Potencialidades biotecnológicas de consórcio de microalgas cultivadas em efluente de biodigestor

Abstract

Microalgae are photosynthetic microorganisms found in aquatic (fresh and marine) and terrestrial environments, known for their ability to synthesize a variety of bioactives that arouse interest in their exploitation. The residues generated in agro-industrial processes have high levels of C, N, P and some toxic components that require a treatment step before their disposal in order to avoid compromising ecosystems. Microalgae have the ability to act as bioremediation agents of these residues, in addition, the biomass generated at the end of the process can be destined for some biotechnological application. The present study aimed to carry out a systematic review of the literature on the main occurrences and applications of microalgae consortia; as well as to investigate the potential of the intercropped biomass of microalgae cultivated in different alternative media, the remediation potential of the consortium in the alternative medium and the biochemical composition of the biomass produced, for this we sought to carry out the cultivation of two types of consortium (C5 and C10): five (Monoraphidium litorale, Ankistrodesmus densus, Scenedesmus quadricauda, Pediastrum tetras e Scenedesmus quadricauda) and ten strains of microalgae (Monoraphidium littorale, Chlamydomonas sp., Ankistrodesmus densus, Scenedesmus quadricauda, Pediastrum tetras, Neochloris pseudoestigmata, Scenedesmus communis, Coelastrum microporum, Scenedesmus quadricauda e Pandorina cf morum) all from the microalgae culture bank of LARBIM/UFPB. The cultures were developed in synthetic (WC) and alternative media: poultry biofertilizer (BA), swine biofertilizer (BS) and poultry+swine biofertilizer (BSA) in three different dilutions (1%, 2% and 4%). all in triplicate under controlled conditions of light and temperature, with a photoperiod of 12 hours. Culture development was monitored by in vivo fluorescence within 48 hours for a period of 15 days. The results of the systematic review reveal that studies on microalgae consortium have gained prominence in recent years. The role of consortia in the treatment of effluents and the improvement of microalgal biomass in the quantification of bioactives of interest was highlighted as a recurring theme in the literature. The CBA 4% medium was considered the best medium for the development of the 713.3 mg/L (Consortium of 10 strains - CE10) and 666.7 g/mL (Consortium of 5 strains - CE5) consortia. Removal rates were determined for the selected medium, the biochemical compositions and the profile of fatty acid methyl esters. CE5 was more efficient in removing ammonia (91.6%) and phosphorus (39.45%). The consortia in alternative medium showed high levels of protein (41.08 – 58.23 g/100g). For carbohydrates, the maximum values obtained were for CE5 (16.35 ± 1.57 g/100g) and CS5 (12.73 ± 0.86 g/100g). The fatty acid profiles showed high levels of α-linolenic acid in the alternative media while for oleic acid the predominance was for the consortia in synthetic media. Thermal stability was evaluated for the consortium of five strains (C5) in relation to strains grown in monocultures. The thermal curves showed three events showing that the bioactive compounds start the degradation process at a temperature higher than 185 °C. The results demonstrated the viability of the consortium being cultivated in an alternative medium associated with the production of compounds in the obtained biomass.