ORCID Profile
0000-0003-1487-0974
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Publisher: American Chemical Society (ACS)
Date: 08-11-2017
Abstract: Aquatic ammonia has toxic effects on aquatic life. This work reports a gas-permeable membrane-based conductivity probe (GPMCP) developed for real-time monitoring of ammonia in aquatic environments. The GPMCP innovatively combines a gas-permeable membrane with a boric acid receiving phase to selectively extract ammonia from s les and form ammonium at the inner membrane interface. The rate of the receiving phase conductivity increase is directly proportional to the instantaneous ammonia concentration in the s le, which can be rapidly and sensitively determined by the embedded conductivity detector. A precalibration strategy was developed to eliminate the need for an ongoing calibration. The analytical principle and GPMCP performance were systematically validated. The laboratory results showed that ammonia concentrations ranging from 2 to 50 000 μg L
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/MA19006
Abstract: The use of ‘organ-on-chip' devices in microbiology research presents enormous opportunities for fundamental and translational research1–4. Yet these approaches have not been widely embraced by the microbiology field. This is particularly evident with bacteriophage (phage) research applications. Traditionally phage research has been an early adopter of experimental techniques and approaches5, having catalysed research in biotechnology, environmental biology, sequencing, and synthetic biology. Here we discuss some of the opportunities that organ-on-chip devices present to both phage and microbiology research, and provide a ‘how to' guide for researchers interested in utilising this approach.
Publisher: Elsevier BV
Date: 2023
Publisher: American Chemical Society (ACS)
Date: 30-08-2017
Abstract: The toxic effects of nanoparticles on in idual organisms have been widely investigated, while few studies have investigated the effects of nanoparticles on ubiquitous multicommunity microbial aggregates. Here, periphyton as a model of microbial aggregates, was employed to investigate the responses of microbial aggregates exposed continuously to Fe
Publisher: Wiley
Date: 26-05-2017
Abstract: Interactions among microbes determine the prevalence of harmful algal blooms that threaten water quality. These interactions can be indirectly mediated by shared resources or consumers, or through interference by the production of allelochemicals. Allelopathic interactions and resource competition have been shown to occur among algae and associated microbes. However, little work has considered seasonal influences on ecosystem structure and function. Here, we report results of our investigations on seasonal changes in the interactions between benthic microbial assemblies and the bloom forming cyanobacterium Microcystis aeruginosa. We show that phosphorus (P) competition and allelopathy by the microbial assembly vary seasonally and inhibit growth of M. aeruginosa. The interactions per unit biomass of the microbial assembly are stronger under winter than summer conditions and inhibit the recruitment of the cyanobacteria, thereby preventing the reoccurrence of cyanobacterial blooms in the following summer. The seasonality of these interactions correlates with changes in composition, metabolic activity and functional ersity of the microbial assembly. Our findings highlight the importance of competitive and allelopathic interactions in regulating the occurrence of harmful algal blooms. Our results also imply that seasonal variation of competition and allelopathy of the microbial assembly might be beneficial to adjust aquatic ecosystem structure and function.
Publisher: Elsevier BV
Date: 2011
DOI: 10.1016/J.BIORTECH.2010.08.073
Abstract: The purpose of this study was to treat complex wastewater consisting of domestic wastewater, tobacco processing and building materials washings. The proposed multi-level bioreactor consists of a biopond-biofilter, anoxic/aerobic (A/O) fluidized beds and a photoautotrophic system. The results show that when the hydraulic load of the bioreactor was 200 m3/d, it successfully and simultaneously removed the organic matter and metals. When the bioreactor was in a relatively steady-state condition, the overall average organic matter and metals removal efficiencies are as follows, COD (89%), UV245 nm-matter (91%), Cu (78%), Zn (79%) and Fe (84%). The growth conditions of the native bacterial habitat were improved, which resulted from the increase of the in bacterial ersity under the rejuvenated conditions induced by the bioreactor. The results demonstrate that the multi-level bioreactor, without a sludge treatment system, can remove heterogeneous organic matter and metals from wastewater.
Publisher: Proceedings of the National Academy of Sciences
Date: 29-06-2022
Abstract: The majority of viruses within the gut are obligate bacterial viruses known as bacteriophages (phages). Their bacteriotropism underscores the study of phage ecology in the gut, where they modulate and coevolve with gut bacterial communities. Traditionally, these ecological and evolutionary questions were investigated empirically via in vitro experimental evolution and, more recently, in vivo models were adopted to account for physiologically relevant conditions of the gut. Here, we probed beyond conventional phage–bacteria coevolution to investigate potential tripartite evolutionary interactions between phages, their bacterial hosts, and the mammalian gut mucosa. To capture the role of the mammalian gut, we recapitulated a life-like gut mucosal layer using in vitro lab-on-a-chip devices (to wit, the gut-on-a-chip) and showed that the mucosal environment supports stable phage–bacteria coexistence. Next, we experimentally coevolved lytic phage populations within the gut-on-a-chip devices alongside their bacterial hosts. We found that while phages adapt to the mucosal environment via de novo mutations, genetic recombination was the key evolutionary force in driving mutational fitness. A single mutation in the phage capsid protein Hoc—known to facilitate phage adherence to mucus—caused altered phage binding to fucosylated mucin glycans. We demonstrated that the altered glycan-binding phenotype provided the evolved mutant phage a competitive fitness advantage over its ancestral wild-type phage in the gut-on-a-chip mucosal environment. Collectively, our findings revealed that phages—in addition to their evolutionary relationship with bacteria—are able to evolve in response to a mammalian-derived mucosal environment.
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.1016/J.BIORTECH.2009.12.144
Abstract: Harmful cyanobacterial bloom in water bodies frequently occurs due to eutrophication, leading to the excessive growth of cyanobacteria which in turn may lead to a decrease in bio ersity. A biopond-wetland system to control cyanobacterial bloom and stabilize or even increase bio ersity is proposed and applied in a pond, Kunming, western China where cyanobacterial blooms frequently break out. The biopond-wetland system examined includes three main parts: filter-feeding fish, replanted pond macrophytes, and a terminal artificial wetland. When the hydraulic load of the biopond-wetland system was 500m(3)/d on non-rainy days, the system successfully decreased the level of chlorophyll-a (Chl-a). The declining levels of total nitrogen (TN), total phosphorus (TP) and ammonia in the water after establishing the biopond-wetland system also coincided with the disappearance of the cyanobacterial bloom. In the second summer, when the biopond-wetland system was in a relatively steady-state condition, the overall average nutrient removal efficiencies were as follows, Chl-a (83%), TN (57%), TP (70%) and ammonia (66%), while in the second winter, the overall average removal efficiencies were Chl-a (66%), TN (40%), TP (53%) and ammonia (49%). Simpson's ersity index of zoobenthos indicated that the system increased the zoobenthic ersity and improved the growth conditions of the zoobenthos habitat. The results demonstrated that the biopond-wetland system could control cyanobacterial blooms.
Publisher: Elsevier BV
Date: 12-2010
DOI: 10.1016/J.BIORTECH.2010.07.063
Abstract: Microporous suspended bioreactors immobilized with periphytons were submerged between sediments and overlying water to control phosphorus release and cyanobacterial (Microcystis aeruginosa) growth. The results showed that the periphyton mainly consisted of bacteria and diatoms. The application of periphyton bioreactor decreased the levels of exchange phosphorus (Exch-P) in sediments from 1.69 to 0.49 mg g(-1) and total phosphorus (TP) from 0.75 to 0.30 mg L(-1). The significant reduction of the total dissolved phosphorus (TDP) content was not only beneficial for the decrease of the cyanobacterial growth, but also stimulates the periphyton to produce natural cyanobacterial inhibitors such as gallic acid and ethyl-2-methylacetoacetate. These synergistic effects led to the growth inhabitation of M. aeruginosa when the initial concentrations of M. aeruginosa were less than 119.3 microg L(-1). This study provides an environmentally-friendly and publically acceptable method of controlling bacterial blooms when compared to traditional addition of chemicals.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.ENVPOL.2010.03.020
Abstract: An eco-restoration system to remove excess nutrients and restore the agricultural ecosystem balance was proposed and applied from August 2006 to August 2008 in a residential-cropland complex area (1.4 x 10(5) m(2)) in Kunming, western China, where the self-purifying capacity of the agricultural ecosystem had been lost. The proposed eco-restoration system examined includes three main foci: farming management, bioremediation, and wastewater treatment. The results showed that the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) from the complex wastewater were 83% and 88%, respectively. The Simpson's ersity indices of macrophytes and zoobenthos indicated that the system had increased macrophyte and zoobenthic ersity as well as improved growth conditions of the plankton habitats. The results demonstrated that the proposed eco-restoration system is a promising approach for decreasing the output of nutrients from soil, improving agricultural ecosystem health, and minimizing the downstream eutrophication risk for surface waters.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.BIORTECH.2016.11.115
Abstract: The aim of this study was to evaluate the bioremediation capabilities of three kinds of periphyton (i.e. epiphyton, metaphyton and epilithon) immobilized in bioreactors to decolorize and biodegrade the sulphonated azo dye, amaranth. Results showed that periphyton dominated by phyla including Cyanobacteria, Proteobacteria and Bacteroidetes. Complete removal of dye was shown by all the biofilms periphyton (epiphyton showed highest removal efficacy) over a range of initial concentrations (50-500mgL
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7EN00352H
Abstract: The roles of different extracellular polymeric substance fractions of a periphytic biofilm in defending against Fe 2 O 3 nanoparticle toxicity.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.BIORTECH.2011.08.090
Abstract: The aim of this project was to establish an economical and environmentally benign biotechnology for removing methylene blue (MB) from wastewater. The adsorption process of MB onto abandoned sesame hull (Sesamum indicum L.) (SH) was investigated in a batch system. The results showed that a wide range of pH (3.54-10.50) was favorable for the adsorption of MB onto SH. The Langmuir model displayed the best fit for the isothermal data. The exothermic adsorption process fits a pseudo-second-order kinetic model. The maximum monolayer adsorption capacity (359.88 mg g(-1)) was higher than most previously investigated low-cost bioadsorbents (e.g., peanut hull, wheat straw, etc.). This study indicated that sesame hull is a promising, unconventional, affordable and environmentally friendly bio-measure that is easily deployed for removing high levels of MB from wastewater.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.BIORTECH.2010.10.113
Abstract: The aim of this project was to establish an economical and environmentally benign biotechnology for removing nutrients from non-point source wastewater. The proposal involves a hybrid bioreactor comprised of sequential anaerobic, anoxic and aerobic (A(2)/O) processes and an eco-ditch being constructed and applied in a suburban area, Kunming, south-western China, where wastewater was discharged from an industrial park and suburban communities. The results show that the hybrid bioreactor fosters heterotrophic and autotrophic microorganisms. When the hydraulic load is 200 m(3) per day with the running mode in 12h cycles, the removal efficiencies of the nutrients were 81% for TP, 74% for TDP, 82% for TN, 79% for NO(3)-N and 86% for NH(4)-N. The improved bacterial community structure and bacterial habitats further implied enhanced water quality and indicates that the easily-deployed, affordable and environmentally-friendly hybrid bioreactor is a promising bio-measure for removing high loadings of nutrients from non-point source wastewater.
Publisher: Cold Spring Harbor Laboratory
Date: 08-09-2020
DOI: 10.1101/2020.09.07.286716
Abstract: For over 100 years, bacteriophages have been known as viruses that infect bacteria. Yet it is becoming increasingly apparent that bacteriophages, or phages for short, have tropisms outside their bacterial hosts. During phage therapy, high doses of phages are directly administered and disseminated throughout the body, facilitating broad interactions with eukaryotic cells. Using live cell imaging across a range of cell lines we demonstrate that cell type plays a major role in phage internalisation and that smaller phages ( 100 nm) are internalised at higher rates. Uptake rates were validated under physiological shear stress conditions using a microfluidic device that mimics the shear stress to which endothelial cells are exposed to in the human body. Phages were found to rapidly adhere to eukaryotic cell layers, with adherent phages being subsequently internalised by macropinocytosis and functional phages accumulating and stably persisting intracellularly. Finally, we incorporate these results into an established pharmacokinetic model demonstrating the potential impact of phage accumulation by these cell layers, which represents a major sink for circulating phages in the body. Understanding these interactions will have important implications on innate immune responses, phage pharmacokinetics, and the efficacy of phage therapy.
Publisher: American Chemical Society (ACS)
Date: 07-06-2019
DOI: 10.1021/ACSSENSORS.9B00768
Abstract: Ammonia is a necessary monitoring parameter that should be controlled within an optimum range in the whole process of wastewater treatment and recycling, but few reliable real-time monitoring technologies are available currently under such harsh water conditions. This study proposes a continuous conductometric flow-through analyzer for ammonia monitoring (CFAA) in the wastewater treatment process. It is developed based on the gas diffusion mechanisms, and the proposed analytical principle has been validated in which the real-time conductivity increment rate is linearly proportional to the real-time ammonia concentration in the s le. This method could be generally applicable in monitoring a wide ammonia concentration range (10.2 μg L
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.BIORTECH.2013.10.088
Abstract: Environmentally benign and sustainable biomeasures have become attractive options for the in situ remediation of polluted surface waters. In this paper, we review the current state of reported experiments utilizing naturally occurring periphyton. These are microbial communities consisting of heterotrophic and photoautotrophic microorganisms that are reportedly capable of remediating surface waters which suffer from pollution due to a variety of contaminants. In our review, we focus on four aspects of bioremediation: multiple contaminant removal, the processes involved in contaminant removal, successful cell immobilization technologies and finally, the consideration of safety in aquaculture. It has been noted that recent developments in immobilization technologies offer a fresh approach facilitating the application of periphyton. The use of periphyton biofilm overcomes several disadvantages of single species microbial aggregates. The inclusion of periphyton, as a stable micro-ecosystem, is a promising in situ strategy to restore decimated surface water ecosystems.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.CHEMOSPHERE.2016.10.002
Abstract: Due to their large scale use, azo dyes are adversely affecting aquatic fauna and flora as well as humans. The persistent nature of sulphonated azo dyes makes them potential ecotoxic hazards. The aim of the present study was to employ a proficient, locally available biomaterial, viz. periphyton (i.e. epiphyton, epilithon or metaphyton), for removal of the azo dye, methyl orange (MO). Results showed that the periphytic biofilms are capable of completely removing comparatively high concentrations (up to 500 mg L
Publisher: Public Library of Science (PLoS)
Date: 08-2012
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ECOENV.2011.01.014
Abstract: Many measures have been developed to control the harmful algal blooms that are potentially threatening potable waters. The pilot experiments showed that the unfiltered and the sterile-filtered decoctions of radix Astragali inhibited the growth of Microcystis aeruginosa. The inhibitory effect diminished in natural pond conditions after 68 days, due to photo-degradation of the flavonoids from radix Astragali that appear to be responsible for the action on M. aeruginosa. Four phases (assemblage, conglomeration, cell membrane destruction and decomposition) can be characterized in the process of cell death with increasing decoction dose. The quantum yields and electron transport rates of photosynthesis system II of M. aeruginosa cells markedly decreased during contact with the decoction, resulting in the disruption of M. aeruginosa photosynthesis. The results indicate that the application of radix Astragali decoction for the inhibition of M. aeruginosa growth is feasible when the dose is less than 20 ml L(-1).
Publisher: Wiley
Date: 05-11-2010
DOI: 10.1111/J.1462-2920.2010.02363.X
Abstract: Periphyton biofilms are natural mixtures comprised of photoautotrophic and heterotrophic complex microorganisms. In this work, the inhibition effects of periphyton biofilms on cyanobacterial blooms were studied in pilot and field trials. Results show that the cyanobacterial species responsible for the blooms had an upper nutrient concentration threshold, below which it could not effectively compete with other organisms in the periphyton. The disappearance of the cyanobacterial blooms was due to the allelopathy between the cyanobacteria and periphyton biofilm. In particular, it was found that the periphyton biofilm could produce water-soluble allelochemicals such as indole and 3-oxo-α-ionone to significantly inhibit the growth of the cyanobacteria. These allelochemicals are able to damage the thylakoid membranes of the cyanobacteria, interrupt the electron transport in photosystem II, decrease effective quantum yields, and eventually lead to the failure of photosynthesis. A comprehensive discussion on the ecological consequences of these findings is also presented. This work demonstrates the potential of periphyton biofilm to be used as an environmentally friendly ecological engineering solution for (i) the control of cyanobacterial blooms and (ii) a transitional means for the construction of beneficial conditions for ecosystem restoration. In addition, this work provides significant insights into the competitive relationships between algae and biofilms.
Publisher: Cold Spring Harbor Laboratory
Date: 11-05-2021
DOI: 10.1101/2021.05.11.443681
Abstract: The majority of viruses within the human gut are obligate bacterial viruses known as bacteriophages (phages) 1 . Their bacteriotropism underscores the study of phage ecology in the gut, where they sustain top–down control 2—4 and co–evolve 5 with gut bacterial communities. Traditionally, these were investigated empirically via in vitro experimental evolution 6—8 and more recently, in vivo models were adopted to account for gut niche effects 4,9 . Here, we probed beyond conventional phage–bacteria co–evolution to investigate the potential evolutionary interactions between phages and the mammalian ″host″. To capture the role of the mammalian host, we recapitulated a life–like mammalian gut mucosa using in vitro lab–on–a–chip devices (to wit, the gut–on–a–chip) and showed that the mucosal environment supports stable phage–bacteria co–existence. Next, we experimentally evolved phage populations within the gut–on–a–chip devices and discovered that phages adapt by de novo mutations and genetic recombination. We found that a single mutation in the phage capsid protein Hoc — known to facilitate phage adherence to mucus 10 — caused altered phage binding to fucosylated mucin glycans. We demonstrated that the altered glycan–binding phenotype provided the evolved mutant phage a competitive fitness advantage over their ancestral wildtype phage in the gut–on–a–chip mucosal environment. Collectively, our findings revealed that phages — in addition to their evolutionary relationship with bacteria — are also able to engage in evolution with the mammalian host.
Publisher: American Chemical Society (ACS)
Date: 11-08-2017
Abstract: Allelopathy among aquatic organisms, especially microorganisms, has received growing attention in recent years for its role in shaping interactions with bloom-forming algae. Many studies have shown that allelopathy occurs and increases under nutrient limiting conditions. However, to date there is no reported direct evidence to indicate that allelopathy occurs under the condition of constant high nutrient supply. Here we report the allelopathic action of periphytic biofilm on bloom-forming cyanobacteria (Microcystis aeruginosa), which was triggered by the stress of high nutrient conditions, and continues while nutrients are maintained at high levels (trophic state index at 159 and 171). The experimental evidence indicates that the electron transport from photosystem II (PS II) to photosystem I (PS I) in M. aeruginosa is interrupted by the identified allelochemicals, (9Z)-Octadec-9-enoic acid and (9Z)-Hexadec-9-enoic acid, leading to the failure of photosynthesis and the subsequent death of M. aeruginosa. Our findings indicate that the nutrient stress of constant high nutrient supply may be a newly recognized trigger causing allelopathy between microbial competitors, and therefore opening a new direction for the better management of ecological processes in cyanobacteria-dominated and hyper-eutrophic waters.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Wai Hoe Chin.