Cellulose synthase complex configuration effects in microalgal cellulose

Project background (identification of the problem and its importance and relevance to sustainability)

Due to the current global food trade, plastic packaging has become essential in modern infrastructure. However, plastic, particularly single use, is causing negative environmental impacts. After use, only 14% of plastic is collected for recycling, with 32% being released into the environment.

Plastic cannot be degraded by biotic factors and instead breaks down slowly to form microplastics that accumulate in the environment causing damage to humans and other organisms. One answer to this crisis is to replace conventional plastic materials with bioplastics. Bioplastics are plastic made from renewable resources, such as terrestrial crops, agricultural waste, or fast-growing microorganisms.

Cellulose is the most abundant biopolymer in nature and is synthesised by many different organisms. Regenerated cellulose films could be ideal for food packaging due to their good barrier functionality, mechanical properties, biodegradability, and renewability. However, there are concerns about where a large amount of cellulose could be sourced sustainably without taking up space for growing food crops or causing deforestation.

There are also some attributes of current cellulose sources which will need to be improved for use in a wide variety of packaging materials.

Many cellulose sources have been explored, but micro-algae is an under-researched area of particular interest due to its many advantages to other forms of cellulosic feedstock, including differentiation in cellulose structure. Proposed solution and methodology

To utilise cellulose for food packaging, it is possible to create regenerated cellulose films. The process occurs by extracting the cellulose from the host species then breaking the bonds between the cellulose polymers. The cellulose polymers can then be reformed into a film by a coagulation medium which allows the cellulose polymers to bond, forming a film.

Micro-algae are species with different cellulose structures that may provide unique properties to the extracted cellulose. The structure in which the cellulose is formed depends on the position of the cellulose synthase complexes (Terminal Complexes). In higher plants, these are arranged in a hexagonal structure called a rosette structure.

In microalgae, they can also be arranged as single rows, multiple rows, or diagonal rows. This difference in structure could impart different physicochemical properties, which would help create bioplastics for varying applications or combine for multiple purposes. Research into algal cellulose and its creation into algal films could therefore provide multiple benefits and help solve the current plastic crisis.

The first phase of experimentation will be to use the model algae Chlorella vulgaris to develop a successful extraction and film formation process that allows for advantageous structural breakdown necessary for film formation whilst retaining some of the original cellulose structure. The second phase will be using diverse algal sources that present the different cellulose synthase complexes and compare the structure and the properties of the films.

The final stage will be to optimise both the extraction process, to limit environmental impact and the properties of the film using algal species. This information can then be used for scaling up the production for use in the real-world practice setting.