# Microbial Application to Improve Olive Mill Wastewater Phenolic Extracts
## 2 Results
### Bioconversion Efficiency by W. anomalous and L. plantarum  
In the bioconversion test, the two microorganisms showing the best performances at the enzymatic tests (Table 3) were used to evaluate their ability to increase the HT and TY concentrations in the OMW extract. The SP207 extract was used as substrate for both pellets and filtered supernatants. The kinetic analysis of bioconversion was done through HPLC quantification of single phenols up to 6 h. The treatment with the commercial enzyme highlighted a slow and constant increasing of both HT and TY, whereas the treatment with the two tested microorganisms showed the highest value of phenols, reaching the plateau after 2 h of reaction. The only exception was detected after 6 h in the sample treated with pellets, when a further increase of HT value was registered (Table S1, on-line Supplementary Materials). Overall, the highest phenolic values were obtained using the microbial pellets rather than the filtered broths. The mean values of HT, TY, and OLE obtained after 2 h are shown in Figure 2. The highest values of HT were reached using _W. anomalous_ and _L. plantarum_ pellets (+35.5% and +33.7%, respectively), whereas no statistical difference between the control sample and the _W. anomalous_ broth was observed. The TY content increased significantly only after contact with both pellets (+32%). Regarding the OLE amount, although a decrease was registered after 2 h by using the commercial enzyme, its concentration remained almost constant up to 6 h (Table S1). On the contrary, the OLE concentration increased in the presence of both strains' pellet (+30.2% and +29.5%) and to a lesser degree with _W. anomalous_ broth (+7%).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Assorbent Resin** & **Hydroxyprosol (HT)** & **Tyrosol (TY)** & **Oleuropein (OLE)** & **Total Phenols** \\ \hline SP207 & 3239.7 \(\pm\) 57.34 a & 2016.8 \(\pm\) 49.36 a & 11,336.6 \(\pm\) 199.65 a & 16,447.9 \(\pm\) 16.31 a \\ XAD16 & 1381.7 \(\pm\) 66.45 b & 1000.3 \(\pm\) 120.75 b & 10,047.8 \(\pm\) 120.29 ab & 13,144.6 \(\pm\) 21.75 b \\ PAD900C & 294.3 \(\pm\) 2.67 c & 90.0 \(\pm\) 10.59 c & 4443.8 \(\pm\) 176.32 c & 4880.3 \(\pm\) 10.87 d \\ C18 & 191.1 \(\pm\) 16.59 c & 50.4 \(\pm\) 10.34 c & 8092.3 \(\pm\) 218.15 b & 8763.6 \(\pm\) 43.50 c \\ \hline \hline \end{tabular} Data are expressed as mg/L of means \(\pm\) standard deviations. Different letters indicate statistical differences within the same column (Significance at \(p<\) 0.001).  
\end{table}
Table 2: Phenols detected in OMW extracts obtained with the different tested resins.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Samples** & **Beta-Glucosidase** & **Esterase** \\ \hline Lallzyme beta enzyme & 6979.9 \(\pm\) 3.22 b & 316,713.9 \(\pm\) 1032.48 c \\ _W. anomalous_ & 7066.4 \(\pm\) 5.36 b & 405,417.6 \(\pm\) 516.24 b \\ _L. plantarum_ & 2387.6 \(\pm\) 3.22 c & 316,348.9 \(\pm\) 1540.62 c \\ _S. cerevisiae_ & 1437.9 \(\pm\) 78.31 d & 399,577.0 \(\pm\) 1548.72 b \\ _A. niger_ & 314,313.8 \(\pm\) 107.28 a & 4,506,229.2 \(\pm\) 4646.15 a \\ \hline \hline \end{tabular} Data are expressed as IU/mL of broth sample (means \(\pm\) standard deviations). Different letters indicate statistical differences within the same column (Significance at \(p<\) 0.001).  
\end{table}
Table 3: Beta-glucosidase and esterase activities detected for the commercial enzyme and the different microorganisms tested under their specific growth culture conditions.