# Marine microalgae Biomolecules and Their Adhesion Capacity to _Salmonella enterica_ sv. Typhimurium
## 3 Results  
### Extraction and Characterization of Polysaccharides from P. gyrans and P. lutheri  
Dried biomasses of _P. gyrans_ and _P. lutheri_ were extracted under sequential aqueous extraction followed by alkaline extraction. Crude aqueous and alkaline extracts were treated with EtOH, and ethanolic precipitates were submitted to freeze-thawing and dialysis, producing the fractions 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). Table 1 shows the chemical analyses and monosaccharide compositions of these fractions. The aqueous fractions from _P. gyrans_ (GW-p, GW-s) and _P. lutheri_ (LW-p, LW-s) showed a high content of carbohydrates, with contents varying from 55.6% in LW-p to 83.5% in GW-p. These fractions were mainly constituted by glucose (85.4-100 mol%), indicating the presence of glucans. The alkaline fractions (GA-p, GA-s, LA-p, LA-s) were predominantly composed of proteins, with contents varying from 30.0% in GA-p to 49.1% in LA-p. The carbohydrate contents varied from 11.6% in GA-p to 17.5% in LA-s, and the monosaccharide analysis indicated three main sugars: glucose, galactose, and mannose. Other monosaccharides were present in lower amounts in these fractions. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Fraction**} & **Carbohydrate** & **Protein** & \multicolumn{8}{c}{**Monosaccharides (mol\%)**} \\ \cline{3-10}  & **(\%)** & **(\%)** & **Rha** & **Fuc** & **Ara** & **Xyl** & **Man** & **Gal** & **Glc** \\ \hline \multicolumn{10}{c}{_P. gyrans_} \\ GW-p & 83.5 & 10.7 & tr & tr & tr & tr & tr & tr & 100 \\ GW-s & 68.6 & 18.1 & 1.4 & 1.2 & 1.1 & tr & 2.8 & 2.7 & 90.8 \\ GA-p & 11.6 & 30.0 & 5.2 & 6.5 & 3.7 & 10.6 & 21.6 & 16.0 & 36.4 \\ GA-s & 15.3 & 38.4 & 4.1 & 6.6 & 8.9 & 11.5 & 12.2 & 24.2 & 32.5 \\ \hline \multicolumn{10}{c}{_P. lutheri_} \\ LW-p & 55.6 & 14.5 & 2.1 & 2.5 & tr & tr & 1.5 & 2.0 & 91.8 \\ LW-s & 59.9 & 17.9 & 1.4 & 3.7 & 1.8 & tr & 3.4 & 4.3 & 85.4 \\ LA-p & 15.2 & 49.1 & 8.3 & 7.8 & 3.0 & 5.1 & 14.2 & 17.6 & 44.0 \\ LA-s & 17.5 & 34.7 & 5.5 & 7.7 & 8.2 & 8.1 & 15.4 & 24.9 & 30.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical analyses and monosaccharide composition of fractions from _P. gyrans_ and _P. lutheri_. Thermogravimetric analyses were performed to complement the chemical composition of the microalgal fractions. Thermogravimetric (TG) curves, derivative thermogravimetric (DTG) curves, and characteristics of the microalgal extracts in the TGA process are shown in Table 2 and Figure 2. Although the fractions have different chemical compositions, three stages could be identified for all microalgal fractions that were similar to the previously published works [33; 34]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Fraction**} & \multicolumn{3}{c}{**Total Volatile Matter Content (\%) a**} & \multirow{2}{*}{**Ash and Fixed Carbon (\%) b**} \\ \cline{2-2} \cline{4-5}  & **Stage 1** & & **Stage 2** & **Stage 3** \\ \hline \multicolumn{5}{c}{_P. gyrans_} \\ GW-p & 9.2 & 78.7 & 5.5 & 6.5 \\ GW-s & 7.0 & 66.1 & 16.8 & 10.1 \\ GA-p & 8.8 & 63.6 & 17.4 & 10.1 \\ GA-s & 8.6 & 58.0 & 22.5 & 10.8 \\ \hline \multicolumn{5}{c}{_P. lutheri_} \\ LW-p & 4.6 & 72.8 & 12.3 & 10.3 \\ LW-s & 10.1 & 55.6 & 17.8 & 16.5 \\ LA-p & 10.0 & 64.7 & 18.1 & 7.1 \\ LA-s & 8.3 & 56.1 & 15.4 & 20.1 \\ \hline \hline \end{tabular}  
* Stage 1: Range from 20 to 150 \({}^{\circ}\)C; Stage 2: Range from 150 to 500 \({}^{\circ}\)C; Stage 3: Range from 500 to 800 \({}^{\circ}\)C. b  
Non-degradable residue at 800 \({}^{\circ}\)C.  
\end{table}