Effect of yeast culture supernatant on the probiotic properties and biochemical characteristics of three probiotics, in vitro and in vivo evaluation of yeast-probiotic combination against the pathogen V. anguillarum

Research hypothesis: If yeast and probiotics enhance each other they might provide improved protection against pathogens. Growth, aggregation, biofilm formation and hydrophobicity as well as evaluation, of pH lactic acid, free amino nitrogen and reducing sugars in the growth media were estimated for probiotics in the presence of three ratios of yeast cell free supernatant (CFS). The effect of the best working ratio of each probiotic with yeast in terms of the characteristics examined, on the fish pathogen Vibrio anguillarum properties, namely aggregation, biofilm formation and hydrophobicity, was studied in vitro. Then an in vivo examination on Artemia franciscana nauplii was performed following administration of yeast and probiotic bacteria at the selected ratios and a challenge test with the pathogen to examine any possible protection offered in terms of Artemia survival.

研究假设：若酵母与益生菌相互增强，则可能提供对病原体的改进保护。在含有酵母细胞游离上清液（CFS）的三种比例下，对益生菌的生长、聚集、生物膜形成和疏水性进行了评估，并对其在生长培养基中的pH、游离氨基酸氮和还原糖进行了测定。研究了每个益生菌与酵母的最佳工作比例在考察特征方面的效应，即对鱼类病原体弧菌属的聚集、生物膜形成和疏水性等特性。随后，在体外进行了实验，以研究该比例下益生菌与酵母对弧菌属特性的影响。接着，在给Artemia franciscana桡足幼虫投喂选定比例的酵母和益生菌细菌后，进行了体内实验，并使用病原体进行挑战测试，以检验对桡足幼虫生存可能提供的保护效果。