Lactobacillus Plantarum Cell Wall Peptide Glycan Microencapsulation And In Vivo Sustained Release Effect Evaluation

The Lactobacillus plantarum screened from the Northeastern pickle was used as experimental strain, and the modified trichloroacetic acid method was applied to extract peptidoglycan from the strain. The extracts were identified structurally and analyzed physico-chemically. The extracted peptidoglycan was microencapsulated using chitosan. The oral administration of peptidoglycan microspheres was tested for the sustained release using mouse as experimental animals. The major experimental procedure and results are as follows:(1) The peptidoglycan was extracted by modified trichloroacetic acid method, and its yield was 15.29±1.28%, in which the total sugar content was 39.10±1.95%, lipid content was 1.41±0.04%, protein content was 58.00±2.16%. The four amino acids that comprised joint peptides of the basic structural units of Lactobacillus peptidoglycan (alanine, glutamic acid, aspartic acid, lysine) showed significantly higher content than those in integrated bacterium powder. Fourier transform infrared spectroscopy (FTIR) analysis showed that the extracts have characteristic peptidoglycan structure.(2)Chitosan microspheres encapsulating peptidoglycan was prepared by emulsion-crosslinking method with stable technological process and good repeatability. The microspheres showed good spherical features with rough surface. The average drug loading capacity (LC) and encapsulation efficiency (EE) of microspheres varied with different ratio between peptidoglycan and chitosan. At the ratio of 1:1, the LC and EE was 37.00±3.24g/100g and 92.00±2.38%, respectively.(3)Animal tests were carried out by gavaging mouse with naked peptidoglycan or peptidoglycan microspheres consecutively for a week at low, medium and high dose. Blood was obtained from tails at 3d intervals within 15d; then enzyme-linked immunosorbent assay (ELISA) was used to measure the lysozyme content in serum. The peptidoglycan-encapsulated microsphere groups with different dose showed highest lysozyme content in serum and reached the highest value at the 9d post administration, and the high level lysozyme content lasted to the 15th day after vaccination. The chitosan microspheres showed significantly sustained effect on peptidoglycan release. which can effectively extend the action time for peptidoglycan.This is the first study on microcapsulation of peptidoglycan and then administered by oral route. This route overcame the troubles brought by traditional injection way for peptidoglycan delivery. The study may pave a way for further study on the use of peptidoglycan as adjuvant, and provide a reference for the development of oral vaccine.