## 4 Biosynthesis of Dextran in Optimized Microbial Processes
### Dextran Synthesized by Specific Strains of a Few Weissella Species  
_Weissella_ genus was earlier considered to be a member of the Leuconstocaceae family, but later it was placed in Lactobacillusaceae. _Weissella confusa_ was formerly known as _Lactobacillus confusus_ as it resembles in numerous properties with other _Lactobacillus_ bacteria. Hence, it has often been mistaken for bacteria of the _Leuconstoc_ and _Pediococcus_. It is a non-motile coccus Gram-positive, catalase-negative, facultative anaerobic with an efficient fermentative metabolism. Although there are about 22 known species of _Weissella_, _W. confusa_ has been generally employed in fermentation for its utilities (Table 4). The studies for dextran synthesis mainly employed two species of _Weissella_, namely _confusa_ and _ciberia_; some relevant references have been summarized in Table 4. \begin{table}
\begin{tabular}{c c c c} \hline
**Dextran Product** & **Substrate/s Used in Biosynthesis** &
\begin{tabular}{c} **Strains Used to Conduct** \\ **Fertentative-Production** \\ \end{tabular} & **Reference** \\ \hline
94\% of \(\alpha\)-(1\(\rightarrow\)6) 06\% of \(\alpha\)-(1\(\rightarrow\)3) & 10\%, \(w/v\) solution of sucrose &
\begin{tabular}{c} _L. mesenteroides_ strain SF2 \\ an isolate from _Agare salimina_ \\ \end{tabular} & [74] \\ \hline
74\% of \(\alpha\)-(1\(\rightarrow\)6) 26\% of \(\alpha\)-(1\(\rightarrow\)3) & 10\%, \(w/v\) solution of sucrose &
\begin{tabular}{c} _L. mesenteroides_ strain SF3 \\ an isolate from _Agare salimina_ \\ \end{tabular} & [74] \\ \hline
970 kDa &
\begin{tabular}{c} _L. mesenteroides_ strain UCT/L18 \\ an isolate from fermented rice batter \\ \end{tabular} & [79] \\ \(\alpha\)-(1\(\rightarrow\)3) & & & \\ \hline
52\% of \(\alpha\)-(1\(\rightarrow\)6) 48\% of \(\alpha\)-(1\(\rightarrow\)3) & Solution of 10\% sucrose with 5\% maltose & _L. mesenteroides strain_ NRRL B-1149 & [80] \\ \hline
10–40 MDa & 10\%, \(w/v\) solution of sucrose &
\begin{tabular}{c} _L. mesenteroides_ strain AA1 \\ an isolate from fermented cabbage \\ \end{tabular} & [61] \\ \hline
960 MDa & Solution of 15\%, \(w/v\) sucrose with pineapple juice & _L. mesenteroides_ strain ATCC 10830 & [81] \\ \hline
635 kDa 94\% of \(\alpha\)-(1\(\rightarrow\)6) 60\% of \(\alpha\)-(1\(\rightarrow\)3) & Solution of 15\%, \(w/v\) sucrose with tomato juice & _L. mesenteroides_ strain BD1710 & [82] \\ \hline
25–40 MDa &
\begin{tabular}{c} _L. mesenteroides_ strain KIBGEIB22M20 \\ \end{tabular} & [73] \\ with \(\alpha\)-(1\(\rightarrow\)3) & & & \\ \hline
15–20 MDa &
\begin{tabular}{c} _L. mesenteroides_ strain KIBGE-IB22 \\ \end{tabular} & [73] \\ with \(\alpha\)-(1\(\rightarrow\)6) 48\(\rightarrow\)(1\(\rightarrow\)3) & 10\%, \(w/v\) solution of sucrose & _L. mesenteroides_ strain KIBGE-IB22 & [73] \\ \(\beta\)-(2\(\rightarrow\)6) & & & \\ \hline
93\% of \(\alpha\)-(1\(\rightarrow\)6) 07\% of \(\alpha\)-(1\(\rightarrow\)3) & Solution of 5\%, \(w/v\) sucrose with whey & _L. mesenteroides_ strain BA08 & [83] \\ \hline
230 MDa & \
\begin{tabular}{c} _L. mesenteroides_ strains \\ CM9, an isolate from camel milk, \\ CM30, an isolate from camel milk, \\ KIF10, an isolate from meat, \\ SM34, an isolate from sheep milk \\ \end{tabular} & [84] \\ \hline n.d. &
\begin{tabular}{c} Solutions of \\ 2-10\% whey with molasses; \\ 6\% cheese-wheey \\ \end{tabular} & _L. mesenteroides_ strain NRRL B512 & [85] \\ \hline \(<\)40 kDa & 3\%, \(w/v\) solution of sucrose & _L. mesenteroides_ strain NRRL B512 & [86] \\ \hline \(<\)10 kDa & 5\% milk permeate & _L. mesenteroides_ strain NRRL B512 & [86] \\ \hline \end{tabular}
\end{table} 
Table 2: Cont.