title: Exogenous transglutaminase improves multiple-stress tolerance in Lactococcus lactis and other lactic acid bacteria with glutamine and lysine in the cell wall.
abstract: OBJECTIVE
  To increase the resistance of ingested bacteria to multiple environmental stresses, the role of transglutaminase in Lactococcus lactis and possible mechanisms of action were explored.
  
  
  RESULTS
  L. lactis grown with transglutaminase exhibited significantly higher resistance to bile salts, stimulated gastric juice, antibiotics, NaCl, and cold stress compared to the control (cultured without transglutaminase), with no negative influence on cell growth. Transmission electron microscopy revealed that the cell walls of L. lactis cultured with 9 U transglutaminase/ml were approx. 1.9-times thicker than the control. Further analysis demonstrated that the multi-resistant phenotype was strain-specific; that is, it occurred in bacteria with the presence of glutamine and lysine in the peptidoglycan.
  
  
  CONCLUSIONS
  Supplementation of culture media with transglutaminase is an effective, simple, and inexpensive strategy to protect specific ingested bacteria against multiple environmental challenges.
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China.
authors: Yu
authors: Y
authors: Li
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China.
authors: Zhipeng
authors: Z
authors: Kan
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China.
authors: Yuanli
authors: Y
authors: You
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China.
authors: Xueling
authors: X
authors: Gao
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China.
authors: Zhigeng
authors: Z
authors: Wang
authors: Anhui Engineering Laboratory, School of Tea and Food Science, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, China. ruiyanfu@189.cn.
authors: Ruiyan
authors: R
authors: Fu
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000648:ultrastructure; D003080:Cold Temperature; D005973:Glutamine / Q000032:analysis*; D052197:Limosilactobacillus fermentum / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D013294:Lactococcus lactis / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D008239:Lysine / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D010457:Peptidoglycan / Q000032:analysis; D013312:Stress, Physiological; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D010457:Peptidoglycan; D005973:Glutamine; D011503:Transglutaminases; D008239:Lysine
keywords: Cell wall; Lactic acid bacteria; Lactococcus lactis; Multiple-stress tolerance; Transglutaminase