Encapsulation of probiotic bacterial culture Lactobacillus plantarum in a polysaccharide alginate matrix

Razumevanje človekove vpetosti v sobivanje z mikroorganizmi je nujen in neobhoden del pri zagotavljanju človekovega zdravja, vse od rojstva pa do smrti. Raziskave kažejo, da igra tako razumevanje izjemno pomembno vlogo tako v pravilnem razvoju novorojenca kot tudi v nadaljnjem človekovem življenju mikrobiota prebavnega trakta, kajti pomembno je pravilno razmerje med različnimi vrstami in zastopanost koristnih bakterij. V primerih, ko pride do porušenja ravnovesja zastopanosti različnih bakterijskih vrst, je nujna njihova čimprejšnja ponovna vzpostavitev. Za človeka najmanj invaziven način za dosego tega cilja je oralno zaužitje pripravkov s probiotiki, to je sevi, ki dokazano koristno učinkujejo na gostitelja, ki pa morajo biti pripravljeni na način, da preživijo želodčno bariero z izredno nizkimi vrednostmi pH (vse do 1,2). Za ta namen smo, kulturo probiotičnih bakterij Lactobacillus plantarum ATCC 8014/IM 308, zamrežili v kroglice polisaharidnega matriksa alginata, s povprečnim premerom kroglic 300 µm. Tako pripravljene kroglice služijo kot transportni medij v človekova prebavila. Alginat se je v tem primeru izkazal za posebej primernega, saj se v kislem okolju še bolj zamreži, kar ujete celice L. plantarum dodatno zaščiti, medtem ko pri nevtralnem pH, ki prevladuje v črevesju, postopoma sprosti svojo vsebino v okolje prebavnega trakta. Viabilnost celic smo spremljali s konfokalnim mikroskopom, s kontrastnim fluorescenčnim barvanjem. Alginat se je izkazal kot primeren in netoksičen nosilec za probiotično kulturo L. plantarum. Viabilnost kapsuliranih celic je bila po 3-urni inkubaciji, v razmerah, ki imitrajo tiste v želodcu (pH 2,0, temperatura 37 ºC, stresanje pri 200 obr./min), skoraj nespremenjena, medtem ko so nekapsulirane bakterije v teh razmerah, izkazale zaznavno propadanje.Understanding of human coexistence with microorganisms is of paramount importance considering human health, all the way from birth to death. Evidence shows that during the development of newborns as well as the rest of the human life, right ratio of different bacterial species and presence of beneficial bacteria, is of vital importance. In cases of this ratios disbalances equillibrium must be reestablished as soon as possible. Least invasive manner of acieving this goal in human is via oral administration of probiotics, strains with demonstrated beneficial effects on the host. These have to be prepared in a way that enables them survival during their passage through harsh acidic barier (pH as low as 1,2) of a stomach. Considering those facts, we prepared alginate microbeads with previoulsy prepared and consequently entrapped probiotic bacterial culture of Lactobacillus plantarum ATCC 8014/IM 308. Microbeads (in average 300 µm in diameter) serve as a transport vector to human gut. Alginate proves itself especially adequate for this kind of usage, as in acidic environment it shrinks even more, wich provides even more protection for the entraped probiotic culture, while exposed to neutral pH values, similar to those in human gut it slowly dissolves releasing it\u27s contents in the environment. We monitored cell viability using fluorecence contrast dyeing and confocal microscopy. Alginate proves itself as an appropriate nontoxic vector of probiotic L. plantarum. Cell viability was remarkably higher in encapsulated, compared to non-encapsulated bacteria, while exposed to environment simulating human stomach (3 hours at pH value 2,0 and temperature of 37 ºC, shaken at 200 rpm.)