Columbia agar plate

The S. mediterranea asexual clonal line ClW4^{24 (link)} was maintained at 18 °C in water. The water was first filtered through charcoal and ceramics with pores of 0.2 µm (manufactured by Fairey Industrial Ceramics Limited) and through a membrane of 0.2 µm (Thermo Scientific Nalgene Filtration Products) for 10 years. Microbiological analysis of the filtered water was performed by inoculation of 5% sheep blood-enriched Columbia agar plates (bioMérieux, Marcy l’étoile, France) with 25, 50, or 100 µL of filtered water. Inoculated plates were then incubated at 19, 28, or 37 °C for 4 days. Any bacteria were detected.S. mediterranea were fed once per week with homogenized calf liver (batch 20118-5814, origin: Saprimex (a local supermarket), 13310 St Martin de Crau) and then starved 2 weeks prior to experiments. In some experiments, worms were starved for 1 or 4 weeks. The bacterial constituents of homogenized calf liver were defined by inoculation of 5% sheep blood-enriched Columbia agar plates (bioMérieux, Marcy l’étoile, France) with 25, 50, or 100 µL of homogenized calf liver. Inoculated plates were then incubated at 19, 28, or 37 °C for 1, 2, 3, and 4 days.

For the synthesis of the microgels: N-isopropylacrylamide (NIPAM, 99%) and 2-(dimethylamino)ethyl methacrylate (DMAEMA, 98%, Aldrich, St. Quentin Fallavier, France) were used as monomers. N,N’-Methylenbis(acrylamide) (MBA, Aldrich), was used as the crosslinking agent and ammonium persulfate (APS, Aldrich) was the initiator of the reaction. Iodomethane (Aldrich, 99%) and 1-iodobutane (Aldrich, 99%) were employed as the alkylating agent. Anhydrous dimethylformamide (DMF) (99.5% purity) and hexane (95%) was supplied by Sigma Aldrich, as used as received.
For the microbiological assays: Sodium chloride (NaCl, 0.9%, BioXtra, Steinheim, Germany, suitable for cell cultures) and phosphate buffered saline (PBS, pH 7.4) were purchased from Aldrich. The microbial growth media, BBL^TM Mueller Hinton broth was obtained from Becton, Dickinson and Company (Madrid, Spain). Sheep blood (5%) Columbia Agar plates were acquired from BioMérieux (Madrid, Spain). Gram-positive Staphylococcus aureus (S. aureus, ATCC 29213) and Staphylococcus epidermidis (S. epidermidis, ATCC 12228), were used as bacterial strains, and the yeast Candida parapsilosis (C. parapsilosis, ATCC 22109) was used as fungal strain and purchased from Oxoid (Wesel, Germany).

The acrystalliferous B. thuringiensis 407 Cry^- strain (Bt 407^-; Lereclus et al., 1989 (link)) was used as the parental strain to create all the strains used in this study. Escherichia coli strain DH5α (Taylor et al., 1993 (link)) was used as the host strain for plasmid construction. E. coli strain ET12567 (MacNeil et al., 1992 (link)) was used to prepare DNA prior to electroporation in B. thuringiensis. Unless otherwise noted, cells were grown in LB medium (1% tryptone, 0.5% yeast extract, 1% NaCl) at 37°C and stored at -80°C in LB containing 15% glycerol.
For B. thuringiensis cultures, t0 corresponds to the beginning of the transition between the exponential and stationary growth phases. It is defined as the point where the slope starts to decrease at the end of the exponential phase.
Columbia agar plates (BioMérieux) containing 5% sheep blood were used to evaluate the hemolytic activity of the B. thuringiensis strains. BHI (Beckton-Dickinson) agar plates containing 5% egg yolk were used to evaluate the lecithinase activity of the B. thuringiensis strains.
The antibiotic concentrations used for selection of B. thuringiensis and E. coli were as follows: erythromycin, 10 μg/mL; kanamycin, 200 μg/mL; ampicillin, 100 μg/mL.
When required, xylose was used at a concentration of 20 mM.