## 1 Introduction  
The worldwide environmental concern impacts every aspect of our lives, food packaging included. Due to the rapid growth of the global population and changing lifestyle, food packaging significance increased exponentially together with the innovation pressure for developing ecofriendly solutions. Thus, a new generation of packaging materials developed from underused secondary industrial food by-products is in the pipeline striving to achieve high functionality, eco-efficiency, and, moreover, sustainability. The next generation of food packaging should be based on green solutions (UN's Sustainable Development Goal 12) and be able to interplay reduction in the amount of petroleum-based packaging to minimize environmental harm, food waste, and food by-products with food quality and safety [1]. Among easily renewable raw materials and/or secondary food industry products, several possibilities were studied recently to evaluate the potential of sustainable food packaging based on biodegradable polymers such as polylactic acid, microbial polyesters, or bacterial cellulose [2, 3]. Edible coatings or films are sustainable food packaging solutions which can be obtained from vegetal or animal polysaccharides, proteins, lipids, or their mix resulting in composite packaging materials [4]. Their ability to act as carriers for bioactive substances, like antimicrobials, antioxidants, probiotics, or nutraceuticalals, and compatibility with food matrix renders them a wide array of food applications. The encapsulation of bioactivesubstances ensures their protection from environmental factors like pH or temperature during processing, or their prolonged release during food storage or consumption, depending on the application [5]. Nevertheless, biopolymeric packaging applications from vegetal or animal resources are hindered by the limitations of these resources and by several properties that need improvement in order to reduce the gap between the properties of petroleum-based and biodegradable food packaging materials. For example, the improvement of biopolymer-based food packaging's poor mechanical resistance, high permeability to water vapors or oxygen, would speed up their industrial applications [6]. For example, low density polyethylene has tensile strength ranging 8-25 MPa and water vapor permeability of 0.004-0.006 g mm/m\({}^{2}\)-d\(\cdot\)kPa [7; 8], while for whey protein films, for example, the respective values are approx. 4 MPa and 5-7 g\(\cdot\)mm/d\(\cdot\)m\({}^{2}\cdot\)kPa [8] and for yeast cell films 0.7-3.1 MPa [9] and 0.47-27.7 \(\times\) 10\({}^{-10}\) g\(\cdot\)s\({}^{1}\cdot\)m\({}^{-1}\cdot\)Pa\({}^{-1}\)[10]. To surpass these limitations, grafting compounds into a biopolymeric matrix could be a promising improvement strategy. Sugarcane bagasse and other lignocellulosic materials have been used as reinforcing fillers in whey protein films [11]; bio composite active packaging based on chitosan and \(\beta\)-cyclodextrinrin [12] and other bio composite matrices [13] confer a significant impact primarily on mechanical strength and water vapor permeability. However, vegetal cellulose has the disadvantage of low thermal stability [8]. One of the most promising sources of biopolymers is microbial biomass which could meet the promise of cheap applications based on circular economy principles, using agricultural and food waste for the production of resilient food packaging while enabling the food packaging industry to decouple from fossil stocks and return nutrients to the soil. Edible films and coatings can be obtained from both the baker or brewing yeast belonging to the same genus, _Saccharomyces_. However, the mechanical properties and the water vapor permeability of these materials still needs to be improved, for example, for yeast cell films tensile strength of 0.7-3.1 MPa [9] and 0.47-27.7 10\({}^{-10}\) g\(\cdot\)s\({}^{-1}\cdot\)m\({}^{-1}\cdot\)Pa\({}^{-1}\)[10] were reported.