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【Objective】Endophytic bacteria exert an important role in plant growth and development. The study aims to analyze the community structure and diversity of endophytic bacteria in pulp of different litchi varieties, and screen and utilize the potential endophytic bacteria resources, which would provide references for further research on the interaction between litchi and endophytic bacteria.【Method】The pulp tissues of 6 different litchi varieties were used as materials. MiSeq high-throughput sequencing technology was used to compare and analyze the community composition and dominant flora of endophytic bacteria at phylum, family, genus and species classification levels in pulp tissues after the V3~V4 region of 16S rDNA was amplified by PCR. The diversity of endophytic bacteria was evaluated combined with Alpha diversity analysis.【Result】A total of 2 139 086 sequences of endophytic bacteria 16S rDNA were obtained in the V3~V4 region of 6 litchi varieties, and the average length of amplified sequences was 376 bp. There was no significant difference in the abundance and diversity of endophytic bacteria in different litchi varieties. At the phylum classification level, Proteobacteria was the main dominant bacterial group in litchi pulp tissue, followed by Actinomyces. At the levels of family, genus and species classification, the endophytic bacterial community structure of different litchi varieties was similar, but the bacterial abundance proportion was different. Differential bacterial community analysis showed that the Pseudomonas, Pectobacterium, Ochrobactrum and Dickeya were significantly enriched in the high-quality varieties of 'Edanli', 'Nuomici' and 'Guanyinlv'. In addition, Bradyrhizobium and Snodgrassella were only enriched in the 'Edanli'. The clustering analysis of relative abundance of bacteria showed that 'Guanyinlv', 'Nuomici' and 'Edanli', had higher similarity. Alpha diversity analysis showed that there were differences in the abundance and diversity of endophytic flora in pulps of 6 litchi varieties, but the differences were not significant.【Conclusion】In this study, the community structure of endophytic bacteria in the pulp of six different litchi varieties was analyzed, and some unique microbial genera were enriched in the high-quality litchi varieties. The results could provide a theoretical basis and important references for the development and utilization of endophytic bacteria to improve litchi quality.

The deterioration of the quality of litchi pulp is closely related to oxygen and heat treatment. This study compared the effects of conventional beating (CB) and low-oxygen beating (LB) on the quality of litchi pulp, and the effect of low-oxygen beating combined with high hydrostatic pressure (HHP) and heat treatment on the quality of litchi pulp during storage at 4 ℃ was also studied. The results showed that when compared to conventional beating, low-oxygen beating had no significant effect on the total soluble solid, pH and total acid of litchi pulp (P>0.05), while the L* value increased significantly (P

Dried litchi pulp has been used in traditional remedies in China for many years to treat various diseases, and the therapeutic activity has been, at least partly, attributed to the presence of bioactive polysaccharides. Polysaccharide-protein complexes from vacuum freeze-(VF), vacuum microwave-(VM) and heat pump (HP) dried litchi pulp, which were coded as LP-VF, LP-VM and LP-HP, were comparatively studied on the physicochemical and immunomodulatory properties. LP-HP had a predominance of galactose, while glucose was the major sugar component in LP-VF and LP-VM. Compared with LP-VF and LP-VM, LP-HP contained more aspartate and glutamic in binding protein. LP-HP also exhibited a stronger stimulatory effect on splenocyte proliferation at 200 μg/mL and triggered higher NO, TNF-α and IL-6 secretion from RAW264.7 macrophages. Different drying methods caused the difference in physicochemical properties of polysaccharide-protein complexes from dried litchi pulp, which resulted in significantly different immunomodulatory activity. HP drying appears to be the best method for preparing litchi pulp to improve its immunomodulatory properties.