Synergistic antifungal effects of essential oils and lactobacillus plantarum cell-free supernatant against penicillium spp. and in situ effects in rice | |
| Author | Suphamid Sriwattanachai |
| Call Number | AIT Thesis no.FB-16-01 |
| Subject(s) | Lactobacillus casei Penicillium |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. no.FB-16-01 |
| Abstract | Essential oils and lactic acid bacteriahave shownthepotentialas biopreservationsto control the growth of moulds. Their applications in foods, however,arestilllimited becauseof their requiredminimum inhibitory concentrations(MICs),and negative effects on organoleptic propertiesof foods.The synergistic antifungal effects betweenthree essential oils, namely thyme, cinnamon, and cloveand lactic acid bacteria cell-free supernatantof Lactobacillusplantarumagainst Penicillium spp.in vitroand in situwere evaluated in this studyin order to reduce the required minimum inhibitory concentrationsand aid the industrial applications.Lactobacillusplantarumproduced the highestyield of antifungal metabolites in its supernatant within60 hoursof fermentationat 30 oC.Tween 80,2% (v/v),was requiredto disperse thyme, cinnamon, and cloveessential oilsin theculturemedia(Potato Dextrose Broth). Theminimum inhibitory concentrationsof thyme, cinnamon,cloveessential oils, and 17x concentrated lactic acid bacteria cell-free supernatant against Penicillium spp.were also found to be 40, 1, 10, and 80 μl/mlrespectively. Furthermore,the fractional inhibitory concentration(FIC)indexshowedthe antifungal synergy betweenthyme essential oils and 17x concentrated lactic acid bacteria cell-free supernatantin vitrowith at leastfour-fold reduction oftheirrespectiveminimum inhibitory concentrations, whereas the other combinations only showedthe additive effects. These synergieswere found to exert their modes of actionsthrough the disruption of cytoplasmic membrane and the degradation of chitin on the fungal cell wall, butnotthrough the enhancement of antioxidant activity as determined by total phenolic content, DPPH scavenging activity,and ferric reducing antioxidant powerassay. In addition, the in situantifungal analyses showed the effectiveinhibitionsof the combined mixture against Penicillium spp.in both artificial and natural contaminations, suggesting its actual applications in rice.To the best knowledge of the author, this isthe first time that the synergistic antifungal effectsbetween thyme essential oils and 17xconcentratedlactic acid bacteria cell-free supernatantandtheirs modesof actions against Penicillium spp.have been characterized and reported.A significant breakthrough onthe synergy study betweenessential oils and lactic acid bacteriahas also been madeby the utilizationof lactic acid bacteria cell-free supernatantand systematic evaluation with fractional inhibitory concentrationindex.Keywords: Synergistic effects, Antifungal activity, Essential oils,Thyme,Lactobacillus plantarum, Cell-free supernatant, Penicillium spp., Fraction inhibitory concentration,andRice. |
| Year | 2016 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. no.FB-16-01 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Anal, Anil Kumar; |
| Examination Committee(s) | Athapol Noomhorm;Loc Thai Nguyen; |
| Scholarship Donor(s) | Ministry of Agriculture and Cooperatives(MOAC), Thailand;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2016 |