HOST MICROBE INTERACTIONS In Vitro and In Vivo Evaluation of the Prebiotics GroBiotic®-A, Inulin, Mannanoligosaccharide, and Galactooligosaccharide on the Digestive Microbiota and Performance of Hybrid Striped Bass (Morone chrysops × Morone saxatilis) Gary Burr & Michael Hume & Steven Ricke & David Nisbet & Delbert Gatlin III Received: 11 February 2009 / Accepted: 27 September 2009 / Published online: 21 October 2009 # Springer Science + Business Media, LLC 2009 Abstract Two separate experiments were conducted with hybrid striped bass to evaluate four potential prebiotics: GroBiotic®-A (partially autolyzed brewer ’s yeast, dairy ingredient components, and fermentation products), man- nanoligosaccharide (MOS), galactooligosaccharide (GOS), and inulin. In the in vitro experiment, intestinal contents were incubated with the individual prebiotics (0.5% by weight) at 25°C for 24 and 48 h. Analysis of volatile fatty acids in the supernatant showed that GroBiotic®-A, MOS, and GOS tended to produce lower acetate levels but higher butyrate levels at 48 h compared to diet alone. However, denaturing gradient gel electrophoresis (DGGE) analysis failed to detect any differences in the composition of the microbial community among treatments. DNA sequencing of a common band for all inoculated samples revealed close similarity to the anaerobic Fusobacteria bacterium. An 8-week feeding trial also was conducted to evaluate the four prebiotics looking at growth performance; weight gain, feed efficiency ratio, protein efficiency ratio, whole-body ash, moisture, and lipid did not vary among fish fed the various diets. However, DGGE analysis revealed that all prebiotics produced a different type of microbial community in the intestinal tract of hybrid striped bass compared to fish fed the basal diet. Thus, GroBiotic®-A, FOS, GOS, and MOS exhibited prebiotic effects in hybrid striped bass. Introduction The microbiota of the gastrointestinal (GI) tract plays an important role in the health and performance of the host [8, 28]. Recently, there has been increased interest in manipulating the GI tract microbial community to enhance the effects of beneficial bacteria on host nutrition and immune response. Without using antibiotics, there are two general approaches used to modify the GI tract bacteria. One involves probiotics, which are viable microorganisms that are added to the diet to benefit the host [8]. The second approach is the addition of prebiotics to the diet. Prebiotics are defined as “nondigestible food ingredients that increase the growth or activity of select members of the endogenous intestinal microbial community and the new community benefits the host” [24]. Prebiotics have been found to have beneficial effects in humans [24], poultry [28], and swine [37]. Reports from these studies reveal that prebiotics can modify the GI tract microbial community to enhance non- G. Burr : D. Gatlin III (*) Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA e-mail: d-gatlin@tamu.edu G. Burr e-mail: gary.burr@ars.usda.gov M. Hume : D. Nisbet Food and Feed Safety Unit, USDA, Agricultural Research Service, College Station, TX 77845, USA M. Hume Department of Poultry Science, Texas A&M University, College Station, TX 77845, USA Present Address: S. Ricke Center for Food Safety, ISFE and Food Science Department, University of Arkansas, Fayetteville, AR 72704, USA Microb Ecol (2010) 59:187–198 DOI 10.1007/s00248-009-9597-6