The sugar industry processes sugar cane and sugar beet to manufacture edible sugar. A high rate anaerobic system followed by an activated sludge process to 'polish' the effluent is presently the best available technology not entailing excessive costs for the treatment of wastewater from sugar processing factories. Upflow anaerobic sludge blanket (UASB) reactor systems are the most commonly implemented, with the higher loaded expanded granular sludge bed (EGSB) type systems gradually replacing at least some of the UASB applications. This higher loading carries with it a greater risk of process instability, especially given the irregular quantity and composition of sugar processing wastes. Control actions are required for process efficiency, preferably with appropriate control parameters monitored on-line. The need to balance economics (with regards to quantities of chemicals dosed) with the safety/stability of the process further exacerbates the need for close control. There are a limited number of control actions available e.g. bicarbonate alkalinity (BA) dosing, temporary diversion of load by feed rate variation, or dilution with final effluent. Monitoring of conventional anaerobic digester systems typically consists of a combination of intermittent manual sampling followed by off-line analysis coupled with qualitative observations. Hence a decline in reactor performance could go unnoticed for a significant period of time. A simple yet reliable control system could not only minimise labour, but could also react to any changes in reactor conditions as soon as they occurred, leading to more efficient process operation, higher quality treatment and ultimately greater economic gain. The industrially recognised 'bottleneck' in the quest for automatic control is the availability of reliable and cheap on-line analysers. In the work presented here a series of experiments have been carried out on a simulated sugar processing wastewater using an on-line BA monitor in conjunction with an adaptive control strategy developed in a parallel PhD project. The possibility of achieving successful automatic control of an EGSB reactor through its start up phase and also during steady state operation (including some degree of process optimisation) and a series of organic step-change experiments was investigated. Two different control actions to maintain a BA set-point in the reactor, organic loading rate (OLR) variation and BA dosing, were compared. Research was carried out on a 30 1 EGSB reactor rig operating at 37 °C, fitted with on-line sensors to measure temperature, gas production, carbon dioxide percentage and pH. All sensors were interfaced with a PC configured to scan the sensors at one minute intervals. Five attempts to automatically start-up the EGSB reactor were made (Experiments 1-5), using OLR variation as a control action at a constant hydraulic retention time (HRT) of 23.3 hours, with various improvements and adjustments made to the reactor and control system after each. It was concluded that it was not possible to automatically control start-up to steady state using OLR as a control action using the BA monitor and controller in their present forms. Main reasons for this were the susceptibility of the laboratory-scale BA monitor to blockage by biomass washed out of the reactor (a common occurrence during the start-up phase) and the severity of loading rate oscillations. For Experiment 6 BA was dosed according to the relationship of the on-line BA monitor output to the BA setpoint, and OLR was changed approximately weekly according to operator expertise based on on- and off-line data and visual observations. HRT was maintained at 22 hours. A successful, sustainable startup was achieved, with mean % COD removal during the first 10 weeks being 78 % at a mean OLR of 9 kgCOD/m3 /day. After the successful start-up period, the reactor's HRT was approximately halved to 11.2 hours, and two OLR stepchange experiments (from 10.0 kgCOD/m 3/day to 28.1 kgCOD/m3 /day, and from 11.8 kgCOD/m3/day to 32.4 kgCOD/mVday) of twelve hour duration were carried out, followed by a removal of the control system and a similar organic step-change experiment (13.0 kgCOD/m 3/day to 32.9 kgCOD/m 3/day). It was found that approximately halving the HRT had no significant effect on the biomass or biomass activity. The HRT change did however adversely affect the smoothness of control, although control was not lost, as the on-line BA was always kept between 1500 and 2000 mgCaCO3/l. All parameters measured (pH, BA TVFA, effluent COD, carbon dioxide percentage, off-line methane percentage) indicated that conditions were less severe during and after organic step-changes when control was present. The controller also minimised the time spent at pH values potentially damaging to the bacteria (time spent at pH less than 6.0 in the two OLR step-change experiments where control was present (Experiments 6.3 and 6.4) was no greater than one hour, and in the experiment with no control (Experiment 6.5) was 8 hours) and returned the reactor to conditions conducive to efficient waste water treatment faster than when no control was present. Throughout all experiments controller oscillations remained severe. In this case, BA dosing as a control action was preferable, as the destructive effect of severe oscillations in the volume of BA dosed was considerably less than the effect of severe oscillations in the OLR, which repeatedly led to washout. Although it was possible to control the reactor subjected to OLR step-changes using the BA monitor based control system, control of the start-up phase was problematic. The BA monitor was not reliable or robust enough to provide the requisite data for use in the automatic control of the start-up of a high rate anaerobic digester. A thorough professional re-engineering of the B A monitor to deal with a greater sample flow rate, deliverable by a full-scale reactor (using wider bore tubing and larger flows, a more precise pumping system, and possibly with a suitable low maintenance sample filtration unit) could provide a suitably reliable and robust instrument.

Bacteroides fragilis strain Bf-1 produces an extracellular bacteriocin at the beginning of the stationary growth phase. Production is not inducible by either ultraviolet light or mitomycin C. The low molecular weight bacteriocin (MW estimates of 13 500 and 18 800 obtained from Sephadex G-100 chromatography and SDS-PAGE electrophoresis respecively) is stable between pH 7 - 9 and is inactivated on incubation with trypsin and pronase. An unusual feature of the Bf-1 bacteriocin is its apparent biphasic temperature stability: while the majority of the activity (97%) is destroyed by heating at 60ºC (t [subscript] 1/2 = 2.5 min at 60ºC), a small proportion (3%) is stable even after autoclaving at 121ºC for 15 min. The killing of sensitive cells occurs in 2 stages and the killing action is reversed by incubation with trypsin. The transition from stage I to stage II is dependent on the temperature of incubation and the growth state of sensitive cells. 2,4-Dinitrophenol prevents this transition. The Bf-1 bacteriocin has an unusual mode of action. It specifically inhibits RNA synthesis whilst having no effect on protein or DNA synthesis. No effect on intracellular ATP levels were observed. The heat-stable (3%) fraction had a similar biochemical effect. In vitro studies involving RNA polymerase indicated that the bacteriocin and the antibiotic rifampicin have similar effects on RNA synthesis. The bacteriocinogenic strain (Bf-1) is insensitive to its own bacteriocin both in vivo and in vitro, although this immunity is overcome in vitro by the addition of higher concentrations of the Bf-1 bacteriocin. The bacteriocinogenic strain (Bf-1) harbors a cryptic plasmid (or plasmids) which on a neutral sucrose gradient, sediments faster than the Col E1 marker plasmid DNA. Attempts to cure this strain of its bacteriocinogenic phenotype were unsuccessful.

A recently isolated freshwater methanogenium species, Methanogenium wolfei, is characterized. Cells were irregular cocci, measuring 1.5 to 2.0 micrometers in diameter. No motility was observed, but 1 to 2 flagella per cell were observed after staining with Gray's Flagella Stain. Colonies formed by this species were small, shiny, and green-brown in color. Formate or hydrogen plus carbon dioxide served as substrates for growth. The optimal temperature for growth was found to be 45 degrees centigrade with minimal growth below 30 degrees centigrade and above 55 degrees centigrade. The optimal pH for growth was determined to be 6.8. Optimal growth was obtained within a 0.0 to 0.2M range of added sodium chloride. Acetate and arginine were required for growth. DNA base composition was 61.1 mol%. G+C. The presence of coenzyme F-420 at a concentration of 134 mg/kg cells (wet weight) was determined in cell extracts. The enzyme NADP reductase was found to be present and was partially characterized.

No description available.

No description available.

An anaerobic, cellulose- decomposing bacteria was isolated in pure culture from the inghetata of a bovine rumen. The organism was a small, curved, Gram negative rod that occurred singly or in chains. The isolated bacterium was identified as a member of the genus Butyrivibrio because of its morphology and because of its production of certain volatile fatty acids in a rumen fluid-glucose medium fermentation. The characteristic fermentation waa the production of a large amount of butyric acid and 1ome lactic acid or succinic acid, and the lack of production of propionic acid. It was found that when rumen fluid was omitted from the fermentation medium the production of butyric acid decreased markedly. The organism was found to have a relatively narrow pH tolerance for the initiation of growth, pH 6.3 to 7.2, with an optimum of pH 6.9 to 7.0. Growth stopped at about pH 6.4, and continued fermentation decreased the pH to 6.0. The organism was cultured continuously on a medium which chemically defined except that vitamin-free casein hydrolysate was included, when the hydrolysate was replaced by a mixture of pure L-isomers of amino acids similar in composition to the hydrolysate, good growth occurred. However, when each amino acid was supplied at a uniform weight concentration, much weaker growth was obtained. Evidence was obtained indicating that amino acids were inhibitory, although the reason for the mild inhibition was not disclosed. The following amino acids were found to be critical nutrients, but in some cases their status, whether essential or stimulatory, was found to be dependent on the composition of the medium: - cysteine, histidine, isoleucine. methionine, lysine, tyrosine, asparagine and leucine. A medium containing only these amino acids supported only very weak growth. Aspartic acid was found to be mildly inhibitory to growth, and glutamic acid was found to reverse the inhibition. A mixture of the common purine and pyrimidine bases, and a mixture of volatile fatty acids, were each found to be inhibitory to growth. Biotin, folic acid, and pyridoxal were essential vitamins, but the other eight B-vitamins examined were found to be neither stimulatory nor essential. Carbon dioxide was found to be required in relatively high concentration in order for growth to start in a medium devoid of rumen fluid. Purines, pyrimidines, cobalamin, and Tween-80 in a mixture were found not to replace the carbon dioxide. Rumen fluid was found to contain material very stimulatory for growth of the Butyrivibrio. The stimulatory material was found to be possibly two compounds or types of compounds, one a peptide or peptide like substance, and the other an anionic substance which probably was polynucleotide-like. / Ph. D.

Strict anaerobic culture techniques were used to enumerate the anaerobic bacteria present in three soil sites located along a drainage catena near Blacksburg, Virginia. An anaerobic cooked meat plus 0.5% glucose medium cultured the largest number of anaerobes from the poorly drained soil. The population of obligate anaerobes ranged from 10⁶/ g dry weight soil on the poorly drained soil (% moisture = 112.06) to 10⁵/g dry weight soil on the intermediate soil (% moisture = 34.51) to 10⁴/g dry weight soil on the well drained soil (% moisture 20.81). The population of organisms able to grow anaerobically (facultative plus obligate) ranged from 10⁶/g dry weight soil on the poorly drained site to 10⁵/g dry weight soil on the well drained site. This same population on the poorly drained site was relatively constant over a nine month period with the exception of a sharp rise in early spring. The clostridia constituted at least one third of the obligately anaerobic bacteria present on the poorly drained soil. A sizeable percentage of the obligate anaerobic isolates on this site were either clostridia which formed spores unable to germinate in the medium employed, clostridia which were very pleomorphic in cell shape and gram reaction, or nonsporeforming obligate anaerobes. These results indicate that strict anaerobes and possibly nonsporeforming strict anaerobes exist in soils of different drainage character even though facultative organisms appear to be more successful competitors on the more well drained sites. / Master of Science

published_or_final_version / abstract / toc / Microbiology / Master / Master of Philosophy

Bibliography: leaves 189-205. / xi, 205 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this PhD project is to screen feral goat rumen fluid for the presence of new organisms that may play a role in the detoxification of tannins and to investigate their mechanisms of action. An enrichment experiment is conducted to screen rumen fluid for anaerobic bacteria capable of growing in the presence of high levels of "Acacia" condensed tannin. Four morphologically-distinct bacteria are isolated, confirming that resistance is a property shared by more than one organism. One isolate is chosen at random for further characterisation and is identified as a strain of "Selenomonas ruminantium" subspecies "ruminantium". It is arbitrarily designated strain K2. "Selenomonas ruminantium" K2 is shown to be not only tannin-resistant but also able to grow on tannic acid. It is proposed that this bacterium obtained energy for growth from tannic acid. The thesis examines the molecular mechanisms controlling tannin resistance or tannin degradation in rumen microorganisms. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1997

Bibliography: leaves 189-205. / xi, 205 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this PhD project is to screen feral goat rumen fluid for the presence of new organisms that may play a role in the detoxification of tannins and to investigate their mechanisms of action. An enrichment experiment is conducted to screen rumen fluid for anaerobic bacteria capable of growing in the presence of high levels of "Acacia" condensed tannin. Four morphologically-distinct bacteria are isolated, confirming that resistance is a property shared by more than one organism. One isolate is chosen at random for further characterisation and is identified as a strain of "Selenomonas ruminantium" subspecies "ruminantium". It is arbitrarily designated strain K2. "Selenomonas ruminantium" K2 is shown to be not only tannin-resistant but also able to grow on tannic acid. It is proposed that this bacterium obtained energy for growth from tannic acid. The thesis examines the molecular mechanisms controlling tannin resistance or tannin degradation in rumen microorganisms. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1997