Análise da eficiência de diferentes métodos físicos de lise celular na extração de proteínas solúveis da microalga Botryococcus sp.

Abstract

Microalgae are versatile microscopic beings. They have the capacity to produce biocompounds such as proteins, lipids, carbohydrates and dyes on an industrial scale. Thus, many species have been exploited by different industrial sectors, given their diverse applications. Microalgae of the genus Botryococcus are considered promising sources for the production of lipids, but studies that explore their capacity as a source of proteins are still incipient. The objective of the present study was to evaluate the efficiency of different physical methods of cell lysis in the extraction of soluble proteins from the microalgae Botryococcus sp. grown in a closed photobioreactor. Initially, the microalgae were cultivated in Bold's Basal Medium (BBM) in a rectangular plate photobioreactor for 21 days under controlled conditions. The microalgal biomass produced was counted, processed and subjected to elemental analysis. Different physical methods of cell lysis (homogenizer with glass beads, maceration, ultrasonication and freeze/thaw) were used (in isolation or in combination) to produce seven crude extracts (EBs). These EBs were evaluated by the Bradford assay to quantify soluble proteins, followed by electrophoretic analysis (SDS-PAGE) to evaluate the protein profiles of the extracts. As a result, the cultivation conditions allowed an average yield of 5.12 + 0.03 g of biomass per liter of culture, with emphasis on the total protein (26.07%) and lipid (35.82%) content. The cell disruption method that demonstrated the most efficient extraction was the combination of freezing and thawing, maceration and ultrasonication techniques, which resulted in the recovery of 7.26 mg of total soluble proteins. The protein profiles of EBs observed by SDS-PAGE showed the same pattern of protein bands. However, EBs obtained by more efficient methods, presented protein profiles with higher resolution and more intense bands. Finally, this brief study reinforced the importance of validating an appropriate lysis method for the analyzed cell model, especially when the biocompounds of interest are proteins.