22 April 2015

Bacteria, fungi offer solutions to polluting plastics

By Dr Moritz Mueller

Most of us will have spent a weekend at a beautiful beach admiring the ocean view. What most of us don’t know is that the sea close to the coast, the sea shelf up to a depth of 200m, makes up only 5% of the world’s oceans but it is home to around 20% of all life in the ocean. While we don’t fully understand how this small area can sustain this much biological growth we do know that it sustains 90% of the world’s fisheries. It is one of the most important ecosystems on Earth.

Unfortunately, with so many people living along the coasts there is inevitable pressure on these ecosystems. A recent study published in the Science journal has found that coastal populations worldwide put about eight million tonnes of plastic rubbish into the oceans every year. This number is predicted to double by 2025. According to the same report, the cumulative amount of plastic in the seas will soar 10-fold by 2025 if we do nothing to reduce waste generation or improve its management.

The same study also found that Malaysia is the eighth worst polluter in the world, a fact we were reminded of by the recent death of a dolphin in Kota Kinabalu. The Borneo Post reported last month that the mammal had mistaken plastic bags floating in the sea for food. A post-mortem by Universiti Malaysia Sabah’s Borneo Marine Research Institute revealed that its stomach contained 44 pieces of plastic materials, weighing a total of 4.25kg. As a result, the dolphin died from chronic starvation since its stomach did not contain any food because no food could pass through all that plastic. Many other marine creatures such as turtles have in the past been found dead with plastic bags in their digestive system. Almost anything we use today contains plastic – computers, mobile phones, shopping bags, cups – can potentially end up in the ocean. So, what can we do to prevent more innocent animals dying from our rubbish?

One way is to create more environmentally friendly plastics. Scientists have developed genetically modified bacteria that can synthesise plastic. These biologically created plastics are biodegradable, do not require petroleum to produce and are renewable as opposed to the commonly used crude oil. Scientists can create the plastics in a lab with the correct materials and bacterial strains. Bacteria store the plastics as food in little granules for later use and humans can harvest these granules to create bioplastics. Instead of using expensive oil or natural gas to make BDO, an important commodity chemical used to manufacture over 2.5 million tons of valuable plastic polymers annually; scientists have recently developed strains of bacteria that can produce BDO with water and sugar. These genetically engineered bacteria can be grown in large fermentation tanks, similar to how microalgae are grown to produce biofuels. In future, new plastic containers made from BDO could one day hold your peanut butter sandwich instead of today’s which requires energy intensive processes to produce.

Improving the production efficiency of bacterial derived plastics could completely transform the plastics industry. However, two main challenges need to be solved to make it economically competitive with petrochemicals: achieving efficient production of feedstock chemicals, and achieving the efficient production of the bioplastics. Both these challenges, of course, revolve around giving enough bacteria the proper conditions to mass-produce plastic polymers. Biotechnology offers many possible solutions and play a key role in the future development and success of bioplastics. At this point, many business ventures are privately funded and in the early stages. The potential upside for this industry, however, is astronomical.

Another solution in which biotechnology also plays a key role is to develop better recycling options. Biological means, mostly in the form of bacteria or fungi, have successfully been used to degrade some plastic polymers (bioremediation). At the university, we have identified fungi living inside the common Nipa palm that “eats” plastic. An interesting feature of these fungi is that they are also able to live in relatively high concentrations of harmful heavy metals such as copper and lead. We hope to use these fungi in the future to degrade the plastic content of electronic waste like laptop screen and mobile phones. Electronic devices often contain hundreds of different substances, many of which are toxic, have adverse effects on humans and causes serious pollution upon disposal.

The “local” fungi we found also have enormous potential for bioremediation purposes, and we hope to tailor-make them for bioremediation applications in Malaysia. This would benefit the country in combating e-waste pollution and also aid the economy by developing new green technology.

Dr Moritz Mueller is a lecturer with the Faculty of Engineering, Computing and Science at Swinburne University of Technology Sarawak Campus. He is contactable at mmueller@swinburne.edu.my