Preliminary Study On The Characteristics And Mechanism During The Rapid-growth Of Propionibacterium Acnes Stimulated By Ethyl Ferulate

Microorganisms in termite gut,on one hand,participate in the carbon cycle of lignocellulose,and On the other hand,they also play an important role in constantly changing the composition of microorganisms in soil habitats.In this study,a strain of Propionibacterium acnes was screened during the screening of intestinal symbiotic microorganisms with ferulic acid ethyl ester as the sole carbon source,and P.acnes screened from the termite intestine was surprisingly discovered.Extremely fast growth can be achieved with ferulic acid ethyl ester as the sole carbon source.P.acnes was previously thought to grow only in conventional nutrient-rich media and grow very slowly,with colonies visible on the medium over as long as five days.Therefore,this unexpected discovery has caused us great interest.In our previous preliminary experiments,not only P.acnes was screened in termites Reticulitermes labralis but also in termites Coptotermes formosanus.As a wide host range of commensal bacteria that is widely distributed not only on human skin but also in soil insect guts,bovine rumen.Different microorganisms may evolve different characteristics and functions in different ecological environments.it is possible to evolve different microbial growth characteristics and specific biological functions in different environments of the symbiosis of the termite intestinal tract and the parasitic of human body surface.However,the mutual connection and influence in this aspect still require further research and disclosure.This study compared the growth characteristics of strain P.acnes AYC-1,which was selected from the intestine of termite Reticulitermes labralis,with a typical strain P.acnes ATCC 6919,which was derived from human skin.Moreover,the metabolic mechanism of P.acnes using ferulic acid ethyl ester was explored.The main results of this study are summarized as follows:(1)The symbiotic microorganisms in the intestinal tract of R.labralis were screened by a screening medium with ferulic acid ethyl ester as the sole carbon source,and a dominant strain AYC-1 was isolated.The 16 S rDNA sequencing analysis showed that the strain was associated with P.acnes,with similarity as high as 99.9% with several know strains of P.acnes.Therefore,the isolated strain is P.acnes.(2)Ethyl ferulate has a similar stimulatory effect on the growth of AYC-1 from Reticulitermes labralis termite,and typical strain ATCC 6919 from human skin.In addition,the growth of mycelium was positively correlated with the concentration of ethyl ferulate.When the concentration of ethyl ferulate is too low(?1.4 g/L),there is no stimulation of growth.In the solid medium containing 3.6 g/L ferulic acid ethyl ester,the growth rate of mycelial for both strains were as high as 1.01 cm/h.The aerobic condition and the solid culture medium seem to provide good niche for ferulic acid ethyl ester to promote the fast growth of P.acnes,.Finally,the strain AYC-1 isolated from R.labralis also has a nitrogen-fixing ability.(3)The mechanism of the rapid growth of P.acnes on ethyl ferulate was discussed.The crude enzyme solution of strain AYC-1 contained no esterase activity toward ethyl ferulate;strain AYC-1 could not grow on the hydrolysates of ethyl ferulate(ferulic acid and ethanol).It can be concluded that ethyl ferulate is not hydrolyzed and is likely to be oxidatively degraded.A variety of structural analogs of oxidatively degraded were used as substrates.Both strains did not grow,indicating that the two strains have a high specificity for the uptake of ethyl ferulate.