Bacterial slime is cunning stuff. More technically known as biofilm, it is a joint venture between large numbers of bacteria that form multicultural communities on any surface, including underwater surfaces. Biofilms also extrude sticky, slimy mucous polymers that give them structured and protected habitats, and keep out dangerous substances such as antibacterial products.
Bacteria are capable of a process called ‘quorum sensing’, which lets them communicate and cooperate chemically. In the case of biofilms that corrode oil and gas pipelines, the bacteria that need to access dissolved oxygen live on top and provide a handy barrier to protect the bacteria that find oxygen toxic. This allows them to grow and produce agents able to eat through steel.
The corrosive capacity is due to acid-producing bacteria (APB). These turn dissolved oxygen into weak organic acids, and sulfate-reducing bacteria (SRB) that consume the weak organic acid, combine it with sulfates from oil and water and produce hydrogen sulphide that corrodes steel and other metals. This process costs the oil and gas industry hundreds of millions of dollars each year in chemicals and production downtime.
Human vs slime
To date most human attempts to kill or eradicate slime from underwater surfaces, such as oil and gas industry infrastructure, have involved the use of traditional biocides.
Pipeline cleaning also involves the use of rubber and wire brush pigs that work a bit like a bottlebrush scrubbing the sides as they push through the pipes.
Despite oil and gas companies spending money and time on these strategies, biofilm quickly regrows, contributing to the need for replacement parts and representing a serious ongoing expense.
A new approach to slime control
University of New South Wales Professor Peter Steinberg, now an executive director of Biosignal, was scuba diving with a group of students collecting marine life samples in Botany Bay, when they noticed that only one seaweed species was not covered with algae and other biological fouling. Intrigued, they plucked a sample of the rogue plant and took it back to the lab.
It turns out that this seaweed, Delisea pulchra, produced molecules that had the ability to disrupt the bacterial signalling process.
By scrambling the chemical signalling of the bacteria trying to form colonies on its fronds, it halted the biofilm formation process, leaving other organisms with nothing to get a grip on.
The seaweed’s secret involves chemicals that are antagonistic to the bacterial signalling process. One of the key signalling systems is called the AHL system. The UNSW team has since proceeded to synthesise and evaluate more than 300 variations of Delisea’s natural blockers of the AHL system.
The corporate vehicle
In 1999 the University of NSW formed a spinoff company called Biosignal to commercialise the AHL-A intellectual property.
After listing on the ASX in 2004, Biosignal’s first project was the commercialisation of the anti-biofilm technology for reducing the build-up of infection-causing bacteria on contact lenses and medical devices.
Biosignal also signed a collaborative agreement with a privately held Melbourne-based company called Q.Stat to develop new solutions to the hydrocarbon fuel contamination and oil and gas infrastructure degradation caused by biofilms.
This collaboration now has data from a four-month study by the CSIRO Division of Manufacturing and Infrastructure evaluating the activity of a range of candidates from Biosignal’s library against bacteria and fungi causing metal corrosion. This study, using aluminium metal coupons, confirmed and quantified experiments conducted at the University of Connecticut that used steel coupons.
BHP Billiton Petroleum and Santos have also come on board offering funding for the continuation of this project.
Biosignal chief executive Michael Ordesson says the company’s technology was showing potential to significantly reduce the use of more toxic antibacterial products by making biofilms more permeable and reducing their ability to reform after pigging.
Ordesson said Biosignal’s initial objective was to significantly reduce current levels of biocides used in oil and gas pipelines and also reduce the frequency of required cleaning leading to further savings.
“On top of that we aim to achieve savings as a result of reductions in the rate of degradation of parts and equipment and reduced environmental and occupational health and safety risks,” he said.
With revenue already coming in from grants and commercial collaborations, its contact lenses are expected to be on the market by 2008. Ordesson said Biosignal was considering spinning out the oil and gas industry applications into its own company.
“If the results that we get from the corrosion trials underway over the next few months are as good as the results we have had to date, products could be on the market within the next few years,” he said.
