Generation of chitin-derived oligosaccharides toxic to pathogenic bacteria using ChiA74, an endochitinase native to Bacillus thuringiensis.
OBJECTIVE
To demonstrate that an endochitinase (ChiA74) native to Bacillus thuringiensis can be used to generate chitin-derived oligosaccharides (OGS) with antibacterial activity against a number of aetiological agents of disease, including bacteria that cause diarrhoeal and emetic syndromes in humans.


RESULTS
The intact chiA74 with its cis elements was cloned into high and moderately high copy number Escherichia coli expression vectors. Functionally secreted ChiA74 was produced, and the endochitinase cleaved substrate colloidal chitin to produce OGS with 3, 5 and 6 degrees of polymerization. The enzyme was active for an extended period of incubation (24 h), but its activity showed a decrement of 73% and 87%, respectively, after 24 h of incubation at 37 and 55 degrees C. OGS showed inhibitory activity against Bacillus cereus, Listeria inoccua, E. coli, Staphylococcus xylosus, Salmonella species, Staphylococcus aureus, Pseudomona aeruginosa, Shigella flexneri, and Proteus vulgaris.


CONCLUSIONS
Endochitinase ChiA74 is able to stably maintain hydrolytic activity during prolonged incubation in a mix reaction with chitin to produce bioactive OGS with inhibitory activity against important food-borne pathogenic bacteria.


CONCLUSIONS
This is the first study showing that an endochitinase (ChiA74) native of the most important bioinsecticide used worldwide (B. thuringiensis), but here produced in E. coli, is able to generate chitin-derived OGS with antibacterial activity against clinically significant food-borne pathogenic bacteria.
Ortiz-Rodríguez
T
T
Universidad de Guanajuato Campus Irapuato-Salamanca, División Ciencias de la Vida, Departamento de Ingeniería en Alimentos, Irapuato, Guanajuato, México.
de la Fuente-Salcido
N
N
Bideshi
D K
DK
Salcedo-Hernández
R
R
Barboza-Corona
J E
JE
D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D001413:Bacillus thuringiensis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000378:metabolism; D002686:Chitin / Q000378:metabolism*; D002688:Chitinases / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009844:Oligosaccharides / Q000378:metabolism* / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D009844:Oligosaccharides; D011994:Recombinant Proteins; D002686:Chitin; D002688:Chitinases