

Studies on filamentous bacteria from australian activated sludge plants

Abstract In a survey of activated sludge plants in Australia, where both foams and mixed liquor samples were examined, the organism most frequently dominant in both was Microthrix parvicella. Although Nocardia amarae-like organisms and Nocardia pinensis were often seen as dominant organisms in foams, they only rarely occurred as dominants in mixed liquor samples from the same plants. Instead, Types 0041/0675, 0092 and Haliscomenobacter hydrossis were more usually present. There appeared to be little relationship between filament community composition and plant operating parameters, and most filament types were seen in plants with diverse characteristics. Partial success was achieved in isolating a few of these filaments in pure culture, although in some cases, the media successfully used in other studies did not support their growth here. Their morphological properties are described.

A survey of filamentous bacterial populations from foaming activated sludge plants in Eastern States of Australia

Abstract Of 129 activated sludge plants surveyed during 1988 in Queensland, New South Wales and Victoria, 66 had a foam problem during the sampling period. Filament identification revealed that Microthrix parvicella, Nocardia amarae and Nocardia pinensis were the most commonly found, followed by Eikelboom types 0092, 0914 and 0041/0675, although their relative frequencies varied from state to state.

New foam-forming nocardioforms found in activated sludge

In a numerical taxonomic survey of foam-forming actinomycetes, representatives of four groups were selected for further taxonomic study because they either did not cluster with known reference strains of nocardioforms or their relationship to them was uncertain. Phylogenetic studies, using 16S rDNA sequencing, showed that one group probably represented a previously described species, Rhodococcus erythropolis , but two possibly represented new species of Gordona and Rhodococcus . The fourth group represented an independent line of descent, possibly a new genus. These, together with strains of foam-formers Gordona amarae and Skermania piniformis , were evaluated for their growth on hydrophobic substrates likely to be found in activated sludge plants. All grew well on vegetable oils (olive, safflower and coconut) and on mixtures of hydrocarbons like paraffin oil, but at varying rates. However, growth on kerosene and hexadecane was less consistent. One feature of growth on the hydrophobic substrates was the attachment of most cells to the hydrophobic substrate rather than growth in the aqueous phase. This suggests a possible method for competing for nutrients with faster-growing (but not hydrophobic) organisms in activated sludge.

Relationship between temperature and growth of organisms causing Nocardia foams in activated sludge plants

Abstract Foaming, an operational problem in activated sludge plants, is commonly caused by actinomycetes of the genera Nocardia, Rhodococcus, Gordona, Tsukamurella and Mycobacterium , and such foams are often referred to as Nocardia foams. This paper addresses conflicting reports about the temperature at which foaming occurs by determining the temperatures at which various nocardioforms will grow in pure culture. Strains tested included foam isolates, type strains of organisms reported in the literature to be involved in foaming, and type strains of related actinomycetes. The data showed that all three categories contained organisms that grew at 5°C, and these were principally Rhodococcus spp. Thus the so-called Nocardia foams at low temperatures are more likely to be caused by Rhodococcus species. Although some foam isolates, especially Nocardia pinensis , grew over a relatively narrow range of temperatures, this growth range is still sufficient for them to cause problems in many plants. A few isolates grew at 40°C or higher, suggesting these were more likely to occur in plants treating warm wastewater or possibly could grow in foam where ambient air temperature is high.

Incidence and morphological variability of nocardia pinensis in australian activated sludge plants

Abstract Organisms exhibiting the typical microscopic branching patterns of Nocardia pinensis were seen in samples from 18/69 foaming and 13/75 non-foaming Australian activated sludge plants covering a wide geographic and climatic area. Although considerable variations in their morphology were observed under the microscope, particularly with respect to their branching angles, branch lengths and interbranch distances, pure cultures obtained by micromanipulation from 27 of these plants were remarkably consistent in their morphological and physiological properties, corresponded to previously described isolates of Nocardia pinensis , and were easily differentiated from 25 control cultures of related organisms using the API ZYM system. N. pinensis is readily differentiated from other “nocardias” when activated sludge samples are examined microscopically and should be reported separately.

Metabolic variation among strains of Acinetobacter isolated from activated sludge

When the carbon substrate utilisation profiles of a large number of Acinetobacter isolates from a biological nutrient removal plant were determined using the Biolog system considerable variation was seen, even within individual genospecies. Only a very small percentage of isolates had identical patterns. Similar diversity was also seen in the ability of these strains to synthesise poly β hydroxybutyrate and polyphosphate in pure culture. Such data must raise questions about the current models for biological phosphorus removal, based as they are on an incomplete understanding of the physiology of Acinetobacter strains from waste treatment systems.

Identification of Acinetobacter isolates using the Biolog identification system

The Biolog system was assessed for its ability to identify genospecies of Acinetobacter from a wastewater treatment plant. A success rate of 83% was achieved in identifying to genus level, but different genospecies identifications were obtained, with the possible exception of genospecies 7, when the results were compared with other published phenotypic identification schemes.

The opportunistic pathogen Nocardia farcinica is a foam-producing bacterium in activated sludge plants.

H.M. STRATTON, R.J. SEVIOUR, J.A. SODDELL, L.L. BLACKALL AND D. MUIR. 1996. A Grampositive unicellular coccal‐diphtheroid rod causing foam in an activated sludge plant was successfully isolated by micromanipulation. Phenotypic characterization and 16S rDNA sequencing identified it as Nocardia farcinica. This is the first report that this opportunistic pathogen is a foam‐causing bacterium in activated sludge, and the clinical implications of these observations are discussed.

Diversity of isolates of Acinetobacter from activated sludge systems based on their whole cell protein patterns

Whole cell protein extracts from strains of the currently recognized genomic species of Acinetobacter, together with those from a range of isolates of several genomic species identified using the Biolog system and obtained from a biological nutrient-removal activated sludge plant were analysed by SDS-PAGE. The dendrograms obtained after numerical analysis for the known genomic species generally supported the taxonomic relationships suggested from earlier DNA–DNA hybridisation data. In some cases the activated sludge isolates identified to genomic species level clustered closely with the corresponding genomic species reference strains, although isolates 5 and 8/9 were scattered throughout the dendrogram. Considerable variations were seen in the protein patterns of the 27 different environmental isolates of genomic species 7 that were analysed. Three unidentified Acinetobacter isolates examined formed their own subcluster.

Development of the microbial community of a full scale biological nutrient removal activated sludge plant during start-up

Abstract The bacterial populations capable of accumulating polyphosphate in pure culture were followed during the first 10 months of operation of a full scale biological nutrient removal plant with a modified U.C.T. configuration. Special emphasis was placed on the Acinetobacter isolates obtained. Results showed that of these, most could be identified as A. johnsonii (genospecies 7) although other genospecies including 9 and 12 were also found in smaller numbers. A large number of these could not be identified with the Biology system. Several other Gram positive and Gram negative bacterial genera capable of removing polyphosphate were also isolated from the biomass. The filamentous bacterial populations seen in the mixed liquor and foam were monitored regularly over this period, and after early changes, Microthrix parvicella and Eikelboom Types 0092 and 0041/0675 gradually assumed dominance in the mixed liquor, while Nocardia amarae-like organisms and Type 0092 together with M. parvicella were in the foam.