Isolation of Bacillus cereus P05 and Pseudomonas sp. X12 and their application in the ramie retting

Two bacterial strains that express high levels of pectinase and xylanase, named P05 and X12, were isolated from the soil of a ramie garden using pectinase and xylanase selective medium. A bioaugmentation experiment for ramie retting using these bacterial strains showed a significant increase in retting rate when equal ratios of P05 and X12 were mixed into the retting solution at 20% of the volume. Using bioaugmentation, the retting process was completed at 60 h, reducing the retting period by 50%, and the gum removal ratio improved by 79.6%. In addition, the breaking strength of the resulting fiber was increased by 52.3%. Analysis of bacterial population structure and enzyme activity levels in the bioaugmented retting system showed that P05 and X12 quickly became the dominant bacteria within the retting solution microflora, and improved the microflora's ability to produce key retting enzymes. The maximum pectinase and xylanase activities in the bioaugmented retting system were 80.84 U/mL and 50.51 U/mL, respectively, which were 68.98% and 64.21% higher respectively when compared to the control. Thus, addition of P05 and X12 into the retting solution resulted in accelerated gum degradation and fiber separation.