The microalgae Chlorella vulgaris is a potential source of biomass and several biopolymers. The aim of this study was to evaluate the production of polyhydroxyalkanoate and the formation of plastic film under constant light stress (24h) and photoperiod (12/12h – light/dark), in addition to the influence of inorganic nitrogen source deficiency (NaNO3 – 50%), under cell concentration (Xm), productivity (PX) and specific growth rate (µ). The polymer was also characterized by Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TGA). Autotrophic conditions (CBBM24) under constant light stress (24h) showed better results, with Xm = 1163.45 ± 52 mg L-1, PX = 145.43 ± 7 mg L-1 day-1 and µ = 0.39 ± 0.00 day-1 during 8 days of cultivation. After extraction, the polymer obtained was characterized by FTIR, showing transmittance bands located at 1722 cm-1 that were attributed to the stretching vibration of the C=O group (carbonyl ester) in the PHA polyester. Thermal analysis (TGA) showed that the polymer obtained from CBBM24 biomass showed Tonset (21%) at 91 °C and Tdecomp (76%) at 295 °C. The plastic film was also produced using glycerol plasticizer, thus demonstrating that microalgae has strong potential in the production of biodegradable plastic.

Polyhydroxyalkanoates (PHA) are a family of intracellular biopolymers biodegradability and biocompatibility produced by numerous bacteria. The search for new PHA-producing microorganisms is crucial for expanding bioplastic production, as seen with Brevibacterium sp. In this study, hydrolysates of Spondias mombin peels were used as a carbon source for PHA synthesis through the fermentation of Brevibacterium sp. This process contributes to the bioeconomy by producing biodegradable plastic from waste materials that would otherwise be discarded. For morphological characterization of the bacterial isolate, optical microscopy, scanning electron microscopy, and transmission electron microscopy analyses were performed. Molecular identification was ensured by analysis of the 16S rRNA gene. The biopolymer was characterized by infrared spectroscopy, thermal analysis, and scanning electron microscopy. The polyhydroxybutyrate produced by Brevibacterium sp. showed characteristic infrared stretching. The Spondias mombin pells was efficient carbon sources for PHA production from the biosynthesis of a bacterium for bioplastic production: Brevibacterium sp. Here is the first report, to our knowledge, on the production of PHA from cajá peel (a fruit typical of the northern and northeastern regions of Brazil) using Brevibacterium sp. as the biopolymer producer.