Doctor Smriti Rayu


Smriti RayuGraduated PhD 2016

Thesis Title

The interactions between xenobiotics and soil microbial communities

Research Project

One of the greatest problems that world facing today is the environmental pollution which is increasing by the passing day due to urbanisation and industrialisation. The change from non-urban to urban living has demanded intensive use of organic, nitro-aromatic, organo-phosphorus, inorganic and radioactive compounds. Carelessness combined with poor technology for disposal of contaminants aggravates the amount of pollution impacting both aquatic and terrestrial habitats. These compounds are of concern because of their toxicity, resistance to degradation and biomagnification via the food web. Biological remediation or bioremediation, for the removal of these pollutants is considered the choice of treatment method due to its ability to mineralise or degrade these pollutants into non-toxic compounds.

Methanotrophic bacteria are a unique group of methylotrophs that utilize methane for energy and biomass and have been long studied for their practical applications in degrading a wide range of organochlorine compounds. Methanotrophic bacteria mainly belong to alpha and gamma-proteobacteria group and only a fraction (less than 1%) of methanotrophs are currently cultured under current laboratory regimes. Additionally, the precise mechanisms of organochlorine degradation are not entirely understood.

My project aims to identify novel mechanisms of methane assisted bioremediation of some organochlorine compounds. This aim will be achieved by following three inter-linked objectives:

  • Laboratory Incubation to Isolate Novel Methanotrophs: This will include the development of improved isolation and enrichment protocols to study the physiological characteristics of methanotrophs.
  • Identifying Mechanism of Methane Assisted Bioremediation: This study will mainly focus on TCE and dichloromethane and investigate the kinetic aspects, such as degradation rates, toxicity and percent dehalogenation of organochlorine compounds.
  • Characterising the Mechanism Using Metagenomics:  A combined approach of enrichment and metagenomics will be used to distinguish whether pollutants are degraded by methanotrophs (co-metabolism) or by other microbes due to abundance and availability of methane assisted nutrient cycle.

Research Project Supervisors

A/Prof Brajesh Singh, Dr Uffe Nielsen and Dr Loic Nazaries


Jeffries TC, Rayu S, Nielsen UN, Lai KT, Ijaz A, Nazaries L, Singh BK, (2018) 'Metagenomic Functional Potential Predicts Degradation Rates of a Model Organophosphorus Xenobiotic in Pesticide Contaminated Soils', Frontiers in Microbiology, vol.9, Article no.147

Rayu S, Nielsen UN, Nazaries L, Singh BK, (2017) 'Isolation and Molecular Characterization of Novel Chlorpyrifos and 3,5,6-trichloro-2-pyridinol-degrading Bacteria from Sugarcane Farm Soils', Frontiers in Microbiology, vol.8, Article no.518

Rayu S, Karpouzas DG, Singh BK, (2012) 'Emerging technologies in bioremediation: Constraints and opportunities', Biodegradation, vol.23, no.6, pp 917-926

View the Thesis

» Australasian Digital Theses Online (opens in a new window)