bacterial capsules


Summary: An envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides.

Top Publications

  1. Ansaldi F, Canepa P, De Florentiis D, Bandettini R, Durando P, Icardi G. Increasing incidence of Streptococcus pneumoniae serotype 19A and emergence of two vaccine escape recombinant ST695 strains in Liguria, Italy, 7 years after implementation of the 7-valent conjugated vaccine. Clin Vaccine Immunol. 2011;18:343-5 pubmed publisher
    ..To our knowledge, this is the first detection of an occurrence of capsular switching outside the United States. ..
  2. Fierer J, Walls L, Chu P. Recurring Klebsiella pneumoniae pyogenic liver abscesses in a resident of San Diego, California, due to a K1 strain carrying the virulence plasmid. J Clin Microbiol. 2011;49:4371-3 pubmed publisher
    ..He was a Caucasian who lived in California and had no epidemiological connection to East Asia. The isolate from his third episode was a hyperviscous K1 strain that carried the Klebsiella virulence plasmid. ..
  3. Hanson B, Lowe B, Neely M. Membrane topology and DNA-binding ability of the Streptococcal CpsA protein. J Bacteriol. 2011;193:411-20 pubmed publisher
    ..Taken together, CpsA, as well as other members of the LytR_cpsA_psr protein family, appears to utilize a unique mechanism of transcriptional regulation. ..
  4. Cornelissen A, Ceyssens P, T Syen J, Van Praet H, Noben J, Shaburova O, et al. The T7-related Pseudomonas putida phage ?15 displays virion-associated biofilm degradation properties. PLoS ONE. 2011;6:e18597 pubmed publisher
    ..These data suggests that the addition of high initial titers of specifically selected phages with a proper EPS depolymerase are crucial criteria in the development of phage therapy. ..
  5. Willenborg J, Fulde M, de Greeff A, Rohde M, Smith H, Valentin Weigand P, et al. Role of glucose and CcpA in capsule expression and virulence of Streptococcus suis. Microbiology. 2011;157:1823-33 pubmed publisher
    ..Taken together, our data demonstrate that CcpA has a significant effect on the capsule synthesis and virulence properties of S. suis. ..
  6. Calix J, Porambo R, Brady A, Larson T, Yother J, Abeygunwardana C, et al. Biochemical, genetic, and serological characterization of two capsule subtypes among Streptococcus pneumoniae Serotype 20 strains: discovery of a new pneumococcal serotype. J Biol Chem. 2012;287:27885-94 pubmed publisher
    ..We propose naming bacteria that express the previously described 20? capsule structure 20A and bacteria that express the novel 20? capsule structure 20B, a new pneumococcal serotype. ..
  7. Chung D, Lee H, Park M, Jung S, Chang H, Kim Y, et al. Fecal carriage of serotype K1 Klebsiella pneumoniae ST23 strains closely related to liver abscess isolates in Koreans living in Korea. Eur J Clin Microbiol Infect Dis. 2012;31:481-6 pubmed publisher
    ..pneumoniae ST23 strains, which are closely related to liver abscess isolates. Differences in carriage rates by country of residence suggests that environmental factors might play an important role in the carriage of this strain...
  8. Peppoloni S, Ricci S, Orsi C, Colombari B, de Santi M, Messinò M, et al. The encapsulated strain TIGR4 of Streptococcus pneumoniae is phagocytosed but is resistant to intracellular killing by mouse microglia. Microbes Infect. 2010;12:990-1001 pubmed publisher
    ..The results indicate that encapsulation does not protect the TIGR4 strain from phagocytosis by microglia, while it affords resistance to intracellular killing. ..
  9. Fevre C, Passet V, Deletoile A, Barbe V, Frangeul L, Almeida A, et al. PCR-based identification of Klebsiella pneumoniae subsp. rhinoscleromatis, the agent of rhinoscleroma. PLoS Negl Trop Dis. 2011;5:e1052 pubmed publisher
    ..This work provides rapid and simple molecular tools to confirm the diagnostic of rhinoscleroma, which should improve patient care as well as knowledge on the prevalence and epidemiology of rhinoscleroma...

More Information


  1. Wang K, Fan W, Cai L, Huang B, Lu C. Genetic analysis of the capsular polysaccharide synthesis locus in 15 Streptococcus suis serotypes. FEMS Microbiol Lett. 2011;324:117-24 pubmed publisher
    ..The characteristics of the CPS synthesis locus suggest that some genes may have been imported into S. suis (or their ancestors) on multiple occasions from different and unknown sources. ..
  2. Nakhamchik A, Wilde C, Chong H, Rowe Magnus D. Evidence for the horizontal transfer of an unusual capsular polysaccharide biosynthesis locus in marine bacteria. Infect Immun. 2010;78:5214-22 pubmed publisher
    ..Furthermore, several of the encoded proteins appeared to be of Gram-positive and archaebacterial origin. These data indicate that the horizontal transfer of intact and partial CPS loci drives CPS diversity in marine bacteria. ..
  3. Salter S, Hinds J, Gould K, Lambertsen L, Hanage W, Antonio M, et al. Variation at the capsule locus, cps, of mistyped and non-typable Streptococcus pneumoniae isolates. Microbiology. 2012;158:1560-9 pubmed publisher
    ..These data provide greater understanding of diversity at a locus which is crucial to the antigenic diversity of the pathogen and current vaccine strategies. ..
  4. Melin M, Trzcinski K, Meri S, Kayhty H, Vakevainen M. The capsular serotype of Streptococcus pneumoniae is more important than the genetic background for resistance to complement. Infect Immun. 2010;78:5262-70 pubmed publisher
    ..Differences between serotypes were more significant than the differences between strains. ..
  5. Sørensen M, van Alphen L, Harboe A, Li J, Christensen B, Szymanski C, et al. Bacteriophage F336 recognizes the capsular phosphoramidate modification of Campylobacter jejuni NCTC11168. J Bacteriol. 2011;193:6742-9 pubmed publisher
    ..In summary, we have identified the phase-variable MeOPN moiety, a common component of the diverse capsular polysaccharides of C. jejuni, as a novel receptor of phages infecting this bacterium. ..
  6. Soliakov A, Harris J, Watkinson A, Lakey J. The structure of Yersinia pestis Caf1 polymer in free and adjuvant bound states. Vaccine. 2010;28:5746-54 pubmed publisher
    ..We also provide the first images of proteins bound to alhydrogel adjuvant. Caf1, hemocyanin and anthrax PA are all resolved clearly and Caf1 exhibits adjuvant bound stretches with long intervening loops draped from the edges. ..
  7. Ho J, Lin T, Li C, Lee A, Cheng A, Chen M, et al. Functions of some capsular polysaccharide biosynthetic genes in Klebsiella pneumoniae NTUH K-2044. PLoS ONE. 2011;6:e21664 pubmed publisher
    ..Taken together, the results suggest that kp3706, kp3709 or kp3712 genes are strongly related to the pathogenesis of K. pneumoniae K1. ..
  8. Hollanda L, Cury G, Pereira R, Ferreira G, Sousa A, Sousa E, et al. Effect of mesoporous silica under Neisseria meningitidis transformation process: environmental effects under meningococci transformation. J Nanobiotechnology. 2011;9:28 pubmed publisher
    ..the mesouporous silica particles were capable of increasing the capsule replacement frequency in N. meningitidis. ..
  9. Singh A, Wyant T, Anaya Bergman C, Aduse Opoku J, Brunner J, Laine M, et al. The capsule of Porphyromonas gingivalis leads to a reduction in the host inflammatory response, evasion of phagocytosis, and increase in virulence. Infect Immun. 2011;79:4533-42 pubmed publisher
    ..As such, it is a major virulence determinant of P. gingivalis. ..
  10. Elberse K, Van de Pol I, Witteveen S, van der Heide H, Schot C, van Dijk A, et al. Population structure of invasive Streptococcus pneumoniae in The Netherlands in the pre-vaccination era assessed by MLVA and capsular sequence typing. PLoS ONE. 2011;6:e20390 pubmed publisher
    ..MLVA and CST appear to be valuable tools to determine the population structure of pneumococcal isolates and are useful in monitoring the effects of pneumococcal vaccination. ..
  11. Donkor E, Bishop C, Gould K, Hinds J, Antonio M, Wren B, et al. High levels of recombination among Streptococcus pneumoniae isolates from the Gambia. MBio. 2011;2:e00040-11 pubmed publisher
    ..This could have consequences for the population response to conjugate vaccination...
  12. Henriques M, Rodrigues T, Carido M, Ferreira L, Filipe S. Synthesis of capsular polysaccharide at the division septum of Streptococcus pneumoniae is dependent on a bacterial tyrosine kinase. Mol Microbiol. 2011;82:515-34 pubmed publisher
  13. Carvalho S, Kuipers O, Neves A. Environmental and nutritional factors that affect growth and metabolism of the pneumococcal serotype 2 strain D39 and its nonencapsulated derivative strain R6. PLoS ONE. 2013;8:e58492 pubmed publisher
    ..These results represent the first metabolic profiling data obtained non-invasively for S. pneumoniae, and pave the way to a better understanding of regulation of central metabolism. ..
  14. Weening E, Cathelyn J, Kaufman G, Lawrenz M, Price P, Goldman W, et al. The dependence of the Yersinia pestis capsule on pathogenesis is influenced by the mouse background. Infect Immun. 2011;79:644-52 pubmed publisher
    ..pestis is dependent on the genetic makeup of its host and provides further support for the hypothesis that PsaA and Caf1 have different targets. ..
  15. Sheppard C, Pichon B, George R, Hall L. Streptococcus pneumoniae isolates expressing a capsule with epitopes of both serotypes 6A and 6B. Clin Vaccine Immunol. 2010;17:1820-2 pubmed publisher
    ..This finding highlights that mutation as well as recombination can mediate serotype change. ..
  16. Lecours M, Fittipaldi N, Takamatsu D, Okura M, Segura M, Goyette Desjardins G, et al. Sialylation of Streptococcus suis serotype 2 is essential for capsule expression but is not responsible for the main capsular epitope. Microbes Infect. 2012;14:941-50 pubmed publisher
    ..Together, our results infer that sialylation of S. suis serotype 2 may be essential for capsule expression, but that this sugar is not the main epitope of this serotype. ..
  17. Calix J, Nahm M. A new pneumococcal serotype, 11E, has a variably inactivated wcjE gene. J Infect Dis. 2010;202:29-38 pubmed publisher
    ..We propose to name the 11Aalpha subtype as serotype 11A and the 11Abeta subtype as 11E, a new serotype. Our findings also suggest that the diversity of pneumococcal capsules is much greater than was previously recognized. ..
  18. Hsieh P, Lin T, Yang F, Wu M, Pan Y, Wu S, et al. Lipopolysaccharide O1 antigen contributes to the virulence in Klebsiella pneumoniae causing pyogenic liver abscess. PLoS ONE. 2012;7:e33155 pubmed publisher
  19. Gupta M, Kumar R, Deb A, Bhattacharya S, Bose A, John J, et al. Multi-center surveillance for pneumonia & meningitis among children (<2 yr) for Hib vaccine probe trial preparation in India. Indian J Med Res. 2010;131:649-58 pubmed
    ..There is a significant burden of pneumonia and meningitis among children in India. Continued strengthening of laboratory capacity and bacterial surveillance systems are necessary. ..
  20. Wu M, Lin T, Hsieh P, Yang H, Wang J. Isolation of genes involved in biofilm formation of a Klebsiella pneumoniae strain causing pyogenic liver abscess. PLoS ONE. 2011;6:e23500 pubmed publisher
    ..The importance of treC in gastrointestinal tract colonization suggests that biofilm formation contributes to the establishment and persistence of K. pneumoniae infection. ..
  21. Bostanci N, Belibasakis G. Porphyromonas gingivalis: an invasive and evasive opportunistic oral pathogen. FEMS Microbiol Lett. 2012;333:1-9 pubmed publisher
    ..Moreover, the role of P. gingivalis as a 'keystone' biofilm species in orchestrating a host response, is highlighted...
  22. Jimenez N, Senchenkova S, Knirel Y, Pieretti G, Corsaro M, Aquilini E, et al. Effects of lipopolysaccharide biosynthesis mutations on K1 polysaccharide association with the Escherichia coli cell surface. J Bacteriol. 2012;194:3356-67 pubmed publisher
    ..These results suggest that the K1 polysaccharide remains cell associated by ionically interacting with the phosphate-negative charges of the core LPS. ..
  23. Wang K, Fan W, Wisselink H, Lu C. The cps locus of Streptococcus suis serotype 16: development of a serotype-specific PCR assay. Vet Microbiol. 2011;153:403-6 pubmed publisher
    ..Primers based on cps16G were used to develop a serotype 16 specific PCR. The PCR assay was successfully used to identify S. suis serotype 16 in the 99 Chinese S. suis clinical isolates and 8 European isolates. ..
  24. Heiss C, Burtnick M, Wang Z, Azadi P, Brett P. Structural analysis of capsular polysaccharides expressed by Burkholderia mallei and Burkholderia pseudomallei. Carbohydr Res. 2012;349:90-4 pubmed publisher
    ..mallei to express a 6-deoxy-heptan CPS and represents the first report of a mannan CPS being expressed by these bacterial pathogens...
  25. Lecours M, Segura M, Lachance C, Mussá T, Surprenant C, Montoya M, et al. Characterization of porcine dendritic cell response to Streptococcus suis. Vet Res. 2011;42:72 pubmed publisher
    ..suis interacts with swine origin DCs and suggest that these cells might play a role in the development of host innate and adaptive immunity during an infection with S. suis serotype 2. ..
  26. Hsu C, Lin T, Chen Y, Chou H, Wang J. The role of Klebsiella pneumoniae rmpA in capsular polysaccharide synthesis and virulence revisited. Microbiology. 2011;157:3446-57 pubmed publisher
    ..We found an association of p-rmpA with three widely spaced loci in a large plasmid (30/32). Therefore, rmpA could be co-inherited together with virulence genes carried by this plasmid. ..
  27. Ojo L, O Loughlin R, Cohen A, Loo J, Edmond K, Shetty S, et al. Global use of Haemophilus influenzae type b conjugate vaccine. Vaccine. 2010;28:7117-22 pubmed publisher
    ..Additional efforts are still needed to increase vaccine adoption in lower middle income countries [20/31 (65%) by the end of 2009]. ..
  28. Sathiyamoorthy K, Mills E, Franzmann T, Rosenshine I, Saper M. The crystal structure of Escherichia coli group 4 capsule protein GfcC reveals a domain organization resembling that of Wza. Biochemistry. 2011;50:5465-76 pubmed publisher
    ..Finally, we draw analogies between a GfcC protein fused to an outer membrane ?-barrel pore in some species and fusion proteins necessary for secreting biofilm-forming exopolysaccharides. ..
  29. Elberse K, Witteveen S, van der Heide H, Van de Pol I, Schot C, van der Ende A, et al. Sequence diversity within the capsular genes of Streptococcus pneumoniae serogroup 6 and 19. PLoS ONE. 2011;6:e25018 pubmed publisher
    ..Such changes may result in altered polysaccharides or in strains that produce more capsular polysaccharides. Consequently, these altered capsules may be less sensitive for vaccine induced immunity. ..
  30. Hathaway L, Brugger S, Morand B, Bangert M, Rotzetter J, Hauser C, et al. Capsule type of Streptococcus pneumoniae determines growth phenotype. PLoS Pathog. 2012;8:e1002574 pubmed publisher
    ..pneumoniae interferes with growth in nutrient-limiting conditions probably by competition for energy against the central metabolism. Serotype-specific nasopharyngeal carriage prevalence in vivo is predicted by the growth phenotype. ..
  31. Willis L, Whitfield C. KpsC and KpsS are retaining 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) transferases involved in synthesis of bacterial capsules. Proc Natl Acad Sci U S A. 2013;110:20753-8 pubmed publisher
    ..KpsS adds the first Kdo residue, and this reaction product is then extended by KpsC. Cross-complementation experiments demonstrate that the E. coli and N. meningitidis protein homologs are functionally conserved. ..
  32. Wang Q, Shao Z, Wang X, Gao Y, Li M, Xu L, et al. Genetic study of capsular switching between Neisseria meningitidis sequence type 7 serogroup A and C strains. Infect Immun. 2010;78:3883-8 pubmed publisher
  33. Pan P, Chen H, Wu P, Wu Y, Lin C, Wu J. Mutation in fucose synthesis gene of Klebsiella pneumoniae affects capsule composition and virulence in mice. Exp Biol Med (Maywood). 2011;236:219-26 pubmed publisher
    ..The results indicate that disruption of the fucose synthesis gene affected the pathophysiology of this bacterium and may be related to the virulence of this KpL1 strain...
  34. Kim D, Han K, Oh Y, Kim C, Kang I, Lee J, et al. Distribution of capsular serotypes and virulence markers of Streptococcus suis isolated from pigs with polyserositis in Korea. Can J Vet Res. 2010;74:314-6 pubmed
    ..All 24 isolates carried the sly gene. The serotype and genotype distribution greatly differed from that reported for isolates from pigs with other clinical manifestations of S. suis infection in other countries...
  35. Melin M, Trzcinski K, Antonio M, Meri S, Adegbola R, Kaijalainen T, et al. Serotype-related variation in susceptibility to complement deposition and opsonophagocytosis among clinical isolates of Streptococcus pneumoniae. Infect Immun. 2010;78:5252-61 pubmed publisher
  36. Lin T, Yang F, Yang A, Peng H, Li T, Tsai M, et al. Amino acid substitutions of MagA in Klebsiella pneumoniae affect the biosynthesis of the capsular polysaccharide. PLoS ONE. 2012;7:e46783 pubmed publisher
    ..pneumoniae NTUH-K2044, capsular type K1. These amino acids are also likely to be important for the function of Wzy in other capsular types in K. pneumoniae and other species bearing Wzy_C family proteins. ..
  37. Lecours M, Gottschalk M, Houde M, Lemire P, Fittipaldi N, Segura M. Critical role for Streptococcus suis cell wall modifications and suilysin in resistance to complement-dependent killing by dendritic cells. J Infect Dis. 2011;204:919-29 pubmed publisher
    ..suis hemolysin was partially involved in cytokine release and also contributed to bacterial escape of opsonophagocytosis. Overall, S. suis uses its arsenal of virulence factors to modulate DC functions and escape immune surveillance. ..
  38. Van Calsteren M, Gagnon F, Lacouture S, Fittipaldi N, Gottschalk M. Structure determination of Streptococcus suis serotype 2 capsular polysaccharide. Biochem Cell Biol. 2010;88:513-25 pubmed publisher
    ..A correlation between the S. suis CPS sequence and genes of the serotype 2 cps locus encoding putative enzymes responsible for the biosynthesis of the repeating unit was tentatively established. ..
  39. Creti R, Imperi M, Pataracchia M, Alfarone G, Recchia S, Baldassarri L. Identification and molecular characterization of a S. agalactiae strain lacking the capsular locus. Eur J Clin Microbiol Infect Dis. 2012;31:233-5 pubmed publisher
    ..Such an event, while possibly a dead-end from the evolutionary point of view, leaves a still able-to-colonize organism unrecognizable by the vaccines currently under development. ..
  40. Byrne J, Morona J, Paton J, Morona R. Identification of Streptococcus pneumoniae Cps2C residues that affect capsular polysaccharide polymerization, cell wall ligation, and Cps2D phosphorylation. J Bacteriol. 2011;193:2341-6 pubmed publisher
    ..The introduced mutations affect either polymerization or ligation of CPS to the cell wall and/or Cps2D phosphorylation. ..
  41. Trappetti C, Ogunniyi A, Oggioni M, Paton J. Extracellular matrix formation enhances the ability of Streptococcus pneumoniae to cause invasive disease. PLoS ONE. 2011;6:e19844 pubmed publisher
    ..We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease. ..
  42. Hsu C, Lin T, Pan Y, Hsieh P, Wang J. Isolation of a bacteriophage specific for a new capsular type of Klebsiella pneumoniae and characterization of its polysaccharide depolymerase. PLoS ONE. 2013;8:e70092 pubmed publisher
    ..The capsular polysaccharide (CPS) is an important virulence factor of K. pneumoniae. With 78 capsular types discovered thus far, an association between capsular type and the pathogenicity of K. pneumoniae has been observed...
  43. Okura M, Takamatsu D, Maruyama F, Nozawa T, Nakagawa I, Osaki M, et al. Genetic analysis of capsular polysaccharide synthesis gene clusters from all serotypes of Streptococcus suis: potential mechanisms for generation of capsular variation. Appl Environ Microbiol. 2013;79:2796-806 pubmed publisher
    ..Accumulation of these gene transfers and small-scale mutations may have generated the antigenic diversity of S. suis CPs. ..
  44. Hiller N, Eutsey R, Powell E, Earl J, Janto B, Martin D, et al. Differences in genotype and virulence among four multidrug-resistant Streptococcus pneumoniae isolates belonging to the PMEN1 clone. PLoS ONE. 2011;6:e28850 pubmed publisher
  45. Nadler C, Koby S, Peleg A, Johnson A, Suddala K, Sathiyamoorthy K, et al. Cycling of Etk and Etp phosphorylation states is involved in formation of group 4 capsule by Escherichia coli. PLoS ONE. 2012;7:e37984 pubmed publisher
    ..These results suggest that cycles of phosphorylation and dephosphorylation of Etp, as well as Etk, are involved in the formation of group 4 capsule, providing an additional regulatory layer to the complex control of capsule production. ..
  46. Hu F, Eutsey R, Ahmed A, Frazão N, Powell E, Hiller N, et al. In vivo capsular switch in Streptococcus pneumoniae--analysis by whole genome sequencing. PLoS ONE. 2012;7:e47983 pubmed publisher
    ..The nature of this determinants remains to be identified. ..
  47. Yother J. Capsules of Streptococcus pneumoniae and other bacteria: paradigms for polysaccharide biosynthesis and regulation. Annu Rev Microbiol. 2011;65:563-81 pubmed publisher
    ..Characterization of these systems has provided novel insights that are applicable to polymers synthesized by many gram-positive and gram-negative bacteria, as well as eukaryotes. ..
  48. Stollerman G, Dale J. The importance of the group a streptococcus capsule in the pathogenesis of human infections: a historical perspective. Clin Infect Dis. 2008;46:1038-45 pubmed publisher
    ..We believe that it is time to refocus newer clinical studies and techniques on achieving early recognition of potentially dangerous, heavily encapsulated strains of GAS for which spread may be prevented. ..
  49. Ku Y, Chuang Y, Yu W. Clinical spectrum and molecular characteristics of Klebsiella pneumoniae causing community-acquired extrahepatic abscess. J Microbiol Immunol Infect. 2008;41:311-7 pubmed
    ..This study investigated the clinical spectrum and molecular characteristics of community-acquired Klebsiella infection with primary extrahepatic abscess...
  50. Bratcher P, Park I, Hollingshead S, Nahm M. Production of a unique pneumococcal capsule serotype belonging to serogroup 6. Microbiology. 2009;155:576-83 pubmed publisher
    ..Nevertheless, this study shows that this capsular PS is biochemically possible and could exist/emerge in nature. ..
  51. Yu W, Ko W, Cheng K, Lee C, Lai C, Chuang Y. Comparison of prevalence of virulence factors for Klebsiella pneumoniae liver abscesses between isolates with capsular K1/K2 and non-K1/K2 serotypes. Diagn Microbiol Infect Dis. 2008;62:1-6 pubmed publisher
    ..Without significant difference in the prevalence of expressing hypermucoviscosity phenotype and carriage of rmpA and aerobactin genes, these virulent non-K1/K2 isolates are as capable as K1/K2 isolates of causing primary liver abscesses...
  52. Kugelberg E, Gollan B, Farrance C, Bratcher H, Lucidarme J, Ibarz Pavón A, et al. The influence of IS1301 in the capsule biosynthesis locus on meningococcal carriage and disease. PLoS ONE. 2010;5:e9413 pubmed publisher
    ..Novel polymorphisms associated with IS1301 in the IGR of UK MenB isolates do not lead to the resistance phenotype seen for IS1301 in the IGR of MenC isolates. ..
  53. Lin M, Hsu T, Lin S, Pan Y, Jan J, Wang J, et al. Phosphoproteomics of Klebsiella pneumoniae NTUH-K2044 reveals a tight link between tyrosine phosphorylation and virulence. Mol Cell Proteomics. 2009;8:2613-23 pubmed publisher
    ..Our study provided a clear trend that WcaJ tyrosine phosphorylation can regulate the biosynthesis of capsular polysaccharides and result in the pathogenicity of K. pneumoniae NTUH-K2044. ..