Search

Background: Diarrhea is an important ailment limiting the production of the Tibetan pig industry. Dynamic balance of the intestinal microbiota is important for the physiology of the animal. The objective of this work was to study fungal diversity in the feces of early weaning Tibetan piglets in different health conditions. Results: In the present study, we performed high-throughput sequencing to characterize the fungal microbial diversity in healthy, diarrheal and treated Tibetan piglets at the Tibet Autonomous Region of the People's Republic of China. The four alpha diversity indices (Chao1, ACE, Shannon and Simpson) revealed no significant differences in the richness across the different groups (P > 0.05). In all samples, the predominant fungal phyla were Ascomycota, Basidiomycota and Rozellomycota. Moreover, the healthy piglets showed a higher abundance of Ascomycota than the treated ones with a decreased level of Basidiomycota. One phylum (Rozellomycota) showed higher abundance in the diarrheal piglets than in the treated. At genus level, compared with that to the healthy group, the proportion of Derxomyces and Lecanicillium decreased, whereas that of Cortinarius and Kazachstania increased in the diarrheal group. The relative abundances of Derxomyces, Phyllozyma and Hydnum were higher in treated piglets than in the diarrheal ones. Conclusions: A decreased relative abundance of beneficial fungi (e.g. Derxomyces and Lecanicillium) may cause diarrhea in the early-weaned Tibetan piglets. Addition of probiotics into the feed may prevent diarrhea at this stage. This study presented the fungal diversity in healthy, diarrheal and treated early-weaned Tibetan piglets. [ABSTRACT FROM AUTHOR]

Background: Aeromonas hydrophila is an opportunistic pathogen of poikilothermic and homoeothermic animals, including humans. In the present study, we described the role of Alanine racemase (alr-2) in the virulence of A. hydrophila using an alr-2 knockout mutant (A.H.Δalr). Results: In mouse and common carp models, the survival of animals challenged with A.H.Δalr was significantly increased compared with the wild-type (WT), and the mutant was also impaired in its ability to replicate in the organs and blood of infected mice and fish. The A.H.Δalr significantly increased phagocytosis by macrophages of the mice and fish. These attenuation effects of alr-2 could be complemented by the addition of D-alanine to the A.H.Δalr strain. The histopathology results indicated that the extent of tissue injury in the WT-infected animals was more severe than in the A.H.Δalr-infected groups. The expression of 9 virulence genes was significantly down-regulated, and 3 outer membrane genes were significantly up-regulated in A.H.Δalr. Conclusions: Our data suggest that alr-2 is essential for the virulence of A. hydrophila. Our findings suggested alanine racemase could be applied in the development of new antibiotics against A. hydrophila. [ABSTRACT FROM AUTHOR]