The crustacean Artemia franciscana represents a potential experimental model for human studies. The aim of the project was to assess whether Artemia could be used as a model for investigation of probiotic properties. For all the experiments, Artemia cysts were rehydrated, decapsulated and allowed to hatch for 28 hours before the developed larvae (nauplii) were challenged and/or treated with probiotics; measurement of survival rate occurred after further 24 and 48 hours. Interestingly, administration of L. reuteri 17938 during an initial study showed that the probiotic rescued Artemia from spontaneous death occurring in the absence of any established and chosen challenge in a dose-dependent manner. Assuming that Artemia death was related to some kind of stress, the mode of action by means of which L. reuteri provided protective effects was investigated. Heat-treated and bead-beaten L. reuteri positively affected Artemia survival rate to a greater extent than live L. reuteri, with the highest improvement occurring during administration of bead-beaten L. reuteri. In particular, administration of different fractions of the bead-beaten L. reuteri cultures to Artemia allowed for identification of the molecule responsible for amelioration of Artemia fitness in bacterial components ranging between 3 and 300 kDa in weight. Supernatants obtained from exudates of plate-grown bacteria instead revealed itself to be lethal when added in amounts corresponding to 10⁷ CFU/ml of the bacterial culture or higher. Further studies on a genetic and immunological level on Artemia are required in order to elucidate the complex interactions establishing among the host, the probiotic and the environment. However, based on the data gathered, it is possible to suggest that Artemia can be used as a potential chronic stress model, for example as aging or starvation models. Besides this, L. reuteri shows to provide an overall protective effect against this stress, although differences in the extent of the protection were observed according to the growth protocol and the killing mode of bacterial cultures. Also, the lethality of the supernatants demonstrates once again that the probiotic activity is the result of multiple and intertwined biological pathways, sometimes in contrast to one another.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-416151 |
| Date | January 2020 |
| Creators | Racca, Tiziana |
| Publisher | Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, SLU, department of molecular sciences |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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