# Natural Compounds in the Battle against Microorganisms--Linalool
## 4 Microbial Biotransformation of Linalool
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Strain** & **Activity of Linalool** & **Referece** \\ \hline _Candida albicans_ NCPF3179 & 12 mm & [63] \\ _Candida albicans_ ATCC 14053 & 8 mM & [73] \\ _Candida glabrata_ (c.s.) & 16 mM & [73] \\ _Candida tropicials_ ATCC 13803 & 125 ug/mL & [74] \\ _Candida tropicials_ (c.s.) & 16 mM & [73] \\ _Trichophytton rubrum_ LM 305 & 256 ug/mL & [67] \\ _Micosporum canis_ (c.s.—LM910, LM82, LM29) & 128 ug/mL & [75] \\ _Micosporum gypseudum_ (c.s.—LM512, LM130) & 128 ug/mL & [75] \\ \hline Legend: c.s.—clinical strain. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Antimicrobial activity of linalool against fungi. In another experiment, _Colletotrichum acutatum_ TQ058A and _C. nymphphaeae_ CBMAI 0864 strains were used for the biotransformation of linalool. Both strains converted linalool to _cis_- and _trans_-furanoid linalool oxide. In the case of the _C. acutatum_ strain, the products were formed in the amount of 0.04 g/L and 0.03 g/L, respectively. In the case of the _C. nymphphaeae_ strain, these values were slightly higher and amounted to 0.05 g/L and 0.04 g/L, respectively was obtained [81]. Not only fungi but also microalgae can convert linalool into cyclic ethers. As a result of a 24 h biotransformation using the microalgae _Oocyststis pusilla_, (3_R_)-(--)-linalool was transformed into a mixture of _trans_-(2\(R\),5_R_)-furanoid linalool oxide with an efficiency of 8% and _trans_-(2\(R\),55)-pyranoid linalool oxide with an efficiency of 6% [82]. On the other hand, when (35)-(+)-linalool was used as a substrate for biotransformation, it turned out that microalgae led to not only double bond epoxidation and subsequent cyclization of linalool but also a reduction in double bonds. Microalgae isolated from rice fields in Iran were immobilized in calcium alginate and incubated with substrate for 24 h. The _Chlorella_ spp. MCCS 028 strain transformed the substrate into a mixture of _cis_-(2\(S\),5_R_)- and _trans_-(2\(S\),5_S_)-furanoid linalool oxide (both with a yield of 1.4%) and into dihydrolionaloid with a yield of 3.2%. On the other hand, the strains of _Chlorella_ spp. MCCS 029 and _Chlamydomonas_ spp. MCCS 036 were only able to reduce linalool to dihydrolinalool, which allowed for 4.1% and 3.3% of this compound to be obtained, respectively [83] (Scheme 3). Some of the tested microorganisms proved to be able to convert linalool into other monoterpencids. Fungi isolated from fruits found in Brazil were used for the biotransformation of (35)-(+)-linalool (Scheme 4). These strains were incubated in YM medium for 72 h, and 0.1% of the substrate was added. The substrate addition was continued every 24 h for the next 3 days. After another 24 h, extraction was performed. One strain, designated LB-2002, was able to convert the substrate to _cis_-(2\(S\),5_R_)- and _trans_-(2\(S\),5_S_)-furanoid linalool oxide, with efficiencies of 65% and 35%, respectively. For the first of these products, the yield was 160 mg/L. Similar products were obtained using the LB-2008 strain isolated from acerola for biotransformation. The LB-2007 strain, isolated from graviola, converted linalool to geraniath a yield of 7 mg/L. The LB-2010 and LB-2050 strains, on the other hand, were able to convert linalool to \(\alpha\)-terpineol with capacities of 150 and 130 mg/L, respectively [84]. The yeast _Saccharomyces cerevisiae_ IWD72 (prototrophic haploid, MATA), _Torulaspora delbrueckii_ NCYC 696 and _Kluyveromyces lactis_ IFO1267 were used to biotransform the racemic mixture of (\(\pm\))-linalool. Twenty-five \(\mathrm{\SIUnitSymbolMicro g/mL}\) of linalool was added to the grown cultures, and the biotransformations were carried out for 72 h. The only product of biotransformation was (\(\pm\))-\(\alpha\)-terpineol. It was obtained with yields of 12.2% for the _S. cerevisiae strain_ and 20.8% for the _T. delbrueckii_ strain. The _K. lactis_ strain, which gave 31.4% of \(\alpha\)-terpineol, turned out to be the most effective [85].