Gut microbiota plays a crucial role in the pathophysiology of depression. This study aimed to explore the antidepressant effect of mature whole C. aurantium fruit extract (FEMC) in the chronic unpredictable mild stress (CUMS) model. The behavioral tests were applied to assess antidepressant effect and 16S rRNA sequencing was used to analyze the changes of gut microbiota. The results showed that the major components of FEMC were naringin and neohesperidin and significantly increased the sucrose preference index of the mice. FEMC also could reduce the feeding latency in an open field test and the rest time in a novelty suppressed feeding test. In addition, FEMC could increase CUMS-induced reduction in the levels of BDNF, PSD95, and SYN in the hippocampus. Moreover, FEMC intervention slightly decreased the ratio of Firmicutes to Bacteroidota. Meanwhile, FEMC reduced the abundance of the Prevotellaceae_Ga6A1_group, [Ruminococcus]_torques_group, which have been reported to be closely related to inflammation. Bioinformatics analysis revealed that MAPK signaling pathway and lipopolysaccharide biosynthesis were involved in the anti-inflammatory effect of FEMC in the CUMS animal model. Finally, the ELISA results showed that FEMC could significantly reduce the expression of pro-inflammatory cytokines IL-6 and TNF-α in the serum of depressive mice. Our results suggest FEMC can ameliorate depressive behavior by inhibiting gut microbiota-mediated inflammation in mice.

The microbial potential of Penicillium has received critical attention. The present research aimed to elucidate the efficacy of crude enzyme secreted from Penicillium oxalicum WX-209 in degrading citrus segments and evaluate the safety of the process. Results showed that citrus segment membranes gradually dissolved after treatment with the crude enzyme solution, indicating good degradation capability. No significant differences in body weight, food ingestion rate, hematology, blood biochemistry, and weight changes of different organs were found between the enzyme intake and control groups. Serial experiments showed that the crude enzyme had high biological safety. Moreover, the whole genome of P. oxalicum WX-209 was sequenced by PacBio and Illumina platforms. Twenty-five scaffolds were assembled to generate 36 Mbp size of genome sequence comprising 11369 predicted genes modeled with a GC content of 48.33%. A total of 592 genes were annotated to encode enzymes related to carbohydrates, and some degradation enzyme genes were identified in strain P. oxalicum WX-209.