Abstract
Different molecules have been tested as analog receptors due to their capacity to bind bacteria and prevent cell adhesion. By using in vitro assays, the present study characterized the aqueous and alkaline extracts from microalgae Pavlova lutheri and Pavlova gyrans and evaluated the capacity of these extracts to adhere to enterobacteria (Salmonella Typhimurium). The aqueous and alkaline extracts of both species were fractionated via freeze-thawing, giving rise to soluble and insoluble (precipitate) fractions in cold water. The obtained fractions were studied using thermogravimetric, methylation analyses, and using 1D and 2D NMR techniques. The cold-water-soluble fractions obtained from the aqueous extracts were mainly composed of highly branched (1→3),(1→6)-β-glucans, whereas the cold-water-precipitate fractions were constituted by (1→3)-β-glucans. The alkaline extract fractions showed similar compositions with a high protein content, and the presence of glycosides (sulfoquinovosylglycerol (SQG), digalactosylglycerol (DGG)), and free fatty acids. The linear (1→3)-β-glucans and the alkaline extract fractions showed an adhesion capacity toward Salmonella. The chemical composition of the active fractions suggested that the presence of three-linked β-glucose units, as well as microalgal proteins and glycosides, could be important in the adhesion process. Therefore, these microalgal species possess a high potential to serve as a source of anti-adhesive compounds.
Highlights
Microalgae are photosynthetic microorganisms capable of producing a wide variety of biomolecules in accordance with the division or class to which they belong
Dried biomasses of P. gyrans and P. lutheri were extracted under sequential aqueous extraction followed by alkaline extraction
GW-p (0.9%), GW-s (3.8%), GA-p (1.2%), and GA-s (0.4%) from P. gyrans, and LW-p (0.6%), LW-s (4.7%), LA-p (1.0%), and LA-s (0.9%) from P. lutheri (Figure 1) (G and L fractions correspond to P. gyrans and P. lutheri, respectively; W and A correspond to aqueous and alkaline extracts, respectively; and p and s correspond to precipitated and supernatant extracts, respectively)
Summary
Microalgae are photosynthetic microorganisms capable of producing a wide variety of biomolecules in accordance with the division or class to which they belong. Phylum Haptophyta comprises two classes, Coccolithophyceae and Pavlovophyceae [4], where the latter includes the two marine species under study, Pavlova lutheri and Pavlova gyrans. Since they can be grown, quickly ingested and digested, and exhibit a high nutritional value, these species, as well as some other microalgae, are widely used as raw material in the aquaculture of fish, mollusks, and crustaceans [5,6,7].
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