RESUMO
Choerospondias axillaris fruit has attracted more and more attention due to its various pharmacological activities, which are rich in polysaccharides. This study investigated the in vitro saliva-gastrointestinal digestion and fecal fermentation behaviors of polysaccharides from Choerospondias axillaris fruit (CAP), as well as its impact on human gut microbiota. The results showed that CAP could be partially degraded during the gastrointestinal digestion. The FT-IR spectra of the digested CAP didn't change significantly, however, the morphological feature of SEM changed to disordered flocculent and rod-like structures. 16S rRNA sequencing analysis found that after in vitro fermentation, CAP could increase the relative abundances of beneficial bacteria including Megasphaera, Megamonas and Bifidobacterium to produce short-chain fatty acids (SCFAs), while it can also reduce the abundances of harmful bacteria of Collinsella, Gemmiger, Klebsiella and Citrobacter, suggesting that CAP could modulate the composition and abundance of gut microbiota. These results implied that CAP can be developed as a potential prebiotic in the future.
RESUMO
Under the macroenvironmental background of global warming, all countries are working to limit climate change. Internationally, biofuel plants are considered to have great potential in carbon neutralization. Several countries have begun using biofuel crops as energy sources to neutralize carbon emissions. Switchgrass (Panicum virgatum) is considered a resource-efficient low-input crop that produces bioenergy. In this paper, we reviewed the effects of switchgrass cultivation on carbon sequestration and greenhouse gas (GHG) emissions. Moreover, the future application and research of switchgrass are discussed and prospected. Switchgrass has huge aboveground and underground biomass, manifesting its huge carbon sequestration potential. The net change of soil surface 30 cm soil organic carbon in 15 years is predicted to be 6.49 Mg ha-1, significantly higher than that of other crops. In addition, its net ecosystem CO2 exchange is about -485 to -118 g C m-2 yr-1, which greatly affects the annual CO2 flux of the cultivation environment. Nitrogen (N) fertilizer is the main source of N2O emission in the switchgrass field. Nitrogen addition increases the yield of switchgrass and also increases the N2O flux of switchgrass soil. It is necessary to formulate the most appropriate N fertilizer application strategy. CH4 emissions are also an important indicator of carbon debt. The effects of switchgrass cultivation on CH4 emissions may be significant but are often ignored. Future studies on GHG emissions by switchgrass should also focus on CH4. In conclusion, as a biofuel crop, switchgrass can well balance the effects of climate change. It is necessary to conduct studies of switchgrass globally with the long-term dimension of climate change effects.
