బయోటెక్నాలజీ & బయోమెటీరియల్స్

నైరూప్య

Chitin Nanowhiskers Mediate Transformation of Escherichia coli by Exogenous Plasmid DNA

Alisa Mera, Jun Araki, Takashi Ohtsuki, Makoto Shimosaka and Naoto Yoshida

A colloidal solution of chitin nanowhiskers containing pUC18 plasmid DNA and cells of Escherichia coli was placed on an agar hydrogel and stimulated by sliding friction applied between the agar hydrogel and polystyrene stir stick, leading to transformation of the bacteria to antibiotic resistance. The combination of chitin nanowhiskers and sliding friction was necessary for genetic transformation, indicating that the chitin nanowhiskers induced the Yoshida effect, resulting in the formation of E. coli cells penetration-intermediates. The pUC18 adsorbed onto the chitin nanowhiskers is presumably taken up through the penetration-intermediates, leading to transformation. The transformation efficiency changed when the number of recipient cells and amount of chitin nanowhiskers were varied. The maximum number of penetration-intermediates acquiring pUC18 DNA was obtained with concentrations of agar hydrogel, chitin nanowhiskers, and recipient E. coli cells of 2.5%, 5.0 ?g/ml, and 4.8 x 108 cells/ml, respectively. Optimal transformation efficiency with pUC18 was achieved with 2.1 x 1066 colony forming units/?g of pUC18. Induction of the Yoshida effect with chitin nanowhiskers represents a simpler alternative for introducing genes into bacteria.