Experts measure bacteria in wastewater purification process

Modelling its system on a biological wastewater treatment plant, the Luxembourg Centre for Systems Biomedicine (LCSB) team was able to study numerous live species of bacteria involved in the wastewater purification process.

“Bacterial ecosystems also play a major role in our health. We now have a better understanding of the laws governing their function,” said LCSB director Rudi Balling, who stressed the medical importance of these research efforts.

“The lipids from wastewater stored in the bacteria are a renewable energy source since they can be easily converted into biodiesel

LCSB group leader Paul Wilmes

Utilising its findings, the LCSB team can “corroborate and unify various ecological concepts that have been primarily formulated based on observations in macrobiotic systems such as forests, rivers and oceans - which cannot however be experimentally investigated in depth because of the sheer size of these biotopes”.

To perform its initial analyses, the research team employed Systems Biology methods - a computational method used to understand how systems properties emerge.

Wastewater treatment plants are a complex ecosystem comprising energy-rich substrates including fats, proteins, carbohydrates and many other substances that serve as nutrients for the resident bacteria, the researchers said.

Within such a system, bacteria adapt to living conditions and compete for resources - each finding a niche in which they can survive.

“The techniques developed at LCSB allow us now to unravel these processes very precisely at the molecular level,” said Emilie Muller, first author of the publication.

Muller said the basis for this are the so-called “omics” - genomics, transcriptomics, proteomics and metabolomics - combined with new bioinformatic methods for integrated data analysis.

“With these, we can determine from samples which organisms are living in the treatment plant, and what their population sizes, genetic make-up, activities and material turnovers are like,” she said.

Based on the LCSB study, Muller said it would be possible to model the material flows in the ’treatment plant’ ecosystem and describe which bacterial species will use and consume which substrate and to what degree.

Looking ahead, the research team will attempt to advance its study of wastewater treatment plant ecology.

“We want to understand what factors determine the species composition and accordingly the balance in the ecosystem,” said Muller.

For the research team, there is one species of bacteria that stands out: Microthrix parvicella.

“Microthrix is what ecologists call a generalist. The organism can adapt to very many living conditions and thereby dominate the highly fluctuating wastewater treatment plant ecosystem, said LCSB group leader Paul Wilmes.

“Each copy of the gene is a little different from the others. If the living conditions change, say when the temperature drops or the lipid composition changes, then a different lipid uptake gene adapted to that condition sets in. That way, Microthrix can survive in many different environments.”

Wilmes’ aim is to boost the activity of Microthrix to remove as many lipids from the wastewater as possible.

“The lipids from wastewater stored in the bacteria are a renewable energy source since they can be easily converted into biodiesel, for example.”

A full account of the study has been published in the journal Nature Communications.