Browsing by Author "Huddy, Robert J"

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    Characterisation of the Complex Microbial Community Associated with the ASTER™ Thiocyanate Biodegradation System
    (Elsevier, 2015-05-15) Huddy, Robert J; Van Zyl, A Wynand; Van Hille, Robert P; Harrison, Susan TL
    The ASTER™ process is used to bioremediate cyanide- (CN-) and thiocyanate- (SCN-) 13 containing waste water. This aerobic process is able to reduce the CN- and SCN14 concentrations to below 1 mg/L efficiently in a continuous system, facilitating reuse of 15 process water or safe discharge. Such remediation systems, which completely eliminate risk 16 associated with the pollutants, are essential for sustainable mineral processing and the long 17 term minimisation of environmental burden through both pollutant destruction and exploiting 18 opportunities for nutrient recycle. Process robustness of these bioremediation options can be 19 enhanced by good understanding of the microbial community involved in the process. To 20 date, the microbial consortia associated with the ASTER™ bioprocess have been poorly 21 characterised using isolation approaches only. As a result, the relative abundance and 22 diversity of the community has been significantly under-represented. In this study, both planktonic and biofilm-associated biomass have been observed. 23 Microscopy has revealed the 24 diversity of these communities, including bacteria, motile eukaryotes, filamentous fungi and 25 algae, with the biofilm densely packed with microorganisms. The results of the molecular 26 characterisation study reported here, using a clone library approach, demonstrate that the 27 microbial community associated with the ASTER™ bioprocess system is far more complex 28 than previously suggested, with over 30 bacterial species identified thus far. On-going 29 investigations focus on identification of key microbial community members associated with 30 SCN- biodegradation and other critical metabolic functions, as well as the expected dynamic 31 response of this complex microbial community to shifts in the operating window of the 32 process.
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    Detection and localisation of the abalone probiotic Vibrio midae SY9 and its extracellular protease, VmproA, within the digestive tract of the South African abalone, Haliotis midae
    (Public Library of Science, 2014) Huddy, Robert J; Coyne, Vernon E
    Probiotics have been widely reported to increase the growth rate of commercially important fish and shellfish by enhancing the digestion of ingested feed through the production of extracellular enzymes such as proteases and alginases. In order to investigate this further, the objective of this study was to localise the bacterial probiont Vibrio midae SY9 and one of the extracellular proteases it produces in the digestive tract of the South African abalone Haliotis midae. This was accomplished by inserting a promotorless gfp gene into the chromosome of the bacterium which was incorporated in an artificial, fishmeal-based abalone feed. In situ histological comparison of abalone fed either a basal diet or the basal diet supplemented with V. midae SY9::Tn10.52 using a cocktail of DNA probes to the gfp gene localised the probiont to the crop/stomach and intestinal regions of the H. midae digestive tract. Generally, the ingested probiotic bacterium occurred in association with feed and particulate matter within the crop/stomach and intestinal regions, as well as adhered to the wall of the crop/stomach. Histological immunohistochemical examination using polyclonal anti-VmproA antibodies localised an extracellular protease produced by V. midae SY9 to the H. midae crop/stomach and intestine where it appeared to be associated with feed and/or other particulate matter in the abalone gut. Thus the data suggests that V. midae SY9 colonises and/or adheres to the mucous lining of the abalone gut. Furthermore, the close association observed between the bacterium, its extracellular protease and ingested feed particles supports the theory that V. midae SY9 elevates in situ digestive enzyme levels and thus enhances feed digestion in farmed abalone.