New paper on the toxicity of silver nanoparticle published!

Our new paper on silver nanoparticle toxicity on environmental bacteria is now available online. It is published in the Journal of Microbiology, Immunology and Infection (Elsevier). Read the article here.

Abstract

Background/Purposes

Silver nanoparticles (AgNPs) are currently important in various industrial applications. However, the impact upon their release into the environment on the microorganisms remains unclear. The aim of this study was to analyse the effect of polyvinylpyrrolidone (PVP)-capped AgNPs synthesized in this lab on two bacterial strains isolated from the environment; Gram-negative Citrobacter sp. A1 and Gram-positive Enterococcus sp. C1.

Methods

PVP-capped AgNPs were synthesized by ultrasound-assisted chemical reduction. Characterization of the AgNPs involved UV-Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. Citrobacter sp. A1 and Enterococcus sp. C1 were exposed to varying concentrations of AgNPs and cell viability determined. Scanning electron microscopy was done to evaluate the morphological alteration on both species upon exposure to AgNPs at 1000 mg/L.

Results

AgNPs synthesized were spherical in shape with an average particle size of 15 nm. The AgNPs had different but prominent effects on either Citrobacter sp. A1 or Enterococcussp. C1. At 1000 mg/L AgNPs, Citrobacter sp. A1 retained viability for 6 h while Enterococcus sp. C1 only 3 h. Citrobacter sp. A1 appeared to be more resistant to AgNPs than Enterococcus sp. C1. The cell wall of both strains was found to be morphologically altered at that concentration.

Conclusions

Minute and spherical AgNPs significantly affected the viability of the two bacterial strains selected from the environment. Enterococcus sp. C1 was more vulnerable to AgNPs, probably due to its cell wall architecture and the absence of silver resistance-related genes.

ACS South East Asia Global Innovation Challenge Competition (SEAGIC) for Undergraduates

American Chemical Society (ACS) Malaysia is inviting all undergraduate students in South East Asian region to submit their ideas to the ACS SEAGIC on water sustainability issues. There is not entry fee, and selected entries will be invited to attend the final round at UTM Skudai, Johor, Malaysia (with sponsored accommodation), for a chance to pitch their ideas in front of a panel of judges. Cash prizes, trophies and certificates await the best ideas!

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Latest publication!

Bioresource-Technology

Our paper on bioelectricity generation using POME in an MFC has been published in Bioresource Technology. Read the article here.

 

ABSTRACT

A double-chambered membrane microbial fuel cell (MFC) was constructed to investigate the potential use of natural microflora anaerobic palm oil mill effluent (POME) sludge and pure culture bacteria isolated from anaerobic POME sludge as inoculum for electricity generation. Sterilized final discharge POME was used as the substrate with no addition of nutrients. MFC operation using natural microflora anaerobic POME sludge showed a maximum power density and current density of 85.11 mW/m2 and 91.12 mA/m2 respectively. Bacterial identification using 16S rRNA analysis of the pure culture isolated from the biofilm on the anode MFC was identified as Pseudomonas aeruginosa strain ZH1. The electricity generated in MFC using P. aeruginosa strain ZH1 showed maximum power density and current density of 451.26 mW/m2 and 654.90 mA/m2 respectively which were five times higher in power density and seven times higher in current density compared to that of MFC using anaerobic POME sludge.

Congratulations!

Congratulations to Naglea A. E. Lagehr on passing her Master of Science (Biotechnology) viva! She was working on detection and amplification of putative hydrogenase 3 operon in Citrobacter sp. L17. Well done!

New Publication

Our review paper on photosynthetic bacteria has been published in the Reviews in Environmental Science and Bio/Technology, a Springer journal. Read the article here.

Abstract

Environmental management is crucial for sustainable growth and development. The use of microorganisms to clean up contaminated environment provides cheap alternative method to the conventional treatment methods. But the choice of easily grown, viable and effective natural occurring microorganism to do the cleaning is a major challenge. In this article we presented and reviewed the application of photosynthetic bacteria in bioremediation due to their utilisation of various kinds of pollutants, minimum nutrients requirement and the possibility of generating valuable products concomitantly cleaning the contaminated environment. Pollutants such as pesticides, heavy metals, dyes, crude oil and odour with the specific photosynthetic bacteria capable of degrading the pollutants were identified and discussed in this article. The possible value added products to be generated as well as the mechanism of degradation are also highlighted and discussed in the article. The utilisation of carbon dioxide and the generation of value added products while cleaning up polluted environment are the major advantages of using these bacteria in bioremediation and have both environmental and economic benefits.

Thank you!

Nur Atiqah Mohd Elias has just completed her research assistantship in Proteomics Lab. She was working on bacterial biohydrogen production from starch, using bacterial isolate from cattle. We would like to thank her for all the hard work over the past three months. All the best in your MSc study!

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Research Assistantship Opportunity

I have an opening for RA position leading to MSc by research degree. The project will be on bacterial biohydrogen production using starch as substrate. It involves microbiological characterisation, batch small scale fermentation and biohydrogen detection, and some molecular characterisations of hydrogen-production related genes. Immediate availability. Email me at firdausw@utm.my if interested.
For Malaysians only due to the nature of the grant.

Position opened until filled.

Update: 1 position available.

Congratulations!

Congratulations to Karzan Khalid and Idris Abdulrahman on successfully defending their MSc (Biotechnology) dissertation projects. They have been working on the isolation and characterisation of photosynthetic bacteria from the marine and aquaculture environment. Well done!