Interactions Among Pectin-degrading Bacteria And Their Application In Warm Water Retting

Water retting system is a complex ecosystem.The essence of degumming is that the degumming enzymes produced by microorganisms on the flax stem degrade pectin and semi-cellulose gummy substances to obtain bast fibers or fiber bundles.The degumming enzymes mainly include pectinase,mannase and polygalacturonic acid enzymes.Pectin and pectic acid are the dominant gummy substances within flax stems,In this study,water retting ecosystem was constructed as the research model.The main purpose of this research was the degradation of pectin gummy substance,the interaction of bacterial strains who were producers of pectin lyase and pectic acid lyase as well as their application in water retting of flax.The achievements of this study would be helpful to reveal the degumming mechanism and improve industrial process of water retting of flax.First of all,the activity and process of pectin degumming enzymes of eight Bacillus strains preserved by key laboratory of microbiology,Heilongjiang university were investigated in pectin fermentation medium(PEC).Results revealed that the activity of pectate lyase produced by Bacillus licheniformis HDYM-03 was significantly higher than the other,so determine B.licheniformis HDYM-03 as pectate lyase high-yield strains.Bacillus megaterium production pectin lyase activities were significantly higher than the other,and has lower pectate lyase activity,so determine B.megaterium as pectin lyase high-yield strains.Then,determine the best pectin degradation bacteria strains were used to study the degumming enzyme-production process and explore the pectic substance degradation bacteria interactions in PEC and konjac powder fermentation medium(KF).Results revealed that B.megaterium can produce pectin lyase in PEC and KF.The highest activity of pectin lyase in PEC(84 h)was 2423.72±32.59 U/m L,which was significantly different from control strains.The highest activity of pectin lyase in KF(72 h)was 5016.43±73.76 U/m L,which was significantly different from control strains.B.licheniformis HDYM-03 can produce pectate lyase in PEC and KF.The highest activity of pectate lyase in PEC(84 h)and KF(84 h)were 742.61±17.08 U/m L and943.19±12.94 U/m L,respectively,which was significantly different from other control strains.Pectic utilization of B.megaterium in PEC/KF medium was highest.Pectic acid utilization of B.licheniformis HDYM-03 in PEC/KF medium was highest.At last,in the bacteria-adding water retting system(BA)constructed by adding B.licheniformis HDYM-03 and B.megaterium strains were to further explore the pectic substance degradation bacteria degumming process and mechanism of synergy,while the bacteria-adding water retting system(BH)constructed by adding B.licheniformis HDYM-03 strain,the bacteria-adding water retting system(BM)constructed by adding and B.megaterium strain,the water retting system(CK)were used as the control.The results showed that the highest activity of pectin lyase in BA(144 h)was1073.91±15.37 U/m L,which was significantly different from control strains.The highest activity of pectate lyase in BA(120 h)was 220.79±5.93 U/m L,which was significantly different from control strains.Pectic utilization and pectic acid utilization of BA were higher than the control groups.In this study,B.licheniformis HDYM-03 and B.megaterium has distinct advantages on degumming with shorter degumming time and richer degumming enzymes.B.licheniformis HDYM-03 and B.megaterium untilized in degumming with ideal effect.The selected bacteria exerted promising potential in the applications of flax biological degumming.The research provides support for biological degumming methods,as well as add bacteria retting in provides the theory basis for the feasibility of flax degumming industry,is the practice of great realistic significance.