Study On The Effect Of Shading Syringa Oblata Lindl. On Staphylococcus Xylosus Biofilm And Its Active Constituents

At present,there are many hidden factors that lead to mastitis infection in cows.Among them,Staphylococcus xylosus(S.xylosus)is most the prevalent bacteria isolated from infected animals,making it the leading cause of the mastitis infection in dairy cows.S.xylosus is also one of the coagulase-negative staphylococci(Co NS),which has strong ability to form biofilm.Biolfilms can become potential sources of infection,they enable bacteria develop immune tolerance and resistance against antibiotics and the host defence system.This leads to persistent mastitis infection in most cases,making such infections almost incurable.Thus,it is therefore important to find a Chinese medicine that can interfere with the formation of biofilms in S.xylosus.This will go a long way in attenuating bovine mastitis associated with S.xylosus infection in dairy herds.Syringa oblata Lindl.(S.oblata)is a well-known deciduous shrub in China which belong to the family Oleaceae.The leaves of the plant are rich sources of bioactive compounds with high medicinal value.S.oblate has the potential of being used clinically as an effective broad-spectrum antimicrobial with little side effects.The synthesis of active ingredient of medicinal plants is susceptible to environmental influences and these factors may affect their efficacy.The active ingredients of S.oblata have a certain relationship with light intensity in plant photosynthesis.Rutin as the main bioactive ingredient and pharmacodynamic basis in S.oblate which inhibits biofilm formation by Streptococcus suis.Thus,this experiment studied the synthesis of flavonoids represented by rutin in S.oblata by regulating natural light intensity,and assessed the expression pattern of S.oblata in response to shade by metabolite and transcriptome analysis in order to explore the flavonoids biosynthesis and increase the content of rutin.The specific research results are as follows:(1)Rutin and S.oblata extract with different months(May to October in 2017)and shade groups(100 % light intensity Z0,45 % light intensity Z1 and 25 % light intensity Z2 in September2017)had inhibitory effect on biofilm formation by S.xylosus by crystal violet staining.The changes in the rutin and flavonid content of S.oblata with different months and shade groups by HPLC and UV.The results showed that 8 mg/m L rutin had a significant ability to inhibit S.xylosus biofilm formation(p<0.05).Compared with Z0 group S.oblata extract,Z1 group S.oblata extract had a best ability to inhibit S.xylosus biofilm formation(p<0.05)and was highest the rutin andflavonid content.At the same time,the results indicated that the S.oblata under Z1 group had more flavonoids compared with Z0 group in September 2017.(2)The differential metabolites and the differentially expressed Unigenes of S.oblata with Z0 and Z1 by the LC-MS and RNA seq technology.It was found that the adaptation of S.oblata to light stress is a complex regulatory process,and it mainly involves the flavonoid biosynthesis pathway.By flavonoid biosynthetic pathway gene analysis and real-time PCR validation,the results showed that 3 genes such as 4-coumarate-Co A ligase(4CL1,TRINITY_DN35155_c0_g1),trans-cinnamate 4-monooxygenase(CYP73A,TRINITY_DN29851_c0_g2)and flavonoid3'-monooxygenase(CYP75B1,TRINITY_DN31579_c2_g5)were may significantly regulated the metabolite of S.oblata in rutin.In summary,after the shading treatment of S.oblata,by the regulation of flavonoid biosynthesis pathway,the content of the flavonoid component was increased,and the ability to inhibit the biofilm of the S.xylosus was enhanced.It would laid a theoretical foundation for the further development of S.oblata tree GAP.Planting.