Seaweed-Eating Bacteria Produce Biodegradable Plastic, Offer Solution in Fighting Waste Pollution

Plastic proliferation and global warming have become the most alarming environmental issue today. The United Nations predicts that by the year 2050, there will be more plastics than fish in the oceans. Although recycling is one of the most promoted solutions, it does not solve the problem brought about by the massive production of single-use plastic products.

Bioplastics from Renewable Ingredients

Bioprocess engineer Jesús E. Rodríguez attempts to address this challenge by making compostable plastic. With his team at ULUU biotechnology company in Watermans Bay, Australia, Rodríguez aims to replace all synthetic plastics using biopolymers.

Only three renewable ingredients are used in this project: seaweed, seawater, and saltwater microbes. The saltwater microbes used in this project naturally produce a type of polymer known as polyhydroxyalkanoates (PHAs). These PHAs are biodegradable even in cold, dark environments such as deep seabed, thus, showing potential in replacing many types of synthetic plastics. As seawater solution is added to a colony of bacteria, it causes the cells of the microbes to explode, releasing PHAs into the solution. Unlike other forms of bioplastics, this material can also degrade in household waste.

Most producers of biopolymers use glucose obtained from maize corn or sugar cane. In this project, the research team prefers to use seaweed as the carbon source for fermentation, similar to beer production from hop fermentation. Seaweed has more advantages since it can grow quickly and cheaply without removing it from the global food supply.

The team's bioplastics were tested for use in items such as buttons and containers. In the future, they aim to provide alternatives for any synthetic plastics industry, such as packaging and stationery. As of now, they are currently creating sustainable fiber for textile products.

Achieving Sustainability with Polyhydroxyalkanoates

Due to environmental issues and the challenges of limited petroleum sources, polymers from renewable sources have gained significant attention over the past decades. Among the natural polymers are polyhydroxyalkanoates (PHAs), a family of natural biodegradable polyesters synthesized by various microorganisms for intracellular carbon and energy storage.

PHAs are used by bacteria to store energy when nutrients for reproduction are not enough. Over 150 PHAs with various polymer structures have been found by scientists. The type of PHA produced depends on the type of bacteria and their diet, which can be starches, methane, sugars, triglycerides, or glycerin.

One of the most exciting properties of PHAs is biodegradability. Unlike some polymers, which only break down in an industrial composting facility, PHAs can decompose even in ambient environments. They also manifest physical properties comparable to polyethylene and polypropylene, the materials used in making conventional plastic products. Because of these characteristics, PHAs are considered the potential solution to addressing the problems of pollution brought by the accumulation of non-biodegradable plastic products.

However, PHAs have some limitations when applied as an alternative biomaterial. These include limited functionalities, high production cost, and susceptibility to thermal degradation. Because of this, there is a need to modify PHAs to ensure improved performance in specific functions.