Geoffrey Hamer

Cryptic growth in Klebsiella pneumoniae

SummaryThe ability of Klebsiella pneumoniae to grow on its own soluble lysis products is shown in a series of batch growth experiments. Maximum specific growth rate coefficients ranging from 0.69 to 1.46 h-1 were obtained with experimental “cryptic” yield coefficients ranging between 0.42 to 0.52 (mg-cell-C/mg-substrate-C). These kinetic data are used to calibrate a model which demonstrates that depression of theoretical maximum yield coefficients relative to experimentally obtained values can be explained by “cryptic” growth phenomena without the need to resort to the use of physiologically undefined, mathematical constants. Growth of K. pneumoniae on sonicated cells derived from steady-state chemostat cultures was followed in batch culture and observed to occur with no lag phase. Batch growth curves did not indicate either diauxic or polyauxic growth, suggesting simultaneous utilization of the complex organic substrate mixture. These data suggest that “cryptic” growth is probably a real event occurring in growing chemostat cultures under ideal growth conditions and most probably also under starvation conditions.

Thermotolerant and Thermophilic Solvent-Utilizing Methylotrophic, Aerobic Bacteria

Summary Eight strains of obligately aerobic thermophilic bacteria able to utilize methanol as the sole source of carbon and energy for growth in synthetic media were obtained by enrichment from samples derived from an aerobic thermophilic waste sludge treatment process operating at 60°–65°C. Seven of these isolates were aerobic, endosporeforming Bacillus brevis strains. The other strain was a sheathed filamentous Gram-positive endosporeforming obligately aerobic bacterium. Its affiliation to any presently described genus or species was not possible. Its similarities with other filamentous bacteria are discussed.

Aerobic thermophilic biodegradation of microbial cells

SummaryResults are presented comparing the extent of solubilization/biodegradation of whole yeast cells by mixed thermophilic bacterial cultures under conditions of oxygen, excess and oxygen limitation. The process was most effective at a low dissolved oxygen concentration as suggested by solids removal data and by the production of often considerable quantities of carboxylic acids. The temperature optimum was also investigated and, under oxygen limited conditions, the most consistant results were obtained for operation at 65°C reflecting the true thermophilic nature of the process microbes. An operating temperature of 70°C probably exceeded the optimum for effective functioning of the thermophilic microbes and resulted in a less efficient process, whilst an operating temperature of 60°C was intermediate with respect to its effectiveness.

Determination of nitrilotriacetate in biological matrices using ion exclusion chromatography

A sensitive method for the determination of nitrilotriacetate in biological growth media and cell-free extracts by ion exclusion chromatography is described using HCl as an eluant. The eluant conductivity was chemically suppressed with a membrane suppressor and a conductivity detector was used for subsequent detection. The membrane was continuously regenerated with a tetrabutylammoniumhydroxide solution. The detection limit for nitrilotriacetate in cell-free extract was 11 mg/liter, while for nitrilotriacetate in growth media it was 1 mg/liter. Interference by compounds present in biological matrices with the determination is discussed.

The biooxidation of methanol, ethanol and isopropanol by a defined co-culture at elevated temperatures

The introduction of more imaginative enrichment and isolation procedures has permitted the isolation of pure cultures of thermotolerant methylotrophic bacteria, a group that was previously unknown. One potential application for such bacteria is in the aerobic biotreatment of petrochemical industry wastewaters at elevated temperatures. Here, the growth and biooxidation characteristics of one such bacterium, Bacillus sp. NCIB 12522, in co-culture with a Gram-negative thermophilic non-methylotrophic solvent utilizing bacterium, NA 17, on a mixture of methanol, ethanol and isopropanol, under both steady and transient state continuous flow culture conditions are reported. The results indicate that at dilution rates <0.2 h−1 effective biooxidation can be achieved at temperatures between 50° and 57 °C. As a result of step increases in bioreactor feed concentrations, the fraction of the methylotroph present in the co-culture changed according to whether the methanol or the ethanol concentrations were increased, but when isopropanol was increased, no change in the methylotroph fraction occurred between the initial and final steady states.

Polluted Heterogeneous Environments: Macro-scale Fluxes, Micro-scale Mechanisms, and Molecular Scale Control

Most large-scale processing ventures are initiated by ill-defined statements of need rather than by the discovery of either a new product or a novel process route. One of the best examples that has been contrary to this general pattern during the past decade has been the dramatic development of biotechnology, where one has seen both products and processes emerging as a result of research push rather than market pull. In contrast to this, environmental biotechnology is developing in response to a perceived need; the clean-up of indiscriminate pollution that has occurred from the advent of the industrial revolution until relatively recent times. With increasing public awareness and sensitivity to the crises that either have or will develop with respect to enviromental safety, health and quality, it is only now that politico-economic policies are being implemented that allow the development of technological responses to such crises. Newly evolving bioremediation and biorestoration technologies for soil and ground water clean-up, respectively, represent only one response scenario. Their future will depend on both their efficacy and their economics. Unless they continue to offer clear advantages on both counts, they will rapidly become obsolete. The maintenance of their relative attractiveness depends on the effectiveness and availability of underpinning fundamental research and its exploitation in solving practical problems.

Fluctuating environmental conditions in scaled-up bioreactors : heating and cooling effects

In biotechnology, as in most other process technologies, the design of and operating procedures for commercialand technical-scale plants are based on the scaleup of process research and process development data generated in laboratory-scale and pilot plant-scale equipment, respectively. The traditional approach to scaleup involves the establishment of relationships between systems of different sizes according to the principles of similarity. Spatial and temporal configurations in systems of different sizes are determined by ratios of specific magnitudes within the systems and are independent of system size. The process environment in all bioreactors comprises multiple phases that are subject to energy and mass transfer and complex, simultaneous reactions. When the concept of similarity is applied in the scaleup of bioreactors, it involves not only geometrical proportions, but, additionally, features such as fluid-flow patterns, temperature gradients, time-concentration profiles, etc. Similarity can be defined either by intrinsic proportions or by scale ratios, but, as far as bioreactors are concerned, similarity with respect to important variables such as velocity, force, or temperature is defined by an intrinsic ratio for the variable in question, that is, the appropriate dimensionless group. The three types of similarity that are important in bioreactor scaleup are

Some effects of heat shocks on bacterial growth

SummaryIn large industrial scale bioreactors process cultures are frequently exposed to supperoptimal temperatures for short intervals of time. Data concerning the physiologica effects of such exposures are scant. Here, experiments involving short term heat shocks on two bacteria, Klebsiella pneumoniae, a non-fastidious mesophile growing on glucose and Bacillus sp. NCIB 12522, a fastidious thermotolerant methylotroph growing on methanol, are described. Markedly different response patterns for the two bacteria are evident, clearly indicating not only the dangers of making generalizations with respect to the effects of superoptimal temperatures on growing bacterial cultures but also, the significance of scale related segregation phenomena such as wall growth.

Impacts of economic strategies on biotechnological developments

Abstract The traditional basis of the processing technologies is profit generation from the transformation of either raw materials or intermediates, using know-how and energy, into marketable products. However, the establishment of both regional economic communities and raw material producer cartels has distorted and even invalidated the economic evaluation of processes in strict economic terms. Essentially, individual countries and regions are moving towards a state of economic protectionism based on specific strategic policies. Such policies are most evident and effective in the agricultural and energy sectors. Biotechnology is intimately linked with both these sectors and major biotechnological ventures have failed as a result of strategic economic changes. This paper examines the basis for the economic evaluation of novel biotechnological processes and seeks to identify politico-economic scenarios that will permit successful establishment of biotechnological processing ventures.

Polluted water renovation for reuse: Recent biotechnological advances applicable in hot arid regions

Abstract Both sewage and industrial wastewater are important resources in hot arid regions provided they can be economically purified to meet the requirements of reuse. Conventional treatment technology involves a sequence of physical, biological and physico-chemical process steps designed for effective pollutant removal in temperate climates where, even there, overall process performance is rarely optimal. Frequently, the reason for this is that the process microbiology involved in biotreatment is little understood and very largely ignored in spite of the fact that it is the biotreatment step that is responsible for the removal of the bulk pollutant load. This contribution will consider recent advances in process microbiology that will permit more effective biotreater operation at high ambient temperatures and the way in which these advances can be incorporated in the design of biotreatment processses for the effective and economic purification of sewage and industrial wastewater, so as to allow their sensible reuse, and of waste sludge, so as to allow safe disposal on cultivated land. Emphasis will be placed particularly on noxious chemical pollutant and pathogenic organism elimination during biotreatment.