# Natural Compounds in the Battle against Microorganisms--Linalool
## 3 Antimicrobial Activity  
Linalool has a known antimicrobial effect against both bacteria and fungi. The list of strains against which it is active is summarized in Table 2. Although it is a component of several plants, i.e., coriander, rosewood, basil, mint, ginger, laurel, thyme, sage, nutmeg or cinnamon, it is poorly used in nutritional systems due to its physical properties: it is poorly soluble in water and has high volatility and low stability. However, due to several proven activities, linalool is a promising ingredient of food. There are many reports in the literature on the antimicrobial properties of linalool; however, especially those that prove that this monoterpene is effective against life-threatening strains, including multi-drug resistant strains, i.e., _E. coli_ O157:H7 [55] or Pseudomonas aeruginosa_[56], deserve attention. In addition, the effective effect of linalool against bacteria associated primarily with gastrointestinal infections (e.g., _Salmonella enterica_ subsp. _enterica_ serovar Typhi, _Salmonella enterica_ subsp. _enterica_ serovar Typhimurium, _E. coli_, _Vibrio fluvialis_, _Campylobacter jejuni_ and _Staphylococcus aureus_) [57; 58; 59], as well as with periodontal diseases and caries (e.g., _Porphylomonas gingivalis_, _Prevotella internedia_, _Prevotella nigrescens_, _Fusobacterium nucleatum_, _Aggregatibacter actonomycetemcomitants_, _Streptococcus mutans_ and _Streptococcus sorinus_) [60] and diseases caused by opportunistic bacteria (_P. aeruginosa_ and _Staphylococcus epidermidis_) [26; 61]. Adding linalool to food would have broadly understood positive effects as it has been shown to be active against microbes contaminating the food: _Campylobacter_ spp. (undercooked poultry, raw milk and contaminated water) and _Salmonella_ spp. (eggs, meat, poultry, milk, and unwashed green fruit and vegetables)) as well as _Listeria monocytogenes_[62] (soft and mature cheeses, raw milk, cream, eggs, ice cream, meat, smoked fish, pork, sausages, raw vegetables and fruits, and frozen foods) and _E. coli_ (unwashed vegetables and fruits, raw meat and water). However, the physical properties of linalool turn out to be a problem, mainly its solubility, stability and sensory properties, as well as its susceptibility to react with factors included in the food, i.e., water, fat, protein, salt and pH. This difficult to overcome barrier related to the bioavailability of this monoterpene in nutritional systems was solved by [PERSON] et al. [61]. In their research, they proved that linalool can be closed in nanoemulsions, colloidal dispersions, which are characterized by high stability. Moreover, such a system shows an order of greater microbial activity against \(S\). Typhimurium ATCC 13311 than pure monoterpene. This is most likely due to the fact that it penetrates better into the bacterial cell. However, despite this, such a system is less effective at reducing the structure of the biofilm. More effective in this case, due to its small size, is pure linalool (effectiveness: linalool nanoparticle; 64.5-56.9%). To increase the antimicrobial activity, to eliminate negative organoleptic effects and to change the natural properties of food after adding the desired concentrations of linalool, it was combined with food ingredients acceptable for consumption, including vitamin C and copper (II) ions. This treatment significantly reduced the MIC values to 32 mM, 7.5 mM and 212 \(\upmu\)M for _V. fluvialis_, _S. enterica_ subsp. _enterica_ serovar Typhi and _E. coli_ ATCC 25922, respectively [57]. A synergistic effect of these compounds was also observed in this combination. A synergistic effect of these compounds was also observed in this combination.