Showing papers by "Andrew S. Ball published in 2020"

The Nutritional and Pharmacological Potential of New Australian Thraustochytrids Isolated from Mangrove Sediments.

Abstract: Mangrove sediments represent unique microbial ecosystems that act as a buffer zone, biogeochemically recycling marine waste into nutrient-rich depositions for marine and terrestrial species. Marine unicellular protists, thraustochytrids, colonizing mangrove sediments have received attention due to their ability to produce large amounts of long-chain ω3-polyunsaturated fatty acids. This paper represents a comprehensive study of two new thraustochytrids for their production of valuable biomolecules in biomass, de-oiled cakes, supernatants, extracellular polysaccharide matrixes, and recovered oil bodies. Extracted lipids (up to 40% of DW) rich in polyunsaturated fatty acids (up to 80% of total fatty acids) were mainly represented by docosahexaenoic acid (75% of polyunsaturated fatty acids). Cells also showed accumulation of squalene (up to 13 mg/g DW) and carotenoids (up to 72 µg/g DW represented by astaxanthin, canthaxanthin, echinenone, and β-carotene). Both strains showed a high concentration of protein in biomass (29% DW) and supernatants (2.7 g/L) as part of extracellular polysaccharide matrixes. Alkalinization of collected biomass represents a new and easy way to recover lipid-rich oil bodies in the form of an aqueous emulsion. The ability to produce added-value molecules makes thraustochytrids an important alternative to microalgae and plants dominating in the food, pharmacological, nutraceutical, and cosmetics industries.

Impact of necrophytoremediation on petroleum hydrocarbon degradation, ecotoxicity and soil bacterial community composition in diesel-contaminated soil.

Abstract: Hydrocarbon degradation is usually measured in laboratories under controlled conditions to establish the likely efficacy of a bioremediation process in the field. The present study used greenhouse-based bioremediation to investigate the effects of natural attenuation (NA) and necrophytoremediation (addition of pea straw (PS)) on hydrocarbon degradation, toxicity and the associated bacterial community structure and composition in diesel-contaminated soil. A significant reduction in total petroleum hydrocarbon (TPH) concentration was detected in both treatments; however, PS-treated soil showed more rapid degradation (87%) after 5 months together with a significant reduction in soil toxicity (EC50 = 91 mg diesel/kg). Quantitative PCR analysis revealed an increase in the number of 16S rRNA and alkB genes in the PS-amended soil. Substantial shifts in soil bacterial community were observed during the bioremediation, including an increased abundance of numerous hydrocarbon-degrading bacteria. The bacterial community shifted from dominance by Alphaproteobacteria and Gammaproteobacteria in the original soil to Actinobacteria during bioremediation. The dominance of two genera of bacteria, Sphingobacteria and Betaproteobacteria, in both NA- and PS-treated soil demonstrated changes occurring within the soil bacterial community through the incubation period. Additionally, pea straw itself was found to harbour a diverse hydrocarbonoclastic community including Luteimonas, Achromobacter, Sphingomonas, Rhodococcus and Microbacterium. At the end of the experiment, PS-amended soil exhibited reduced ecotoxicity and increased bacterial diversity as compared with the NA-treated soil. These findings suggest the rapid growth of species stimulated by the bioremediation treatment and strong selection for bacteria capable of degrading petroleum hydrocarbons during necrophytoremediation.

Factors Influencing the Concentration of Fecal Coliforms in Oysters in the River Blackwater Estuary, UK

Abstract: Contamination of water systems can not only entail high risks to human health but can also result in economic losses due to closure of beaches and shellfish harvesting areas. Understanding the origin of fecal pollution at locations where shellfish are grown is essential in assessing associated health risks—as well as the determining actions necessary to remedy the problem. The aim of this work is to identify the species-specific source(s) of fecal contamination impacting waters overlying the shellfisheries in the Blackwater Estuary, East Anglia, UK. Over a twelve-month period, water samples were taken from above the oysters and from a variety of upstream points considered to be likely sources of fecal microorganism, together with oyster samples, and the number of fecal streptococci and E. coli were determined. Transition from low to high tide significantly decreased the concentration of fecal streptococci in waters overlying the oyster beds, indicative of a freshwater input of fecal pollution in oyster bed waters. In 12 months, the number of E. coli remained constant throughout, while fecal streptococci numbers were generally higher in the winter months. Analyses of upstream samples identified a sewage outfall to be the main source of E. coli to the oyster beds, with additional fecal streptococci from agricultural sources. The findings may assist in developing approaches for assessing the risks to shellfishery industries of various fecal inputs into an estuary, which could then help local governmental authorities address the problem.

Real-time detection and identification of nematode eggs genus and species through optical imaging.

Abstract: Nematode eggs are pervasive pathogens that infect billions of people and livestock every year. Adult parasitic nematode worms can be distinguished based on their size and morphology. However, their eggs, particularly their species Ascaris lumbricoides and Ascaris suum cannot be identified from each other. Identifying eggs of helminths from wastewater and sludge is important from a public health perspective to minimize the spread of Ascaris infections. Numerous methods exist for nematode identification, from a morphological-based approach to high throughput sequencing technology. However, these techniques are not consistent and often laborious and time-consuming. In this study, we demonstrate that non-invasive real-time identification of eggs is possible based on their intrinsic fluorescence. Using confocal microscopy, we investigate the autofluorescence properties of five species of nematode eggs and observe clear differences between genus and for the first time their species in sludge samples. This non-invasive imaging technique could lead to better understanding of these species and may assist in early control of diseases.

Detection of Helminth Ova in Wastewater Using Recombinase Polymerase Amplification Coupled to Lateral Flow Strips

Abstract: Ascaris lumbricoides is a major soil-transmitted helminth that is highly infective to humans. The ova of A. lumbricoides are able to survive wastewater treatment, thus making it an indicator organism for effective water treatment and sanitation. Hence, Ascaris ova must be removed from wastewater matrices for the safe use of recycled water. Current microscopic techniques for identification and enumeration of Ascaris ova are laborious and cumbersome. Polymerase chain reaction (PCR)-based techniques are sensitive and specific, however, major constraints lie in having to transport samples to a centralised laboratory, the requirement for sophisticated instrumentation and skilled personnel. To address this issue, a rapid, highly specific, sensitive, and affordable method for the detection of helminth ova was developed utilising recombinase polymerase amplification (RPA) coupled with lateral flow (LF) strips. In this study, Ascaris suum ova were used to demonstrate the potential use of the RPA-LF assay. The method was faster (< 30 min) with optimal temperature at 37 °C and greater sensitivity than PCR-based approaches with detection as low as 2 femtograms of DNA. Furthermore, ova from two different helminth genera were able to be detected as a multiplex assay using a single lateral flow strip, which could significantly reduce the time and the cost of helminth identification. The RPA-LF system represents an accurate, rapid, and cost-effective technology that could replace the existing detection methods, which are technically challenged and not ideal for on-site detection in wastewater treatment plants.

Renewable energy from the solid-state anaerobic digestion of grape marc and cheese whey at high treatment capacity

Abstract: Globally, wine production annually generates some 11 million metric tonnes of grape marc (GM) while the cheese-making industry releases over 200 million m3 y−1 of effluent. Where value-creation mechanisms are absent, such wastes may be channelled to landfills. The study aimed to evaluate the bioenergy potential of the combined treatment of such wastes. Digestion of feedstock at a ratio 3/1 GM/CW (w/w) was conducted in unstirred conditions at 45 °C, following optimisation through the Taguchi Method. Cumulative biogas and methane yields were 0.601 m3 gas kg−1 VS and 0.363 m3 CH4 kg−1 VS, respectively. Firmicutes and Bacteroides mediated hydrolysis and acidogenesis, thus providing metabolites to Methanosarcina. Co-digestion can potentially generate 1330 GW h and 482,000 Mt CO2-equivalents avoidance. Wine and dairy industries jointly present a case for value-creation through a circular economy, thereby reducing the dependency on non-renewables, renewing commitment to the Paris Agreement.

Analysis of the Microbiome (Bathing Biome) in Geothermal Waters from an Australian Balneotherapy Centre

Abstract: Balneotherapy is an ancient practice which remains commonplace throughout the world due to perceived health benefits that include relief of arthritis, fibromyalgia and relaxation. However, bathing environments are not sterile and natural spring waters may harbour natural microbial populations that include potential pathogens. We elucidated the microbial community from water taken from the borehole, pre-filter water (chlorinated, cold and post-bathing water) and post-filter water at a commercial Australian natural hot spring bathing facility. Thiobacillus, Sphingobium and Agrobacterium were the predominant genera in samples collected from the borehole. The predominant genera changed to Sphingobium, Parvibaculum and Achromobacter following chloride treatment and Azospira replaced the Achromobacter once the water reached ambient temperature and was stored ready to be used by bathers. The microbial community changed again following use by bathers, dominated by Pseudomonas, although Sphingobium persisted. No total or faecal coliforms were observed in any of the samples except for the post-bathing water; even there, their presence was at very low concentration (2.3 cfu/mL). These results confirm the lack of pathogens present in these hot spring waters but also suggests that good management of post-bathing water is required especially if the water is used for borehole water recharge.

Green synthesis of Opuntia-derived carbon nanodots for the catalytic decolourization of cationic dyes

Abstract: The continued discharge of synthetic dyes into aqueous ecosystems from industrial effluent sources represents a critical issue for both human and environmental health. Although there exist various treatments for the treatment of dye-containing wastewater, a low-cost, green, effective, and ecofriendly approach still remains to be developed. In this work, carbon nanodots were synthesised using prickly pear and urea as green precursors and tested as catalysts in the Fenton-like reaction for the catalytic decolourization of cationic dyes. Approximately 90% of a mix of three common cationic dyes (crystal violet, basic fuchsin and methyl green) at 5 × 10−5 M were removed from water at 20 °C and pH 7.5 in the presence of H2O2 at 0.5% after only 60 minutes. The carbon nanodots utilised in this study were characterized by FTIR, XPS, zeta potential, UV-Vis and TEM. They exhibited negative surface charge, excellent aqueous solubility, and nitrogen rich surface functionalities which were involved in the transference of electrons, participating in the decomposition of H2O2, and therefore generated hydroxyls, superoxide ions and singlet oxygens as detected using the free radical quenching technique. This work provides an insight into exploiting an ecofriendly non-toxic metal-free catalyst using a low cost and efficient approach that showed promising decolourization results, without the use of external energy, at a neutral pH solution that could be potentially applied in catalysis of a range of environmental pollutants.

The toxicity of coated silver nanoparticles to the alga Raphidocelis subcapitata

Abstract: The use of silver nanoparticles (AgNPs) is growing exponentially, especially in consumer products due to their excellent antimicrobial properties. However, concerns are growing on their possible negative effects on environmental and human health. AgNPs from consumer products enter aquatic ecosystems where their physicochemical properties including surface functionalization are critical to their impact on aquatic organisms. The effects of AgNPs coated with three different ligands; tyrosine (T-AgNP), epigallocatechin gallate (E-AgNP) and curcumin (C-AgNP) and Ag+ ions on the freshwater green alga Raphidocelis subcapitata were investigated. Stability tests of AgNPs revealed that the coating significantly affects the fate and behaviour of AgNPs. All types of AgNPs tested and ionic silver were found to be toxic to the alga and differential growth inhibition of algae were observed from differently coated AgNPs, with the 48 h EC50 of C-AgNPs, T-AgNPs and E-AgNPs being 0.155, 0.163 and 0.243 mg L−1, respectively, in comparison with 0.051 mg L−1 for Ag+ ions. Associated Ag in the algae increased with increased concentrations of all AgNPs and Ag+ ions and the toxicity positively correlated to the associated Ag content in algae. The antioxidant enzymes glutathione S-transferase and catalase were activated in algal cells by the AgNPs and Ag+ ions, but a consistent difference in response was not identified with different concentrations of NPs. This study shows the effects of the surrounding environment and surface functionalization of AgNPs on algae highlighting the importance of considering them in environmental risk assessment of AgNPs.

Are Sterols Useful for the Identification of Sources of Faecal Contamination in Shellfish? A Case Study

Abstract: This work aimed to identify the major source(s) of faecal pollution impacting Salcott Creek oyster fisheries in the UK through the examination of the sterol profiles. The concentration of the major sewage biomarker, coprostanol, in water overlying the oysters varied between 0.01 µg L−1 and 1.20 µg L−1. The coprostanol/epicoprostanol ratio ranged from 1.32 (September) to 33.25 (February), suggesting that human sewage represents the key input of faecal material into the estuary. However, a correlation between the sterol profile of water above the oysters with that of water that enters from Tiptree Sewage Treatment Works (r = 0.82), and a sample from a site (Quinces Corner) observed to have a high population of Brent geese (r = 0.82), suggests that both sources contribute to the faecal pollution affecting the oysters. In identifying these key faecal inputs, sterol profiling has allowed targeted management practices to be employed to ensure that oyster quality is optimised.

Co-Digestion of Grape Marc and Cheese Whey at High Total Solids Holds Potential for Sustained Bioenergy Generation.

Abstract: At the end of fermentation, wine contains approximately 20% (w/v) of solid material, known as grape marc (GM), produced at a yield of 2 t/ha. Cheese manufacture produces cheese whey (CW), which is over 80% of the processed milk, per unit volume. Both waste types represent an important fraction of the organic waste being disposed of by the wine and dairy industries. The objective of this study was to investigate the bioenergy potential through anaerobic codigestion of these waste streams. The best bioenergy profile was obtained from the digestion setups of mixing ratio 3/1 GM/CW (wet weight/wet weight). At this ratio, the inhibitory salinity of CW was sufficiently diluted, resulting in 23.73% conversion of the organic material to methane. On average, 64 days of steady bioenergy productivity was achieved, reaching a maximum of 85 ± 0.4% CH4 purity with a maximum cumulative methane yield of 24.4 ± 0.11 L CH4 kg-1 VS. During the fermentation there was 18.63% CODt removal, 21.18% reduction of conductivity whilst salinity rose by 36.19%. It can be concluded that wine and dairy industries could utilise these waste streams for enhanced treatment and energy recovery, thereby developing a circular economy.

A Review of Dry Sanitation Systems

Abstract: Dry sanitation systems (waterless or composting toilets) have been used since the 1970s. Their use has received acceptance in rural regions of Europe and the United States. Some of the advantages of dry sanitation systems include their waterless nature, their low energy requirement and the creation of fertilizer as an added value product. Moreover, the use of such a system is a sustainable sanitation approach that may reduce the burden on infrastructure and provide sanitation to the 2.5 billion people worldwide who do not currently have access to it. The critical factors when choosing a dry sanitation system and their optimum parameters include aeration, moisture content (50%–60%), temperature (40–65 °C), carbon to nitrogen ratio (25–35), pH (5.5–8.0) and porosity (35%–50%). The temperature–time criterion approach is the most common method used to evaluate the stability and safety of the compost as a fertilizer. The risks of handling the waste after 12 months of composting have been calculated as low. Here, we have reviewed and assessed the features of dry sanitation systems currently available, focusing on those designed for and operated in remote areas such as national parks and tourist destinations and, more importantly, in rural areas in developing countries or refugee shelters where water/sanitation may be scarce.

Measuring Soil Metal Bioavailability in Roadside Soils of Different Ages

Abstract: Finding a reliable method to predict soil metal bioavailability in aged soil continues to be one of the most important problems in contaminated soil chemistry. To investigate the bioavailability of metals aged in soils, we used roadside soils that had accumulated metals from vehicle emissions over a range of years. We collected topsoil (0–10 cm) samples representing new-, medium- and old-aged roadside soils and control site soil. These soils were studied to compare the ability of the diffusive gradients in thin films technique (DGT), soil water extraction, CaCl2 extraction, total metal concentrations and optimised linear models to predict metal bioavailability in wheat plants. The response time for the release of metals and the effect on metal bioavailability in field aged soils was also studied. The DGT, and extractable metals such as CaCl2 extractable and soil solution metals in soil, were not well correlated with metal concentrations in wheat shoots. In comparison, the strongest relationships with concentrations in wheat shoots were found for Ni and Zn total metal concentrations in soil (e.g., Ni r = 0.750, p = 0.005 and Zn r = 0.833, p = 0.001); the correlations were still low, suggesting that total metal concentrations were also not a robust measure of bioavailability. Optimised linear models incorporating soil physiochemical properties and metal extracts together with road age as measure of exposure time, demonstrated a very strong relationship for Mn R2 = 0.936; Ni R2 = 0.936 and Zn R2 = 0.931. While all the models developed were dependent on total soil metal concentrations, models developed for Mn and Zn clearly demonstrated the effect of road age on metal bioavailability. Therefore, the optimised linear models developed have the potential for robustly predicting bioavailable metal concentrations in field soils where the metals have aged in situ. The intrinsic rate of release of metals increased for Mn (R2 = 0.617, p = 0.002) and decreased for Cd (R2 = 0.456, p = 0.096), Cu (R2 = 0.560, p = 0.083) and Zn (R2 =0.578, p = 0.072). Nickel did not show any relationship between dissociation time (Tc) and road age. Roadside soil pH was likely to be the key parameter controlling metal aging in roadside soil.