# Microbial Biopolymers: From Production to Environmental Applications--A Review
## 1 Introduction  
The worldwide population is consistently expanding, necessitating the expansion of the food supply and putting pressure on the limited available natural resources. This shift has ushered the agricultural sector into forming a noteworthy amount of waste. The environment is frequently being polluted due to rapid industrialization and the shift of populations to urban areas, leading to several concerns such as water pollution, waste expulsion in the surroundings, and environmental deprivation [1, 2].  
Faced with this significant increase in the global population, modern agriculture is proving to be an advantageous solution since it offers the opportunity to upsurge crop yield. However, it also led to an increase in the global carbon footprint, and the generation of waste from farming impacts the economic and social sectors. As per [3], agriculture comprises around 38% of the terrestrial surface area on Earth. The Food and Agricultural Organization (FAO) stated that the amount of food wasted annually during farming, post-harvesting, and agriculture processing was 1.3 billion tons [4]. The utilization of agricultural residues and their transformation into biopolymers presents a great opportunity to reduce the global carbon footprint, considering that the landfilling of residue promotes global warming.  
The increasing concern for diverse environmental problems has led to the development of new approaches to diminish its deteriorated effects. Amidst various approaches,the formation of microbial biopolymers is a method that has earned great engagement due to its superiority over synthetic biopolymers in terms of sustainability, biodegradability, cost-effectiveness, structural diversity, non-toxicity nature, and bioactivity. This is due to a customized range of functional groups with defined molecular weights. Biodegradability relies on its chemical network so that it can be debased by biological attack. Moreover, the approach to the degradation of biopolymers relies on factors such as dampness, temperature, and pH. However, various functional, thermal, morphological, and rheological tests are usually executed to check its capability [5].  
Nowadays, many synthetic polymers are more admissible and have become a regular part of our lives, including dyes, Teflon, plastic polyester, etc. Biopolymers are described as a considerable group of molecules separated from their cell walls and based on repeated functional units at a specific level. Microbes are cell-forming manufactories that can transform carbon and nitrogen into extensive amounts of extracellular, intracellular, and capsular biopolymers. Based on chemical configurations, microbial biopolymers are classified into polyphosphates, nucleotides, polysaccharides, polyamides, and polyesters. Among all polyesters, biopolymers are widely adequate and are manufactured through metabolic pathways [6]. Some microbial biopolymers have drawbacks such as poor functional and mechanical attributes and sensitivity towards chemicals; these can be mitigated by developing hybrids or nanobiocomposites using nanofillers.  
Many researchers have recently concentrated on the utilization of biopolymers and their potential as biomaterials. Microbial biopolymers have applications in the food, textile, agriculture, and pharmaceutical industries due to their unique characteristics. Environmental applications of microbial biopolymers have grown in popularity during the last decade. Biopolymers could be generated in large quantities for cutting-edge applications such as biofilm matrices, bio-flocculants, heavy metal adsorption, bioremediation, etc. [7; 8; 9; 10]. This review focuses on microbial biopolymers, their classifications and characteristics, the factors influencing their production, and their emerging environmental applications.