Consuming Different Structural Parts of Bamboo Induce Gut Microbiome Changes in Captive Giant Pandas.

Giant pandas consume different structural parts of bamboo (shoots, leaves and culms) during different seasons. Previous research showed different bamboo parts have varying nutritional content and that a long-term diet consisting of a single part of bamboo resulted in remarkable metabolic changes within captive giant pandas. However, the effects on the gut microbiome of giant pandas, as a result of a single bamboo part diet, have not been investigated. Here, we evaluated the changes in gut microbial communities based on single bamboo part diets and their potential implications by using 16S rRNA gene-based amplicon sequencing and metagenome shotgun sequencing. We found that the composition and function of the gut microbiome from captive giant pandas fed exclusively culms were significantly different from that of individuals fed shoots or leaves. During the culm feeding period, the gut microbiome showed strongest digestive capabilities for cellulose, hemicellulose and starch, and had the highest potential abilities for the biosynthesis of bile acids, fatty acids and amino acids. This suggests the microbiome aids in breaking down culm, which is more difficult for giant pandas to digest, as a means to compensate for the nutrient poor content of the culm. Genes related to fatty acid metabolism and tricarboxylic acid cycle enzymes were more abundant during the leaf stage diet than that in the shoot and culm stages. Thus, the microbiome may help giant pandas, which typically have low lipase levels, with fat digestion. These results illustrate that adaptive changes in the gut microbiome community and function may be an important mechanism to aid giant panda digestion when consuming different structural parts of bamboo.

The response of foodborne pathogens to osmotic and desiccation stresses in the food chain.

In combination with other strategies, hyperosmolarity and desiccation are frequently used by the food processing industry as a means to prevent bacterial proliferation, and particularly that of foodborne pathogens, in food products. However, it is increasingly observed that bacteria, including human pathogens, encode mechanisms to survive and withstand these stresses. This review provides an overview of the mechanisms employed by Salmonella spp., Shiga toxin producing E. coli, Cronobacter spp., Listeria monocytogenes and Campylobacter spp. to tolerate osmotic and desiccation stresses and identifies gaps in knowledge which need to be addressed to ensure the safety of low water activity and desiccated food products.