Case Study: Decreasing Time for Mold Detection by 50%
Challenge: Many companies have microbial specifications for their products based on the USP guidelines, product history, and risk. When
it comes to mold, this usually means being able to detect Aspergillus niger. This mold's slow growth is therefore typically the rate-determining step for product release. Additional requirements can
make the process take even longer. One major pharmaceutical and personal-care products company manufactured products which
required the detection of Penicillium expansum. This company was using standard bioluminescence (48-hour detection), however the restricted mold specification required
an additional day of incubation—a time-to-release the company considered unacceptable.
Solution: Celsis worked with the company to modify their existing bioluminescence protocol to decrease their time to result without
jeopardizing product quality. A study was performed on a water-based lotion for babies. Celsis examined how broth type, incubation
temperature and conditions affect A. niger and P. expansum detection using both standard bioluminescence and AKuScreen reagents.
Table I: Results of Case Study 1, Decreasing Time for Mold Detection by 50%
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Preliminary studies indicated that static incubation at room temperature optimizes the growth of P. expansum. The table below summarizes the study data. All samples were inoculated with <50 spores of P. expansum and incubated statically at room temperature (24–27° C). (See Table I)
This amplification allows for greater differentiation and a more sensitive measure of microbial contamination. Therefore,
companies can more effectively screen products with elevated background of non-microbial ATP and products contaminated with
adaptive, slow growing organisms. Also, the time to result is reduced to 18-24 hours compared to 24-48 hours with standard
ATP bioluminescence and 3-5 days with traditional methods.
Case study: Detection of Slow-Growing Microorganisms
Challenge: A large consumer products company faced a contamination event with a fabric softener that had a pH of 4.0. Microorganisms
can adapt to chemically hostile products such as these. Product-adapted microorganisms are usually fastidious and slow-growing,
making it difficult to detect using traditional agar or standard bioluminescence methods. Following a prolonged incubation,
the contaminating microorganism was isolated and identified as Acetobacter pasteurianus.
Solution: The manufacturer contacted Celsis for assistance in exploring the potential for testing its fabric softener product using
ATP bioluminescence. The goal was to provide faster detection and faster correction of future contamination events. Although
the Celsis bioluminescence technology is designed for the rapid detection of microorganisms, in order to detect low levels
of contaminants an enrichment step is required to ensure that there is sufficient ATP present for detection. The majority
of culture media are prepared with a final neutral pH of 7.2 ± 2. Acidophiles such as A. pasteurianus prefer a pH of less
than 5.4.
In order to detect microorganisms in low pH products using ATP bioluminescence, two studies were performed at Celsis to determine
the optimal enrichment medium and whether AKuScreen could be used to detect artificial and naturally contaminated product
in order to release product in the shortest amount of time.
Study 1: Broth Optimization
Table II: Case Study 2, Study I, Broth Optimization
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Five different fabric softeners were tested with three different broth types (Letheen, TAT and Sabouraurd Dextrose Broth).
The product-broth suspensions were spiked with <10 cells of Acetobacter sp. and tested at 24, 48 and 72 hours using standard
bioluminescence reagents.(See Table II)
The data indicates that Sabouraud Dextose broth (SDB) is the optimum broth for growth and detection of Acetobacter species.
SDB was able to detect the product-adapted microorganism in all five fabric softener products within 72 hours using standard
bioluminescence.
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