Listeria innocua

Two market wood pulps, southern bleached softwood kraft (SBSK) and southern unbleached softwood kraft (UBSK) pulp from a paper mill in the Southeast United States were used for the formation of paper samples.
Two microbial strains, Salmonella enterica serotype Typhimurium MHM 124 (ATCC 14208) and Listeria innocua (ATCC 51742), were received as freeze-dried samples from the American Type Culture Collection (ATCC). Trypticase soy broth (TSB) and trypticase soy agar (TSA) were used for overnight cultures incubated at 37°C for both bacterial strains (Fisher Scientific, Waltham, MA, USA). Additional growth factors including dextrose, ammonium iron (III) citrate and anhydrous magnesium sulfate were acquired as well from Fisher Scientific (Waltham, MA, USA).

The bacterial strain used for SELEX selection was P. aeruginosa 692 (PA692) (ATCC 14502) obtained from New Zealand Culture Collection (Porirua, NZ). Other bacterial strains used were: P.aeruginosa PAO1 (ATCC 15692), Salmonella enterica serovar Typhi (ATCC 19430), Klebsiella pneumoniae (ATCC 13883), Enterobacter cloacae (ATCC 13047), Listeria innocua (ATCC 33090) and Escherichia coli DH5α. Additional P. aeruginosa strains used in binding studies were clinical isolates PA1024 (catheter, urine), PA1205 (left thigh), PA1323 (cystic fibrosis sputum), PA1079 (tracheal aspirate), and PA1236 (blood) obtained from Environmental Science and Research Culture Collection (Porirua, NZ). All bacterial strains were cultured in standard Luria Broth (LB) medium at 37°C for 16 hours with aeration. After growth, the cells were diluted 1:100 in fresh LB and grown for 4 hours to allow them to reach exponential phase.

Nine test strains and one internal standard strain were used. The following test strains were obtained from the American Type Culture Collection (ATCC); Kocuria rhizophila (ATCC 9341), Escherichia coli (ATCC 33588), Enterococcus hirae (ATCC 8043), Bacillus subtilis (ATCC 6051), Enterococcus faecalis (ATCC 47077), Streptococcus mutans (ATCC 25175), Listeria innocua (ATCC33090), and Staphylococcus epidermidis (ATCC12228). Ralstonia solanacearum (T-11 strain) [20 ] was isolated from Tomato plants. Lactobacillus sakei (NBRC 15893) used for internal standard was obtained from the National Institute of Technology and Evaluation (NBRC). All these strains were cultured in a BD Difco Nutrient broth supplemented with 5 g/L yeast extract (NYB).