Submitted Abstract
Probiotics denote live microorganisms which when administered in adequate amounts confer a health benefit to the human host. The advancement of nutrigenomics and genomics has provided insight into the modulatory role of probiotic microflora on the signalling and immune system response pathways. A large number of epidemiological data have supported the impact of of gut-microbiome interactions on the etiopathogenesis of several pathological states such as obesity, cardiovascular/circulatory disease, inflammatory bowel disease, traveller’s diarrhoea and several forms of cancer of the gastrointestinal tract. Gut microbiome “transplantation” via the orogastrointestinal route can be achieved by the ingestion of either fresh fermentation food products or dehydrated supplements embedding viable bacterial cells, the latter known as anhydrobiotics. Although anhydrobiotics constitute sustainable and technologically resilient delivery systems, several techno-functional prerequisites must be met in order to ensure their maximal biological activity. In the present project we aim to the systematic investigation of plant seed mucilage gums as multifaceted structuration materials of milk protein based spray dried microcarriers conveying L. rhamnosus GG living cells. The PSGs scaffolding ability i.e. structurally and physico-mechanically reinforced substrates promoting endurance of the conveying living cells upon their exposure to toxic extrinsic and intrinsic conditions associated with processing and storage e.g. osmotic, heat, oxygen or free radicals stress will be assessed. In addition, the PSGs ability to hamper Lactobacilli cells sub-lethality throughout OGI due to acid, osmolytic and enzymolytic stress, as well as their capacity to promote the adhesion interactions between the Lactobacilli surface structure elements and the mucosa coat of a human intestine epithelium cell line model (Caco-2 and HT-29) will be critically evaluated. PROCEED aims to the extraction and isolation of PSGs from plant seed husk biomass of the Brassicaceae, Linaceae and Plantaginaceae species. The PSGs’ composition (total carbohydrate and protein, uronic acid, carbohydrate monomers) as well as their physicochemical profile (viscosity, molecular weight, surface charge and hydrodynamic radii) and prebiotic potential score will be determined. The PSGs structuring ability, the mucoadhesivity and their Lactobacilli cell adhesion properties as influenced by the absence or presence of milk proteins and the cells surface architecture will be also investigated. Spray dried PSG/milk protein microcarriers conveying L. rhamnosus GG (non or EPS producing) will be produced and technologically characterised i.e. physical state, microstructure, water sorption etc. The lethality of the embedded L. rhamnosus GG cells throughout processing, controlled (temperature & relative humidity) storage and in vitro OGI conditions will be tested by means of microbiological enumeration methods and CLSM/Livedead stain kit. Cells inactivation data will be fitted to both Arrhenius and non-Arrhenius (WLF) kinetic models depending carriers’ physical state. The ability of the PSG structured microcarriers to allow controlled disintegration in oral and intragastric phases and promote probiotic cells’ adhesion to a model mucosa producing intestine epithelium co-culture system will be tested using both microscopy, image analysis and microbiological enumeration tools. Significance and impact to the field: It is envisaged that the present project will provide new concepts on sustainable, eco-green/clean label and cost efficient exploitation of under-utilised bio-resources for bespoke pharmabiotic applications. Moreover, the construction of a cross-disciplinary mechanistic basis outlining the interplay between PSGs, probiotic living cells and mucosa layers of the OGI tract tissues is hereby aspired.