**Conflict of interest**

*Bacterial Biofilms*

**7.3 Essential oils**

Naturally plant-derived volatile substances are called as essential oils (EOs). Because of their antibacterial and preservative properties, these are effective and favorable natural products for the food industry. These essential oils are commonly used against a wide diversity of microorganisms since ancient time. These oils exhibit antimicrobial impact on the cell wall of microbes, leading to the destruction of microbes. Furthermore, it is suggested that these oils are very effective in inactivating many microbes without producing antimicrobial resistance [45]. Because of little mammalian toxicity, rapid degradation in the environment and availability of

*Cumin oil* scientifically named *Cuminum cyminum,* a derivative of an aromatic, therapeutic plant of "Apiaceae" family, has various medicinal properties and in the digestive system, it acts as an astringent. It has been widely used for acute gastric diseases as a carminative and eupeptic, and as an analgesic. It is also widely used to flavor foods, for example, added in food for fragrance. Cumin seeds have been used since ancient time. The efficiency of cumin seed against biofilm development on *Klebsiella pneumoniae* strains was observed, which showed that cumin seeds has

*Cinnamon oil* is derived from the inner bark of the "*Cinnamomum zeylanicum'* as well as "*Cinnamomum cassia*" and is mostly used in the food industry due to its specific fragrance [48]. It is suggested that this oil is efficient against biofilm cultures *Lactobacillus plantarum, S. mutans*, and *S. epidermidis*. *Oregano* also is known as *Origanum vulgare* has inhibitory activity on biofilm production in case of *E. coli* and *Staphylococci.* A study revealed that Oregano essential oil exerts antimicrobial action on *E. coli, S. haemolyticus, S. sciuri, S. aureus,* and *S. lugdunensis* and could prevent biofilm formation. Moreover, it also able to detach active biofilm even at very low MIC. Inhibitory activity of *"Brazil nut oil*" named as *Bertholletia excelsa* (a vegetable oil) on commercially available dentifrice to prevent dental biofilm was also assessed. Scientists showed that by adding this vegetable oil to commercially available dentifrice, dental biofilm formation can be inhibited. Furthermore, this

many essential oils make them beneficial antibiofilm agent [46].

decreased biofilm activity with improved ciprofloxacin efficiency [47].

oil helps in preventing and controlling periodontal diseases [41].

on sub-lethal concentrations of 0.001% (w/v) [41].

The antimicrobial activity of "tea tree" essential oils scientifically named *Melaleuca alternifolia*, synergistically with ciprofloxacin was also evaluated against '*P. aeruginosa'* biofilms. The consequences showed that the combined effect of TTO with ciprofloxacin has decreased biofilm biomass significantly by more than 70% and lowered the number of cells at the lowest (1.25 μg/mL) ciprofloxacin concentration. The efficacy of essential oils from *cinnamon (Cinnamomum verum),* namely *thymol*, and *oregano* at sub-lethal concentrations on biofilm formation of 3 biofilmforming bacterial strains i.e. *Stenotrophomonas*, *Acinetobacter* and *Sphingomonas* were assessed. Researchers showed that at the MIC, two out of three strains revealed resistance on microbial biofilm formation. Furthermore, among the three tested oils, "*thyme oil*" was considered as more efficient and showed inhibitory effect even

Since biofilms are abundant in nature, the importance of biofilms in hospitals especially regarding their role in infections is often undervalued. Future studies should attempt to comprehend the biological forces controlling the colonization to develop innovative strategies for controlling biofilm biomass within a clinical context. Additionally, comprehensive research is required to recognize the potential

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**8. Conclusion**

The authors declare no conflict of interest.
