33 research outputs found
Comparison of growth and biofilm attachment of two microcystin-degrading bacteria to plasma polymerized surface coatings
No full textAbstract not availableLionel Ho, Christian Schwarz, Daniel Hoefel and David A. Steel
Comparison of drinking water treatment process streams for optimal bacteriological water quality
No full textAbstract not availableLionel Ho, Kalan Braun, Rolando Fabris, Daniel Hoefel, Jim Morran, Paul Monis, Mary Drika
Assessing the fate and biodegradation of cyanobacterial metabolites in Australian waters
No full textWith the exception of the saxitoxins, the cyanobacterial metabolites studied were shown to be biodegradable in two South Australian waters with the rate of biodegradation of the metabolites influenced by temperature and to a lesser extent, seasonal variations. The order of ease of biodegradability followed the trend: microcystin-LR > cylindrospermopsin > geosmin > 2-methylisoborneol > saxitoxins. Pseudo-first-order rate constants for the biodegradation of the metabolites ranged from 9.6 × 10−4 to 2.6 × 10−2 h−1.Tim Tang, Daniel Hoefel, Thorsten Mosisch and Lionel H
FACS enrichment and identification of floc-associated alphaproteobacterial tetrad-forming organisms in an activated sludge community
No full textA precise phylogenetic identity of the Defluviicoccus-related glycogen-accumulating organisms (GAO) observed after FISH probing in a novel activated sludge process removing phosphorus was sought with the aim of exploring the phylogenetic diversity of this important group. These organisms, whose sequences were not revealed in previously generated community wide 16S rRNA gene clone libraries, were identified using flow cytometry cell sorting of FISH-positive cells. Sequencing of a 16S rRNA gene clone library created from this sorted population identified the Defluviicoccus-related GAO as being highly related to previous identified GAO from enhanced biological phosphorus removal systems, despite a marked environmental difference between the two systems.Simon McIlroy, Daniel Hoefel, Sarah Schroeder, Johwan Ahn, Daniel Tillett, Christopher Saint & Robert J. Seviou
Biological filtration for the removal of chemical contaminants from re-use water
No full textThis paper presents findings from the application of biological sand filtration for the removal of a suite of chemical contaminants that can be found in re-use water. The contaminants of interest include a pesticide, endocrine disrupting chemicals, disinfection by-products and a cyanobacterial toxin. Results indicated that biological filtration can be effective for some of these contaminants, in particular, estrone and microcystin-LR. In contrast, atrazine, three nitrosamines and 17α-ethynylestradiol were not well removed. Molecular techniques were applied to detect genes involved in the degradation of specific contaminants, and some of these genes were detected within the biofilm of the sand filter.Lionel Ho, Nawal Kayal, Daniel Hoefel, Sebastian Palazot, Gayle Newcombe, Kylie Hyde, Chris Saint and Justin Brookeshttp://trove.nla.gov.au/work/37052193?versionId=4812708
Determination of rate constants and half-lives for the simultaneous biodegradation of several cyanobacterial metabolites in Australian source waters
No full textThe fate of five cyanobacterial metabolites was assessed in water sourced from Lake Burragorang (Warragamba Dam) in New South Wales, Australia. All of the studied metabolites were shown to be biodegradable in this water source. For some metabolites, biodegradation was influenced by factors, including temperature, location (within the water body) and seasonal variations. The biodegradation of the metabolites was shown to follow pseudo-first-order kinetics with rate constants ranging from 8.0 × 10(-4) to 1.3 × 10(-2) h(-1). Half-lives of the metabolites were also estimated and ranged from 2.2 to 36.1 d. The order of ease of biodegradability in this water source followed the trend: microcystin-LR ≥ cylindrospermopsin > saxitoxins > geosmin ≥ 2-methylisoborneol. The lack of detection of the mlrA gene during microcystin biodegradation suggests that these toxins may be degraded via a different pathway. While no metabolite-degrading organisms were isolated in this study, the inoculation of previously isolated geosmin- and microcystin-degrading bacteria into Lake Burragorang water resulted in efficient biodegradation of the respective metabolites. For example, microcystin-degrading isolate TT25 was able to degrade three microcystin variants to concentrations below analytical detection within 24 h, suggesting that inoculation of such bacteria has the potential to enhance biodegradation in Lake Burragorang.Lionel Ho, Tim Tang, Daniel Hoefel, Bala Vigneswara
Assessing the impact of the biological control agent Bacillus thuringiensis on the indigenous microbial community within the pepper plant phyllosphere
No full textCopyright © 2008 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.Although biological control agents (BCAs) have been used extensively for controlling insects and pathogens of plants, little is known regarding the effects of such agents on the indigenous microbial communities within the plant phyllosphere. We assessed the effect of the BCA Bacillus thuringiensis (Bt) on the microbial communities within the pepper plant phyllosphere using culture-independent methodologies. Phospholipid fatty acid (PLFA) analysis suggested that the bacterial and fungal biomass were not significantly affected following Bt application. However, principal component analysis of PLFA data indicated that Bt did change the phyllosphere microbial community structure significantly. 16S rRNA gene-directed PCR with denaturing gradient gel electrophoresis (DGGE) also suggested a significant change in the phyllosphere bacterial community structure following Bt inoculation. Phylogenetic analysis of excised DGGE bands suggested a change in bacterial phyla; bands from untreated samples predominantly belonged to the Firmicutes, while Gammaproteobacteria abounded in the treated samples.Baoguo Zhang, Zhihui Bai, Daniel Hoefel, Ling Tang, Zhiguang Yang, Guoqiang Zhuang, Jianzhou Yang & Hongxun Zhan
Removal of cyanobacterial metabolites through wastewater treatment plant filters
No full textWastewaters have the potential to proliferate excessive numbers of cyanobacteria due to high nutrient levels. This could translate to the production of metabolites, such as the saxitoxins, geosmin and 2-methylisoborneol (MIB), which can impair the quality of wastewater destined for re-use. Biological sand filtration was assessed for its ability to remove these metabolites from a wastewater. Results indicated that the sand filter was incapable of effectively removing the saxitoxins and in some instances, the effluent of the sand filter displayed greater toxicity than the influent. Conversely, the sand filter was able to effectively remove geosmin and MIB, with removal attributed to biodegradation. Granular activated carbon was employed as an alternative filter medium to remove the saxitoxins. Results showed similar removals to previous drinking water studies, where efficient removals were initially observed, followed by a decrease in the removal; a consequence of the presence of competing organics which reduced adsorption of the saxitoxins.Lionel Ho, Daniel Hoefel, Charlotte Grasset, Sebastien Palazot, Gayle Newcombe, Christopher P. Saint and Justin D. Brooke
Effects of cotton straw amendment on soil fertility and microbial communities
No full textMaintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven to be good soil amendments for increasing soil organic matter (OM) and a range of additional soil nutrients. However, little is known about the utilization of cotton straw for soil amendment. To better understand the mechanism behind cotton straw soil amendments, investigations were performed upon cucumber seedlings, where changes to soil nutrients and microbial communities were investigated. The results revealed that the cotton straw application promoted the cucumber seedling growth by significantly increasing the soil OM, available nitrogen, available phosphorus, and available potassium. The concentration of cotton straw was positively correlated to both the number of the culturable microorganisms and also the total microbial biomass within soil. Furthermore, assessment of cotton straw application using Biolog metabolic profiling and phospholipid fatty acid analysis revealed that such application increased the microbial community metabolic activity, and markedly changed the structure of microbial community. 16S rRNA gene clone library construction and phylogenetic analysis of soil bacteria revealed γ-Proteobacteria sequences dominated the cotton straw amendment soil, comprising 27.8% of the total number of analyzed sequences, while they were less represented in control soil (13.4%). On the contrary, the Sphingobacteria (7.8%) and Verrucomicrobia (2.4%) in the cotton straw amendment soil decreased after application when compared to the control soil 15.2% and 15.2%.Wuren Huang, Zhihui Bai, Daniel Hoefel, Qing Hu, Xin Lv, Guoqiang Zhuang, Shengjun Xu, Hongyan Qi and Hongxun Zhan
Biodegradation of di-n-butyl phthalate by an isolated Gordonia sp strain QH-11: Genetic identification and degradation kinetics
No full textDi-n-butyl phthalate (DBP) is one of the most widely used phthalic acid esters (PAEs), which have shown increasing environmental concerns worldwide. A bacterial strain designated as QH-11, was isolated from activated sludge and found to be capable of utilizing DBP as carbon and energy sources for growth. 16S rRNA and gyrb gene sequence analysis revealed that strain QH-11 was most closely related to Gordonia sp. Kinetics studies of DBP degradation by the strain QH-11 revealed that DBP depletion curves fit with the modified Gompertz model (R(2)>0.98). Meanwhile, substrate utilization tests showed that strain QH-11 could utilize other common PAEs and also the main intermediate product phthalic acid (PA). A gene encoding the large subunit of the phthalate dioxygenase, which is responsible for PA degradation, was successfully detected in strain QH-11. Furthermore, the results of reverse transcription quantitative PCR demonstrate that mRNA expression level of phthalate dioxygenase increased significantly after strain QH-11 was induced by DBP and PA.Decai Jin, Zhihui Bai, Dongdong Chang, Daniel Hoefel, Bo Jin, Ping Wang, Dongbin Wei, Guoqiang Zhuan
