PSEUDOMONAS CEPACIA ADAPTABILITY 199 measured (in mm) to the point of inhibition. The Minimum Inhibitory Concentration, MIC value, for a particular preservative is determined by using the dilution plate which exhibits a measurable (30 to 50 mm) growth front. MIC values are obtained by a direct proportion of the Gradient Plate concentration of preservative to the growth front measurement (exemplified in Figure 2). RESULTS AND DISCUSSION 1. ENUMERATION OF PROTOTYPE CONTAMINANTS Plate counts had shown a contamination level of 105 cells/g product. 2. API EVALUATION The API © 20E biochemical reactions could be read accurately only after 36 to 48 hours incubation of the test strips. It is suggested that a 9 digit number be employed when biochemical reactions are determined after a 48 hour incubation of strips. However, only an 8 digit number was determined i.e., growth on MacConkey's and tests for the Oxidative/Fermentive Utilization of Glucose (tubes not available) were not completed. Colonies, which had been isolated from Tryptic Soy Agar plates, were evaluated from the unpreserved, and from the formaldehyde (100 ppm) and benzoic acid (200 ppm) containing formulas. To determine whether the organism's biochemical reactions would change after it had been isolated from its hostile environment, an API evaluation was completed after each of 10 consecutive transfers for both the unpreserved and the formaldehyde resistant organisms. As shown in Table I, the reactions were remarkably consistent. Positive reactions were ONPG (O-nitrophenyl-•-d-galactoside), citrate utilization, glucose fermentation, and nitrate reduction. Arabinose fermentation was frequently positive, and amygdalin fermentation was only occasionally positive. The organism appeared to be oxidase-positive, but the reaction took from 10 seconds to 5 minutes. Although an Oxidase Test is commonly read in 10 seconds, this organism gave atypical results (indicated as _+ in Table I). The organism was found to be motile and beige-yellow in color on both Tryptic Soy and Pseudomonas Isolation Agar plates. The profile index numbers identified the organism, from both the unpreserved and preserved formulations, as "acceptable" to "very good" identification for P. cepacia. 3. CONTAMINATED PRODUCT TREATMENT Replicate samples of contaminated product containing various concentrations of formaldehyde or benzoic acid were prepared. As shown in Figure 1, the organisms were eliminated (sterility in a 10 g sample) in less than a week, by 300 ppm formaldehyde, or 400 ppm benzoic acid concentration. The sample with 300 ppm benzoic acid continued to show bactericidal activity at a slower rate. In contrast, the sample with 200 ppm of formaldehyde exhibited initial activity (dropping the count to 10/g), but the organisms grew out to the original level within a relatively short time. To determine whether this organism, which had adapted rather quickly to a 100 ppm

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