Activation of proteases in an anaerobic sulphidogenic bioreactor
- Authors: Whiteley, Chris , Pletschke, Brett , Rose, Peter , Tshivhunge, Sylvia , Watson, Shaun , Whittington-Jones, Kevin
- Date: 2004
- Type: Text , Journal article
- Relation: Biotechnology Letters Vol. 26, no. 1 (2004), p. 55-59
- Full Text: false
- Reviewed:
- Description: Activities of proteases were stimulated by specific sulphur metabolites during the enhanced hydrolysis of complex polymeric organic carbon in an anaerobic sulphidogenic environment. While sulphate at 1000 mg l(-1) inhibited proteases by 50%, there was a 2.5-fold increase in activity of proteases by added sulphite and a 3.6-fold increase from added sulphide. Two hypothetical models are proposed. First the sulphur species, sulphite (HSO3-) and sulphide (HS-), liberated at different times during the sulphate reduction process, directly activate the proteases, which are associated with the organic particulate matter, leading to a subsequent enhancement of hydrolysis of polymeric material. Second, they indirectly activate the proteases by neutralising the cations on the floc surface disrupting the integrity of the organic particulate floc therebye releasing further entrapped enzymes from the organic particulate matter.
The Australian Bush Fly (Musca vetustissima) as a potential vector in the transmission of foodborne pathogens at outdoor eateries
- Authors: Vriesekoop, Frank , Shaw, Rachel
- Date: 2009
- Type: Text , Journal article
- Relation: Foodborne Pathogens and Disease Vol. 7, no. 3 (2009), p. 275-279
- Full Text: false
- Reviewed:
- Description: Abstract Australian outdoor activities are often accompanied by a barbeque (BBQ) with family, friends, and guests, which are often interrupted by uninvited guests in the form of the Australian bush fly, Musca vetustissima. We investigated the bacterial loading associated with the Australian bush in three different environments: on a cattle farm, in a typical urban area (shopping center car park), and at a BBQ. The highest bacterial populations per fly were found to occur in a farm environment (9.1×104 CFU per fly), whereas the bacterial population was lowest on flies caught in an urban environment (1.9×104 CFU per fly). The median CFU per fly caught near a BBQ was 5.0×104. Escherichia coli was the most commonly isolated potential pathogen, whereas Shigella sp. was the least common bacterial isolate that was screened. All isolated foodborne pathogens or indicator bacteria were screened for antibiotic resistance against commonly prescribed antibiotics. This revealed a very high prevalence of multidrug resistance, especially among the Salmonella and Shigella isolates of 94% and 87% resistance, respectively, against amoxicillin, roxythromycin and cefaclor.
Investigations into the thiamine and riboflavin content of malt and the effects of malting and roasting on their final content
- Authors: Hucker, Barry , Wakeling, Lara , Vriesekoop, Frank
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Cereal Science Vol.56, no.2 (2012), p.300-306
- Full Text: false
- Reviewed:
- Description: A simple and effective method for the analysis of thiamine (B1) and riboflavin (B2) vitamers, in unmalted and malted grains, by high performance liquid chromatography (HPLC) has been developed. This method makes use of trichloroacetic acid (TCA) as an extraction medium to effectively clean up the sample and analyze the vitamer content with high accuracy (R2 > 0.9992; %RSD < 5%). This method was employed in the routine analysis of a wide range of malted and unmalted grains, and it was found that lighter colored malts contain higher concentrations (2–5 times higher) of thiamine and riboflavin vitamers compared to darker colored malts. The malting process has no effect on the overall riboflavin content; however, both steeping and kilning processes cause increases in thiamine vitamer content. Roasting profiles show that thiamine and riboflavin vitamer concentrations are significantly effected when the temperature reaches 120 °C, which explains why roasted products have lower vitamer content than paler malts.
- Description: A simple and effective method for the analysis of thiamine (B
Vitamins in brewing : Effects of post-fermentation treatments and exposure and maturation on the thiamine and riboflavin vitamer content of beer
- Authors: Hucker, Barry , Vriesekoop, Frank , Vriesekoop-Beswick, Arielle , Wakeling, Lara , Vriesekoop-Besick, Hamish , Hucker, Amy
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of the Institute of Brewing Vol. 122, no. 2 (2016), p. 278-288
- Full Text: false
- Reviewed:
- Description: Post-fermentation processes and maturation are important steps in beer production as they help to shape the organoleptic properties and stabilize the final product. Brewers can use a variety of processing aids (e.g. isinglass, PVPP, etc.) and processes (e.g. pasteurization, bottle conditioning, etc.) to achieve a desired final product with a desirable shelf life; however, these processes can have detrimental effects on the vitamin content of the beer. This research found that heat treatments have a marked influence on the decrease in the thiamine diphosphate vitamer, while PVPP and silica treatments have a greater influence on the decrease in riboflavin vitamers. Refrigeration, filtration or centrifugation have no, or only very limited, influence on thiamine or riboflavin vitamers, while application of isinglass, bentonite, tannic acid and SO2 causes a decrease in both thiamine and riboflavin vitamers. Storage of beer at refrigerated temperatures appears to provide protection against significant degradation of both thiamine and riboflavin vitamers; however, storage of filtered beer at elevated temperatures shows a decrease in thiamine diphosphate and riboflavin. Storage of bottle-conditioned beer at elevated temperatures shows a marked decrease in yeast viability, accompanied by a decrease in thiamine diphosphate and free riboflavin, and a marked increase in free thiamine. These findings provide an insight into the reason why there is a significant variation in the vitamer content of beers, even within a single beer style. © 2016 The Institute of Brewing & Distilling.
The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer
- Authors: Hucker, Barry , Christophersen, Melinda , Vriesekoop, Frank
- Date: 2017
- Type: Text , Journal article
- Relation: Journal of the Institute of Brewing Vol. 123, no. 1 (2017), p. 24-30
- Full Text: false
- Reviewed:
- Description: Beer is generally considered a stable product owing to its intrinsic ‘unfavourable’ conditions (hops, alcohol, low oxygen, etc.) that inhibit the growth of pathogenic microorganisms. However spoilage microorganism such as Lactobacillus brevis, Pediococcus damnosus, Acetobacter aceti, Zymomonas mobilis and various wild yeasts (e.g. Brettanomcyes spp.) can have significant detrimental effects on the organoleptic properties of the final product. The presence of essential vitamins, such as thiamine and riboflavin, can help to enhance the growth of these microorganisms, accelerating the rate of spoilage. The presence of thiamine had a noticeable effect on the lactic acid productivity of L. brevis and P. damnosus, acetaldehyde productivity of Z. mobilis and acetic acid production of Brettanomyces spp., while riboflavin enhanced 2,3-pentanedione production by P. damnosus and Brettanomyces spp. Copyright © 2017 The Institute of Brewing & Distilling. Copyright © 2017 The Institute of Brewing & Distilling
Reverse engineering genetic networks using nonlinear saturation kinetics
- Authors: Youseph, Ahammed , Chetty, Madhu , Karmakar, Gour
- Date: 2019
- Type: Text , Journal article
- Relation: BioSystems Vol. 182, no. (2019), p. 30-41
- Full Text:
- Reviewed:
- Description: A gene regulatory network (GRN) represents a set of genes along with their regulatory interactions. Cellular behavior is driven by genetic level interactions. Dynamics of such systems show nonlinear saturation kinetics which can be best modeled by Michaelis-Menten (MM) and Hill equations. Although MM equation is being widely used for modeling biochemical processes, it has been applied rarely for reverse engineering GRNs. In this paper, we develop a complete framework for a novel model for GRN inference using MM kinetics. A set of coupled equations is first proposed for modeling GRNs. In the coupled model, Michaelis-Menten constant associated with regulation by a gene is made invariant irrespective of the gene being regulated. The parameter estimation of the proposed model is carried out using an evolutionary optimization method, namely, trigonometric differential evolution (TDE). Subsequently, the model is further improved and the regulations of different genes by a given gene are made distinct by allowing varying values of Michaelis-Menten constants for each regulation. Apart from making the model more relevant biologically, the improvement results in a decoupled GRN model with fast estimation of model parameters. Further, to enhance exploitation of the search, we propose a local search algorithm based on hill climbing heuristics. A novel mutation operation is also proposed to avoid population stagnation and premature convergence. Real life benchmark data sets generated in vivo are used for validating the proposed model. Further, we also analyze realistic in silico datasets generated using GeneNetweaver. The comparison of the performance of proposed model with other existing methods shows the potential of the proposed model.
Rainforest, woodland or swampland? Integrating time, space and culture to manage an endangered ecosystem complex in the Australian wet tropics
- Authors: Lynch, A. , Ferrier, Asa , Ford, A. J. , Haberle, Simon , Rule, Stephen , Schneider, Larissa , Zawadzki, A. , Metcalfe, Daniel
- Date: 2020
- Type: Text , Journal article
- Relation: Landscape Ecology Vol. 35, no. 1 (2020), p. 83-99
- Full Text: false
- Reviewed:
- Description: Context: Transdisciplinary research is important where information from multiple fields is required to develop ecologically and culturally appropriate environmental planning that protects local conservation and socio-cultural values. Objectives: Here, we describe research to inform ecosystem restoration and conservation of Chumbrumba Swamp within the Wet Tropics World Heritage Area, Australia. Many such open wetlands in the region have been degraded through agriculture and pastoral production, but there has been little research into their status, history and conservation needs. Methods: The recent to pre-European settlement history of the site was explored, along with spatial variation of vegetation communities at the site, and these data integrated with historical and ethnographical information on the site and its cultural values. Results: The botanical and palaeoecological analyses showed that Chumbrumba Swamp comprises a unique and highly sensitive ecosystem mosaic with high biodiversity. An endangered ecosystem complex, 82 vascular plant species, several disjunct or endemic taxa, and species at new northern range limits were recorded within its 20 ha area. The site comprises a stable swamp site with fringing woodland and rainforest that has persisted for around 5000 years. European settlement overlaid changes in the vegetation from disturbance (e.g. fire, clearing, grazing). However, fire also affected the swamp site during pre-European times. Conclusions: Historical and ethnographic information contextualised the biophysical data and confirmed the cultural importance of the site and the dynamic interactions between ‘people and nature’. These results have been used to inform environmental restoration and validate the importance of a transdisciplinary and precautionary approach to planning wetland restoration and conservation. © 2019, Springer Nature B.V.
River management and environmental water allocation in regulated ecosystems of arid and semi-arid regions – a review
- Authors: Atazadeh, Ehsan , Barton, Andrew , Shirinpour, Mozhgan , Zarghami, Mahdi , Rajabifard, Abbas
- Date: 2020
- Type: Text , Journal article
- Relation: Fundamental and Applied Limnology Vol. 193, no. 4 (2020), p. 327-345
- Full Text: false
- Reviewed:
- Description: Rivers make a significant contribution in providing goods and services for human well-being. Today, many rivers and streams have been heavily regulated to ensure adequate provision of water resources for anthropogenic uses. Riverine ecosystems, especially those in arid and semi-arid regions, are experiencing severe stress due to the increasing demands on the ecosystem services they provide, coupled with anthropogenic catchment-scale impacts and factors associated with natural and human-induced climate variability and change. In this paper, the various flow components in regulated riverine ecosystems and the methods to determine environmental flows are reviewed. The review also focuses on the concurrent developments of eco-hydrological models and on the new opportunities for improving environmental flows of rivers by sustainably adjusting consumptive flows to fine-tune environmental flows and maximize the ecological benefit. In fact, the present paper highlights the role of consumptive flows, towards improving environmental flows, which has largely been neglected by river scientists and water managers. Indeed, consumptive flows can provide an opportunity to improve and support environmental flows in regulated riverine ecosystems. Addressing these challenges may aid water management efforts in finding sustainable solutions in riverine ecosystems by balancing environmental/ecological and human water requirements. © 2020 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany.