ORIGINAL PAPER Probiotics in the intestinal tract of juvenile whiteleg shrimp Litopenaeus vannamei: modulation of the bacterial community Irasema E. Luis-Villasen ˜or • Thelma Castellanos-Cervantes • Bruno Gomez-Gil • A ´ ngel E. Carrillo-Garcı ´a • A ´ ngel I. Campa-Co ´rdova • Felipe Ascencio Received: 9 July 2012 / Accepted: 18 September 2012 / Published online: 18 November 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Molecular analysis of the 16S rDNA of the intestinal microbiota of whiteleg shrimp Litopenaeus van- namei was examined to investigate the effect of a Bacillus mix (Bacillus endophyticus YC3-b, Bacillus endophyticus C2-2, Bacillus tequilensisYC5-2) and the commercial probiotic (Alibio Ò ) on intestinal bacterial communities and resistance to Vibrio infection. PCR and single strain con- formation polymorphism (SSCP) analyses were then per- formed on DNA extracted directly from guts. Injection of shrimp with V. parahaemolyticus at 2.5 9 10 5 CFU g -1 per shrimp followed 168 h after inoculation with Bacillus mix or the Alibio probiotic or the positive control. Diver- sity analyses showed that the bacterial community resulting from the Bacillus mix had the highest diversity and even- ness and the bacterial community of the control had the lowest diversity. The bacterial community treated with probiotics mainly consisted of a- and c-proteobacteria, fusobacteria, sphingobacteria, and flavobacteria, while the control mainly consisted of a-proteobacteria and flavo- bacteria. Differences were grouped using principal com- ponent analyses of PCR-SSCP of the microbiota, according to the time of inoculation. In Vibrio parahaemolyticus- infected shrimp, the Bacillus mix (*33 %) induced a significant increase in survival compared to Alibio (*21 %) and the control (*9 %). We conclude that administration of the Bacillus mix induced modulation of the intestinal microbiota of L. vannamei and increased its resistance to V. parahaemolyticus. Keywords Whiteleg shrimp Á Bacteria community Á Probiotics Á Bacillus mix Introduction Despite rapid expansion, aquaculture production has been negatively affected by infectious diseases, including viru- ses, rickettsiae, bacteria, fungi, and parasites, causing bil- lions of dollars in losses (Lightner 2005). Increasing demand for aquaculture products has led to indiscriminate use of chemicals and antibiotics, resulting in environmental degradation (Bache ´re 2000). One alternative includes adding probiotics during rearing, either in the water or as feed supplements (Moriarty 1998). Among available pro- biotics, Bacillus bacteria are widely used because it pro- duces spores that are extremely resistant to external physical and chemical processes and produce polypeptides (bacitracin, gramicidin S, polymyxin, and tyrothricin) that are active against a broad range of Gram positive and negative bacteria, including pathogenic vibrios (Morikawa et al. 1992; Perez et al. 1993; Drablos et al. 1999). Composition of aquatic bacterial communities in ponds has a strong influence on the internal bacterial flora of farmed marine animals; this is vital for their nutrition, immunity, and disease resistance (Luo et al. 2006). At the same time, it impacts and is impacted by the bacterial Electronic supplementary material The online version of this article (doi:10.1007/s11274-012-1177-0) contains supplementary material, which is available to authorized users. I. E. Luis-Villasen ˜or Á T. Castellanos-Cervantes Á A ´ . E. Carrillo-Garcı ´a Á A ´ . I. Campa-Co ´rdova Á F. Ascencio (&) Centro de Investigaciones Biolo ´gicas del Noroeste (CIBNOR), Instituto Polite ´cnico Nacional 195, Col. Playa Palo de Santa Rita, 23096 La Paz, B.C.S., Mexico e-mail: ascencio@cibnor.mx B. Gomez-Gil Center for Research in Nutrition and Development (CIAD), Mazatlan Unit for Aquaculture, Mazatla ´n, 82000 Sinaloa, Mexico 123 World J Microbiol Biotechnol (2013) 29:257–265 DOI 10.1007/s11274-012-1177-0