Richard Bentham
Flinders University
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Publication
Featured researches published by Richard Bentham.
Microbial Ecology | 2009
Michael Taylor; Kirstin Ross; Richard Bentham
Currently, the investigation of Legionella ecology falls into two distinct areas of research activity: (1) that Legionella multiply within water sources by parasitizing amoebic or ciliate hosts or (2) that Legionella grows extracellularly within biofilms. Less focus has been given to the overlaps that may occur between these two areas or the likelihood that Legionella employs multiple survival strategies to persist in water sources. It is likely that Legionella interacts with protozoa, bacteria, algae, fungi, etc., and biofilm components in a more complex fashion than multiplication or death due to the presence or absence of single components of these complex microbial systems. This paper addresses gaps that exist in the understanding of Legionella ecology and serves to pinpoint areas of future research. To assume that only one other class of organism is important to Legionella ecology may limit our understanding of how this bacterium proliferates in heated water sources and also limit our strategies for its control in the built environment.
Emerging Infectious Diseases | 2011
Harriet Whiley; Richard Bentham
Reported cases of legionellosis attributable to Legionella longbeachae infection have increased worldwide. In Australia and New Zealand, L. longbeachae has been a known cause of legionellosis since the late 1980s. All cases for which a source was confirmed were associated with potting mixes and composts. Unlike the situation with other Legionella spp., L. longbeachae–contaminated water systems in the built environment that cause disease have not been reported. Spatially and temporally linked outbreaks of legionellosis associated with this organism also have not been reported. Sporadic cases of disease seem to be limited to persons who have had direct contact with potting soil or compost. Long-distance travel of the organism resulting in infection has not been reported. These factors indicate emergence of an agent of legionellosis that differs in etiology from other species and possibly in route of disease transmission.
International Journal of Environmental Research and Public Health | 2013
Harriet Whiley; Ben van den Akker; Steven Giglio; Richard Bentham
Campylobacteriosis is infection caused by the bacteria Campylobacter spp. and is considered a major public health concern. Campylobacter spp. have been identified as one of the most common causative agents of bacterial gastroenteritis. They are typically considered a foodborne pathogen and have been shown to colonise the intestinal mucosa of all food-producing animals. Much emphasis has been placed on controlling the foodborne pathway of exposure, particularly within the poultry industry, however, other environmental sources have been identified as important contributors to human infection. This paper aims to review the current literature on the sources of human exposure to Campylobacter spp. and will cover contaminated poultry, red meat, unpasteurised milk, unwashed fruit and vegetables, compost, wild bird faeces, sewage, surface water, ground water and drinking water. A comparison of current Campylobacter spp. identification methods from environmental samples is also presented. The review of literature suggests that there are multiple and diverse sources for Campylobacter infection. Many environmental sources result in direct human exposure but also in contamination of the food processing industry. This review provides useful information for risk assessment.
Science of The Total Environment | 2010
Sharyn Gaskin; Richard Bentham
Rhizoremediation involves the breakdown of contaminants in soil resulting from microbial activity that is enhanced in the plant root zone. The objective of this study was to assess Australian native grasses for their ability to stimulate removal of aliphatic hydrocarbons from a mine site soil. Time-course pot experiments were conducted in a greenhouse with three grass species (Cymbopogon ambiguus, Brachiaria decumbens, and Microlaena stipoides) in a mine site soil experimentally contaminated with a 60:40 diesel:oil mixture at 1% (w/w) concentration. Plants were cultivated for 100days with periodic evaluation of changes in soil total petroleum hydrocarbon (TPH) concentration, soil lipase activity, and abundance of hydrocarbon-degrading microorganisms. Results were compared to unplanted control treatments. Significantly lower endpoint TPH concentrations were recorded in planted soil compared to unplanted soil (p=0.01). Final TPH concentrations and rates of TPH removal varied between grass species, with total TPH removal of between 50% and 88% achieved in planted treatments. The presence of grasses significantly increased the abundance of hydrocarbon-degrading microorganisms and soil lipase activity relative to unplanted soil (p<0.05). Residual TPH concentration was found to be closely (negatively) correlated with abundance of hydrocarbon-degrading microorganisms and to a lesser extent with soil lipase activity. Australian native grass species were identified that effectively enhance the remediation of diesel/oil contaminated soil, without any requirement for nutrient supplementation. Results may have extensive application to the nationwide problems associated with hydrocarbon contaminated sites.
Applied Microbiology and Biotechnology | 2006
Benjamin Dearman; Petra Marschner; Richard Bentham
Anaerobic co-digestion of food waste and biosolids was carried out in sequential batch and single-stage batch systems in four treatments. Methane yield, which was used as a functional process parameter, differed between treatments, with the single-stage batch system generating lower volumes than the sequential batch systems. Volatile fatty acid (VFA) concentrations and pH in the leachate also differed between treatments. VFA concentrations were highest and methane generation yields lowest in the single-stage batch system in comparison to the sequential batch systems. The anaerobic microbial community structure of the domains Archaea and Bacteria, determined by denaturing gradient gel electrophoresis, differed between treatments and was correlated to a number of environmental parameters such as pH, VFA concentration and methane generation rate. Methane generation rate was significantly correlated to the community structure of Bacteria but not Archaea. This indicated that the substrates that are produced by acetogens (Bacteria) are important for the growth and community structure of the methanogens (Archaea). Community structure of Archaea changed over time, but this had no observable effect on functional ability based on methane yields. Microbial diversity (H′) was shown to be not important in developing a functionally successful anaerobic microbial community.
Current Microbiology | 2000
Richard Bentham
Cooling water samples from 31 cooling tower systems were cultured for Legionella over a 16-week summer period. The selected systems were known to be colonized by Legionella. Mean Legionella counts and standard deviations were calculated and time series correlograms prepared for each system. The standard deviations of Legionella counts in all the systems were very large, indicating great variability in the systems over the time period. Time series analyses demonstrated that in the majority of cases there was no significant relationship between the Legionella counts in the cooling tower at time of collection and the culture result once it was available. In the majority of systems (25/28), culture results from Legionella samples taken from the same systems 2 weeks apart were not statistically related. The data suggest that determinations of health risks from cooling towers cannot be reliably based upon single or infrequent Legionella tests.
Journal of Applied Microbiology | 2004
C.E. Dandie; S.M. Thomas; Richard Bentham; N.C. McClure
Aim: The aim of this study was to further characterize a bacterial culture (VUN 10,010) capable of benzo[a]pyrene cometabolism.
Journal of Applied Microbiology | 2012
Harriet Whiley; Alexandra Keegan; Steven Giglio; Richard Bentham
Mycobacterium avium complex (MAC) is a group of opportunistic pathogens of major public health concern. It is responsible for a wide spectrum of disease dependent on subspecies, route of infection and patients pre‐existing conditions. Presently, there is limited research on the incidence of MAC infection that considers both pulmonary and other clinical manifestations. MAC has been isolated from various terrestrial and aquatic environments including natural waters, engineered water systems and soils. Identifying the specific environmental sources responsible for human infection is essential in minimizing disease prevalence. This paper reviews current literature and case studies regarding the wide spectrum of disease caused by MAC and the role of potable water in disease transmission. Potable water was recognized as a putative pathway for MAC infection. Contaminated potable water sources associated with human infection included warm water distribution systems, showers, faucets, household drinking water, swimming pools and hot tub spas. MAC can maintain long‐term contamination of potable water sources through its high resistance to disinfectants, association with biofilms and intracellular parasitism of free‐living protozoa. Further research is required to investigate the efficiency of water treatment processes against MAC and into construction and maintenance of warm water distribution systems and the role they play in MAC proliferation.
International Journal of Phytoremediation | 2008
Sharyn Gaskin; Kathleen L. Soole; Richard Bentham
Rhizoremediation involves the breakdown of contaminants in soil resulting from microbial activity that is enhanced in the plant root zone. The objective of this study was to identify Australian native grass species as suitable candidates for rhizoremediation application. Seeds of nine perennial Australian native grasses were sown in soil from a mine site and artificially contaminated with a 60:40 diesel/oil mixture at concentrations of 1% (w/w), 0.5% (w/w), and 0% (control). Seedling emergence was not adversely affected by the presence of hydrocarbon contamination for all but one grass species. Three promising species (Brachiaria decumbens, Cymbopogon ambiguus, and Microlaena stipoides var. Griffin) were assessed for growth characterization in contaminated and uncontaminated soils. The evaluated species survived for 120 days in the contaminated soil and, in some instances, produced considerably more root biomass in the presence of contamination. C. ambiguus showed growth stimulation in the presence of contamination (1% and 0.5% w/w) with significantly increased root biomass production compared with the control (p = 0.0001). B. decumbens and M. stipoides showed tolerance, without adverse growth effects in the presence of diesel/oil at the exposed concentrations. Stimulation of the rhizosphere microbial population that is capable of degrading diesel/oil was found for all of the species tested, using a most probable number method for enumeration. This investigation has identified suitable candidates for further investigation of their rhizoremediation potential.
Journal of Applied Microbiology | 2009
Michelle Critchley; Richard Bentham
Aims: In vitro experiments were undertaken to evaluate biocide formulations commonly used in cooling water systems against protozoa previously isolated from cooling towers. The investigations evaluated the efficacy of these formulations against amoebic cysts and trophozoites.
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Commonwealth Scientific and Industrial Research Organisation
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