## 3 Results
### Growth of L boronitolerans MH2  
The growth profile of the isolated _L. boronitolerans_ MH2 strain bacteria was examined in fixed time intervals. The growth profile exhibiting the lag, exponential, stationary, and decline phase as it was expected. The growth of the bacteria by measuring through light absorbance of the solutions measured at 680 nm (A\({}_{680\text{nm}}\)) by using a JENWAY, 6300 ultraviolet (UV)-visible spectrophotometer at every 6 h. The measured values for the growth of MH2 were recorded based on 10 mm of the TCA-enriched medium. In the lag phase, the bacterium growth was very little because the bacterium does not immediately adapt to the growth condition and the carbon source which was toxic to the bacteria. In the exponential phase, the growth rate of the MH2 bacterium increased. At the end of the exponential phase, the growth curve reached its maximum rate at 96 h. After a long exponential phase, the growth curve reached a stationary phase and then the bacterium enters the decline phase. The growth profile shows that MH2 was able to grow in minimal medium containing 10 mm of TCA. According to [PERSON] et al. [51], the bacterium absorbs TCA from the compound as the sole carbon source and releases chloride ions. The liberated chloride ion during the metabolism of MH2 strain was monitored by a halide ion assay order as an indicator of TCA degradation in the medium [51].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Step** & **Temperature** & **Time** & **Cycles** \\ \hline Initial & 94 °C & 5 min & 1 \\ Denaturation & 94 °C & 1 min & \\ Annealing & 55 °C & 1 min & 30 \\ Elongation & 72 °C & 4 min & \\ Final Elongation & 72 °C & 10 min & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Thermocycling conditions for polymerase chain reaction (PCR) amplification.  
The results of chloride ion released and the growth curve of the bacterium was plotted as shown in Figure 1.  
Figure 1 shows that both the halide ion assay and growth curves of the bacterium in minimal medium exhibited identical trends indicating that the concentration of the released chloride ion and the growth are directly related to each other. The curves for halide ion assay and growth of MH2 were in contrast with the control experiment. The concentration of the chloride ion in the cultivation solution was determined by converting absorbance corresponding to the concentration using the standard curve. The standard curve was constructed using NaCl as a typical standard for measuring soluble chloride concentration [61]. Doubling time of the bacteria in 10 mm TCA-enriched minimal medium was estimated to be 32 h.  
Enzyme Activity in Cell-Free Extracts from Cell Growth in Trichoroacetic Acid (TCA) Medium and Nutrient Broth  
Dehalogenase activity in cell-free extracts was assessed by the release of free halide in an enzyme-substrate reaction in vitro. Cell-free extracts from strain MH2 grown on 10 mm TCA medium as the sole carbon source was prepared. Halide liberation was measured from extracts of cells grown in TCA using TCA as a substrate. However, no halide was liberated by extracts of the same bacteria grown in nutrient broth. This suggests that in nutrient broth no expression of the bacterial dehalogenase gene takes place. The enzyme specific activity of the dehalogenase for TCA was \(1.1\pm 0.05\)\(\upmu\)molCl\({}^{-}\)min\({}^{-1}\).mg\({}^{-1}\) protein.