Study On Degummed Enzyme System And Its Degumming Method Of Bacillus Cereus HDYM - 02

Flax degumming is the key link in the process of flax textile fiber production. Biological degumming aim to screening of degumming bacteria using in flax stem degumming. Pure fiber can be extracted via enzyme component such as pectinase and hemicellulase secrete by degumming bacteria. Compared with traditional degumming technology, flax biological degumming technology has great advantages and application prospects on retting period, quality of flax fiber, environmental pollution and retting costs.Degumming bacteria number and the dynamic changes of the enzyme degumming is key characterization parameters in biology degumming process. In this topic three stages of the research were carried out following Bacillus cereus HDYM-02 as test bacteria, Bacillus licheniformis HDYM-03 and B.licheniformis HDYM-04 as control.First, in order to investgate the degummase process and enzyme component of test bacteria, inoculation of test bacteria was carried out in peptone medium(BP), pectin fermentation medium(PEC), konjac powder fermentation medium(KGM) and cellulose fermentation medium(CMC). And then preparation conditions of degumming crude enzyme would be determined. Results revealed that HDYM-02 strain can produce pectinase, mannanase and xylanase in PEC and KGM. The highest activity of pectinase in PEC(48 h) and KGM(72 h) were 1115.1±28.7 U/mL and 666.7±8.6 U/mL, respectively, which significantly different from control strains. The highest activity of mannanase in PEC(48 h) and KGM(48 h) were 198.3±1.4 U/mL and 3010.5±31.4 U/mL, which is significantly different from other control strains. Cellulase can not be produced by B.cereus HDYM-02 in CMC medium. Therefore, HDYM-02 strain was selected as degumming bacteria.Secondly, crude enzyme P and crude enzyme K was prepared from PEC and KGM The properties of pectinase and mannanase from crude enzyme P and crude enzyme K were analyzed, it turned out that pectinase and mannanase have preferable stability of enzyme activity at pH 5.0-6.0 and temperature 35-40℃.At last, B.cereus HDYM-02 was selected as degumming bacteria, For exploring the best way of flax degumming, natural degumming, bacteria degumming, crude enzyme degumming and commodity enzyme degumming were build. Bacteria degumming(BA) and natural degumming(CK) were compared, results showed pectinase activity of BA(72 h) reach 200.1±4.9 U/mL, activity of mannanase and xylanase were 169.4±3.0 U/mL and 139.4±4.0 U/mL, above enzyme activities of BA have significance difference compared to CK group. Morphology observation results showed flax of BA group becomes more smoother and transparent, degumming time of BA group shortens 24 h compared with CK group. Compared with bacteria degumming and crude enzyme degumming, the highest activity of pectinase in P group and K group was 731.0±9.2 U/mL and 490.1±19.4 U/mL, respectively, higher than BA with significant difference. Mannanase activity of K group in 60 h was 2388.6±51.2 U/mL which is significant higher than other groups. Degumming time of P group was ahead of 12 h than BA group. The results of flax fiber electron microscopy showed that fiber dispersion of P group was best. Results showed that degumming effect of P group utilizing B.cereus HDYM-02 as test strain was superior to bacteria degumming.In this study, B.cereus HDYM-02 has distinct advantages on degumming with shorter degumming time and richer degumming enzymes. Due to the mild function conditions and good stability of enzyme, crude enzymes of B.cereus HDYM-02 untilized in degumming with ideal effect. The selected bacteria exert promising potential in the applications of flax biological degumming. The research not only provides a vital support for biological degumming but provides the theory basis for the further application of B.cereus HDYM-02 strain.