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Chapter 23 of the book "Handbook of Water & Wastewater Microbiology" is presented. It explores the microbiology of phosphorus removal in activated sludge. It states that activated sludge systems are an integral part of municipal wastewater treatment. To prevent eutrophication in these systems, phosphate removal is necessary. Biological phosphorus removal techniques such as culture based techniques and fluorescent in situ hybridization (FISH) are also presented.

Among the issues confronting activated sludge researchers are the assessment of the active biomass mediating the process and the delineation of the key microbial groups comprising the total population. More specific to biological excess phosphate removal (BEPR) is the quantification of that portion of the population responsible for the release and subsequent uptake of soluble phosphate-the polyphosphate accumulating organisms (PAO's). This study attempts to address these questions by investigating the active microbial community within pilot- and full-scale BEPR systems. Microbial community analysis was conducted on the full-scale plant using fluorescent in situ hybridization (FISH) and dot blots. The alpha and beta Proteobacteria were found to dominate this activated sludge population. Enrichment procedures performed on a continuous pilot-scale plant designed to enhance the growth of PAO's, followed by probing with fluorescently labeled oligonucleotides, also showed the alpha and beta Proteobacteria to be dominant. This study shows how the application of FISH can be used for determining that fraction of the measured volatile suspended solids (VSS) present as total active biomass (Xa) and PAO's (XPAO). [ABSTRACT FROM AUTHOR]

The activated sludge used in the biological treatment of polluted water is a typical ecosystem composed of bacteria and protozoa. There should be an indigenous picture of competition, predation, mutualism and so forth, among the microorganisms which contribute to the removal of organic matters from polluted waters. Specific protozoa have been detected in the sludge when the process proceeds satisfactorily. Therefore, a study how to control the protozoan fauna in the sludge to warrant a good quality of effluent is essential. This article presents a clue leading to the microbiological control of the biotic community in the sludge, through the studies on ecological characteristics in the monoxenic culture of ciliated protozoa isolated from the activated sludge. [ABSTRACT FROM AUTHOR]

The article reviews the present understanding of bacterial populations involved in anaerobic degradation of organic material into methane and CO2 (biogas); furthermore some recent process developments for anaerobic wastewater treatment are described. It could be demonstrated that at least three groups of bacteria are involved in methanogenesis. Hydrolytic and acidogenic bacteria first decompose the organic material into various organic acids, alcohols, hydrogen and CO2. The second group of bacteria convert these metabolites into acetic acid, hydrogen and CO2, which are then utilized by the methanogenic bacteria to produce biogas. On an industrial scale, this process has been used for more than 50 years in the stabilization of sewage sludge from municipal water treatment plants. Since recent developments have markedly reduced the retention time for anaerobic fermentation*, this process has gained increasing interest in the treatment of high strength wastewater. The anaerobic digestion has two unique advantages over the aerobic biological treatment systems: no energy is necessary for aeration and the organic pollutants are mainly converted into biogas which can be used as a fuel. Until now this anaerobic process is successfully used for treatment of wastewaters from sugar factories, potato-processing industry and breweries. However, fundamental studies have shown that anaerobic treatment offers an enormous potential for the removal of organic materials from a lot of different wastewaters. Therefore, in future the application of anaerobic digestion for wastewater treatment will increase. [ABSTRACT FROM AUTHOR]

Thiamine added to a vitamin B6-free medium was accumulated in the free form in Saccharomyces yeast cells, and caused growth inhibition and respiratory deficiency under aerobic conditions. The thiamine-induced respiratory deficiency occurred as the result of a sequence of events as follows: (1) a decrease in vitamin B6 content, (2) a reduction in the activity of δ-aminolevulinate synthase, (3) heme deficiency, (4) cytochrome deficiency, and (5) respiratory deficiency. However, the growth inhibition was shown to be partially due to the respiratory deficiency, and the participation of some other events caused by the thiamine-induced vitamin B6 deficiency was suggested. The cytochrome deficiency also caused alteration in lipid composition; unsaturated fatty acid content was decreased and sterol composition was changed. Associated with the respiratory deficiency, the activity of NAD-linked glutamate dehydrogenase was decreased. In contrast, the NADP-linked enzyme activity was markedly increased. It was suggested that this increase was not caused by the respiratory deficiency but by a thiamine-enhanced glucose effect. The thiamine-grown cells showed an altered amino acid pool. Reflecting the respiratory deficiency, the thiamine-grown cells showed elevated activities of glycolysis and ethanol production. It was, however, suggested that the glycolytic rate was not determined by-phosphofructokinase activity, and ethanol production was controlled independently of glycolytic activity in the thiamine-supplemented culture. [ABSTRACT FROM AUTHOR]

Of the various immobilization methods available at present, entrapment of biocatalysts in natural or synthetic polymer gels is the most promising because of its applicability to the immobilization not only of single enzymes but also of plural enzymes, cellular organelles, microbial cells, plant cells and animal cells. This review summarizes novel and convenient methods of entrapping biocatalysts by using synthetic prepolymers of different chemical structures and physico-chemical properties. Emphasis is placed on the effects of the physico-chemical properties of gels prepared from various prepolymers which have different properties — network size, hydrophilicity-hydrophobicity balance and ionic nature — on the catalytic activities of the thus-entrapped biocatalysts. Bioconversions of hydrophobic or water-insoluble compounds by entrapped biocatalysts under hydrophobic conditions are also mentioned. [ABSTRACT FROM AUTHOR]

Rapid advances have been made in recent years in plant protoplast technology and research applications. Isolated protoplasts have been used successfully in virology and cell genetics. Protoplast fusion is feasible and a variety of hybrid cells of different plant genera have been produced. Somatic hybridization and hybrid plant formation have been achieved. The hybrids between several plant species and genera possess diversity in chromosome number and reflect the parental species in isoenzyme patterns. Genetic complementation occurs and cytoplasmic inherited factors such as male sterility are transferred through somatic hybridization. The protoplast fusion methods are being implemented in plant breeding procedures to achieve gene transfer between plants which cannot be crossed sexually and for the purpose of achieving more effective disease resistance. Transfer of genetic information using protoplasts also has been investigated by DNA uptake, which may require a vector such as plasmids or viral DNA. Moreover, organelle and single cell uptake/fusion is being pursued with plant protoplasts. Technological and biological obstacles at present restrict the application of recombinant DNA and organelle transplant procedures in plant research and development but new and significant advances can be anticipated in the next few years. [ABSTRACT FROM AUTHOR]

One of the specific features of alkane-utilizing yeasts is the conspicuous appearance of peroxisomes. This review describes the metabolism of alkanes in yeasts with special emphasis on the physiological function of peroxisomes. The subtle diversity in alkane utilization pathway in yeasts is mediated by subcellular localization of enzymes. In microsomes, alkanes are hydroxylated to the corresponding fatty alcohols which are further oxidized to fatty acids via aldehydes in microsomes, mitochondria and peroxisomes, respectively. Degradation of fatty acids to acetyl-CoA via the β-oxidation pathways is carried out exclusively in peroxisomes while fatty acids formed in microsomes and mitochondria are incorporated into cellular lipids, each after being activated to acyl-CoAs. Acetyl-CoA produced in peroxisomes is converted to C4-compounds by the cooperative action of peroxisomes and mitochondria. Some regulation of enzymes in alkane-assimilating yeasts is also discussed. [ABSTRACT FROM AUTHOR]

The different primary oxidation steps of long-chain aliphatic hydrocarbons by microorganisms and the pathways of degradation are reviewed. Furthermore, the occurrence of the different degradation pathways in microorganisms is described. Some relations with regard to taxonomy of microorganisms can be observed. In the concluding remarks lacks of our knowledge of microbial alkane oxidation are described. Especially, data are missing on the primary oxidation steps, on enzymes of the different pathways and on the regulation of alkane oxidation in most microorganisms. [ABSTRACT FROM AUTHOR]

Biochemical reactors are treated as heterogeneous catalytic reactors in which physical mass transfer completely or significantly controls the overall rate of the process being promoted in the reactor. The treatment used to develop basic design strategies takes into account the special constraints imposed by biological and biochemical phenomena on the systems. By identifying the fundamental principles involved, generalized mass transfer criteria for biochemical reactors are developed for both inter-particle and intra-particle pathways in solid-fluid and fluid-fluid contacting systems for such diverse processes as aerobic fermentations, anaerobic fermentations, immobilized enzyme reactions, and insoluble substrate utilization. A wide range of practical operating conditions extending from Theologically simple non-viscous materials to complex viscous non-Newtonian and multiphase systems, and from geometrically simple bubble-column and packed-bed devices to complex stirred-tank and tubular-loop configurations are considered. Recent advancements in the development of correlations for mass transfer coefficients, interfacial areas, and related parameters are reviewed. The processing energy required to induce and maintain the physical mass transfer pathways in the various reactor systems are also considered. It is shown that with the present state of the art, the application of engineering correlations to the scaling-up of biochemical reactors, especially stirred-tank reactor types, is more difficult than may be generally realized. Finally, attention is drawn to the areas of ignorance which need further exploration to help in the establisment of rational design and operation procedures for biochemical reactors. [ABSTRACT FROM AUTHOR]

Highly viscous media often occur in biotechnology, fermentation and food processing industries as well as in chemical and pharmaceutical industries. The present paper considers the behavior of aerated highly viscous media employing stirred tank reactors, sparged single and multistage tower reactors. Measuring methods to determine rheological properties, hydrodynamical behavior, power input, and mass transfer as well as behavior of single bubbles and bubble swarm are reviewed. Hydrodynamical properties, power inputs, oxygen transfer rates, volumetric mass transfer coefficients and heat transfer coefficients are considered as a function of the mean operating parameters employing stirred tank reactors with different impellers. Also sparged single and multistage tower reactors are treated, especially hydrodynamical properties, oxygen transfer rates and volumetric mass transfer coefficients. Relationships are given to lay out stirred tank and tower reactors with highly viscous media. [ABSTRACT FROM AUTHOR]