## 3 Results and Discussion
The above analysis shows that the hydroxylactone **5** obtained during the biotransformation presented here is analogous to the hydroxylactone obtained earlier from iodolactone **4** by [PERSON] et al. (2017). It is important to notice that hydroxylactone **5** obtained during biotransformation was structurally different to its analog obtained synthetically ([PERSON], 1998). It was ascertained based on the comparison between \({}^{1}\)H NMR spectra of both compounds. The main difference was the shape and position of signals coming from the protons H-1 and H-2. In the obtained microbiological hydroxylactone **5** signal coming from proton H-2 lying at 3.75 ppm there was a doublet of doublet of doublet, while the signal of proton H-1 was a triplet lying at 4.58 ppm. In the above cited synthetic hydroxylactone only one narrow multiplet coming from protons H-2 and H-1 lying at 4.27 ppm was observed. These differences were the consequence of the different position of a hydroxy group. In hydroxylactone **5** obtained by biotransformation, a hydroxy group was situated in an equatorial position, while in hydroxylactone obtained by chemical synthesis, it was situated in an axial one. Unfortunately, we were not able to obtain hydroxylactone **5** with such high yield as described in the abovementioned article. However, use of bromolactone **3** for biotransformation gave hydroxylactone **5** with a small (17.7%) enantiomeric excess. As it is known, the different bicyclic lactones were often endowed with interesting biological properties such as antifeedant activity against storage pests, Colorado potato beetle, and aphids ([PERSON], 1991; [PERSON], 1992; [PERSON], 1993) or the inhibition of the growth of some microorganisms ([PERSON], 1992; [PERSON], 1993; [PERSON], 1998). Knowing that, the lactones presented here were tested in this respect. Halolactones **2-4** and hydroxylactone **5** were examined for their ability to inhibit the growth of some bacteria, yeast and fungal strains. The highest activity against the tested microorganisms showed bromolactone **3** and iodolactone **4**. The smallest one was the product of biotransformation--hydroxylactone **5**. The results of these tests are presented in Figures 2-7. Of the tested bacteria strains, the highest sensitivity was demonstrated by the _S. aureus_ strain. Its growth was completely inhibited by lactones **2-4**. Also, lactone **5** showed a negative impact on the growth of this strain causing a significant extension of the adaptive phase (20-36 h) and a small increase in biomass expressed as \(\Delta\)OD in the range 0.36-0.62. Also, filamentous fungi proved to be susceptible to the microbial activity of some test compounds. Lactones **3** and **4** completely inhibited the growth of the _F. linii_ strain, and significantly limited the expansion of the _A. niger_ strain. Fungi strains proved to be insensitive to the activity of lactone **5**. This compound even stimulated the growth of the fungus _F. linii_, resulting in a greater increase in biomass of about 0.58, as compared to the control culture. Figure 1: Structure of lactones **2–5**. Figure 4: The assessment of the effects of the lactones **2**–**5** on the growth of _A. niger._ (OD-Optical Density was measured for \(\lambda\) 550 nm). Figure 3: The assessment of the effects of the lactones **2**–**5** on the growth of _F. linii._ (OD-Optical Density was measured for \(\lambda\) 550 nm). Figure 2: The assessment of the effects of the lactones **2**–**5** on the growth of _S. aureus._ (OD-Optical Density was measured for \(\lambda\) 550 nm). Figure 5: The assessment of the effects of the lactones **2–5** on the growth of _E. coli._ (OD-Optical Density was measured for \(\lambda\) 550 nm). Figure 6: The assessment of the effects of the lactones **2–5** on the growth of _P. fluorescens_ (OD-Optical Density was measured for \(\lambda\) 550 nm). Figure 7: The assessment of the effects of the lactones **2–5** on the growth of _C. albicans_ (OD-Optical Density was measured for \(\lambda\) 550 nm).