Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.
Two microsporidia species have been shown to infect Apis mellifera, Nosema apis and Nosema ceranae. This work presents evidence that N. ceranae infection significantly suppresses the honey bee immune response, although this effect was not observed following infection with N. apis. Immune suppression would also increase susceptibility to other bee pathogens and senescence. Despite the importance of both Nosema species in honey bee health, there is no information about their effect on the bees' immune system and present results can explain the different virulence between both microsporidia infecting honeybees.
Due to their social behaviour, honey bees can be infected by a wide range of pathogens including the microsporidia Nosema ceranae and the bacteria Paenibacillus larvae. The use of probiotics as food additives for the control or prevention of infectious diseases is a widely used approach to improve human and animal health. In this work, we generated a mixture of four Lactobacillus kunkeei strains isolated from the gut microbial community of bees, and evaluated its potential beneficial effect on larvae and adult bees. Its administration in controlled laboratory models was safe for larvae and bees; it did not affect the expression of immune-related genes and it was able to decrease the mortality associated to P. larvae infection in larvae and the counts of N. ceranae spores from adult honey bees. These promising results suggest that this beneficial microorganism's mixture may be an attractive strategy to improve bee health. Field studies are being carried out to evaluate its effect in naturally infected colonies.
Proteus mirabilis, a common cause of urinary tract infection, produces a number of different fimbriae, including ambient temperature fimbriae (ATF). These fimbriae are optimally expressed at 23³C and their contribution to urinary tract infection has so far remained unknown. In the present study, a clinical isolate of P. mirabilis and an isogenic allelic replacement mutant unable to express ATF were tested for their ability to cause infection in the ascending urinary tract infection model in mice. The atf mutant colonised the urinary tract as well as the wild-type strain and was also able to outcompete the wild-type strain in a co-challenge experiment. Different non-clinical P. mirabilis isolates showed a reactive AtfA band after Western blot analysis using a polyclonal rabbit AtfA antiserum. These data together suggest that ATF does not play a role in P. mirabilis urinary tract infection. ß
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