Effect of bacterial cellulose impregnated with plant extracts and essential oils on the growth of Cronobacter bacteria
Justyna Płoska 1 Lidia Stasiak-Różańska 1 Martyna Dąbrowska 2
2Warsaw University of Life Sciences, Faculty of Food Technology
Bacterial cellulose (BC) is a biopolymer produced, among others by some acetic acid bacteria strains. Due to its unique properties, bacterial cellulose is used as a substitute for plant cellulose. The ability to absorb various compounds and permeability to liquids and gases caused that BC is mainly used in medicine as a wound dressing and drug carrier. In recent years, there has been an increased interest in this biopolymer as a material with potential to be the basis of biodegradable food packaging enriched with bioactive substances. Plant extracts are products obtained from plant raw material by extraction the desired component with a solvent. Essential oils are aromatic substances of plant origin, accumulated in the secretory tissues of the plant as the end product of metabolism. The aim of the study was to investigate the effect of bacterial cellulose produced by the strain Gluconacetobacter hansenii ATCC 23769 soaked with 20% and 50% of aqueous solutions of plant extracts (tulsi, brahmi, blackberry, lemon, nettle root, nettle leaves) as well as essential oils (cinnamon, mint, sage, clove) on growth of choosen Cronobacter sp.: C. muytjensii, C. sakazakii, C. condimenti, C. turicensis and C. malonaticus The antimicrobial activity of BC soaked with the active componed was tested using the disk diffusion method. In addition, the water activity of dry cellulose and the absorption capacity of extracts and oils by BC were tested. The aqueous solutions of the extracts, at a concentration of 20%, showed no antimicrobial activity against the tested strains. For 50% aqueous extracts, only brahmi showed moderate growth inhibitory activity for five of the seven tested strains. The tested strains were characterized by significant sensitivity to cinnamon oil, moderate for clove and peppermint oils, while sage oil turned out to be a weak growth inhibitor of the tested Cronobacter strains. The results of measuring the absorption capacity of plant extracts by cellulose showed that this biopolymer best absorbed the extract of brahmi, lemon, nettle root and leaves. In the case of the absorption of essential oils, it was observed that clove and mint oils were well absorbed by biocellulose. The present study showed that bacterial cellulose is a good carrier of bioactive substances contained in plant extracts and essential oils. Thus, it is possible to develop biodegradable packaging based on bacterial cellulose enriched with bioactive substances. The obtained results allow to plan further studies aimed at characterizing the properties of various types of BC in view of their ability to absorb various substances. In addition, it is reasonable that further studies should focus on the optimization of the concentration of selected bioactive components inhibiting microbial growth in food products.