Microalgae as a Renewable Resource for Bioplastic Production

Introduction

With the increasing demand for plastic-based products and the depletion of fossil fuels production, great attention has been focused on finding sustainable resources for the production of bioplastics (Ali et al., 2019; Darwish et al., 2021). Therefore, it is urgent to decrease our reliance on crude oil for plastic production. Moreover, there is a mass need to reduce plastic accumulation in landfills. From 1950 to 2018, the total plastics production reached 8.3 billion metric tons, increasing 5% annually (Geyer et al., 2017; Ali et al., 2021a, b, c, d). At the same time, the annual production of plastics is expected to double by 2035 (800 Mt) and reach 1600 Mt by 2050. After 2020, more than 400 Mt of plastic wastes will be produced annually (Barra & Leonard, 2018). Regrettably, 76% of the overall plastic production is finally handled as wastes. Of these, 9% is recycled, 12% is incinerated, and 79% is landfilled or released to the environment (Geyer et al., 2017). Therefore, the accumulation of plastic waste showed a continuous growth of environmental pollution problems, causing severe impacts on humans and animals (Ali et al., 2021a, c, d). Plastics are classified into four types based on production origin (Fossil-based or Bio-based polymers), as shown in Figure 1 (Reddy et al., 2013).

Imre et al. (2019) define bioplastics as biodegradable and/or derived from renewable sources, making them a viable alternative to fossil-based plastics. Bioplastic output capacity is expected to rise to 2.62 million tons by 2023 (European Bioplastics, 2020a, b). The main motivation of this output growth is the advanced innovative biobased polymeric material such as polybutylene succinate (PBS), polylactic acid (PLA), and polyhydroxyalkanoates (PHA) (European Bioplastics and nova-Institute, 2019a, b, c). However, until today, manufacturing bioplastics is significantly more expensive than those of fossil plastics (Raza et al., 2018; Tsang et al., 2019). On the other hand, using appropriate organic wastes and by-products as raw materials using different microbial strains can overcome bioplastic production costs (Jõgi & Bhat, 2020). The majority of bioplastic materials are derived from crops, and this affects the availability of food resources. Furthermore, this type of bioplastic material requires agricultural land, fertilizers, suitable conditions and water (Zeller et al., 2013). Thus, this cannot be sustained for long-term bioplastic production.

Figure 1.

Plastic classification based on production origin (Reddy et al., 2013).