Your plate met room air an hour ago. Will it still recover your organism?
A controlled study across five Brucella agars shows how a plate’s oxygen protection strategy determines strict anaerobe recovery after routine benchtop handling, and how much recovery active protection preserves.
Oxygen Exposure Survival of a Strict Anaerobe on Protected and Unprotected Brucella Agars
Every minute on the bench costs recovery
Strict anaerobes begin to lose viability the moment their culture plates meet room air, and in a working laboratory that exposure is unavoidable. Plates are unpackaged, set out, examined, and moved on an open bench, and increasingly they are fed through automated streaking instruments that hold each plate in open air.
By the time a fragile anaerobe is streaked onto that surface, the agar may already be too oxidized to recover it. A colony that never forms reads as a negative culture: a missed pathogen, a repeat collection, and an incomplete picture for therapy and stewardship.
The one variable you control
Technique and speed help, but they are the hardest things to hold constant across every shift, technologist, and automated run. The medium is different. It is a single decision, made at purchasing, that sets the ceiling on how much benchtop exposure a plate can absorb before recovery suffers.
This white paper measures where that ceiling sits for five common approaches, from no protection to active enzymatic oxygen scavenging, using one clean experiment.
What you’ll take away
A practical, data-backed answer to a question every anaerobic lab faces, written for lab directors, clinical microbiologists, and the teams that choose media.
- The protection gradient explained. How post-reduction, anaerobic packaging, PRAS manufacture, and active enzymatic scavenging actually differ, and why the label rarely tells you.
- Recovery data at five exposure intervals. Absolute counts and survival versus baseline for each medium from 0 to 3 hours of open-air exposure.
- The difference on the plate. Side-by-side plate images showing recovery lost to oxygen at 2 hours.
- What it means for automated streaking. Why a fixed exposure window makes media selection matter more, not less, on high-throughput platforms.
- A practical checklist. Five steps to match your medium to your real bench exposure.
- Full methods and scope. Transparent design, replicate counts, and limitations so you can weigh the evidence yourself.
A clean test, plainly reported
One variable isolated
Every medium shares the same Brucella agar nutrient base, so differences in recovery reflect oxygen protection alone, not what the plate feeds the organism.
A demanding model organism
The challenge organism is Porphyromonas levii, a strict anaerobe standardized to a 2.0 McFarland suspension, plated on four replicates per condition.
A consistent gradient
The same ordering appears in the mean counts, the survival percentages, and the plate images. Recovery rose in step with protection at every timepoint.
Download the full white paper
Get the complete study, including all data tables, figures, plate images, and methods. Delivered to your inbox as a PDF.
- Full absolute and survival data for all five media
- Plate images and the automated-streaking analysis
- Practical checklist you can apply this week
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About OxyPRAS Plus
OxyPRAS Plus Brucella agar (P-BRU-BA) combines a traditional pre-reduced anaerobically sterilized base with the Oxyrase enzyme system, an active oxygen scavenger built into the medium. Where passive media start reduced and then oxidize during handling, OxyPRAS Plus keeps consuming oxygen at the agar surface throughout benchtop exposure.
In this study it preserved the most recovery of any medium tested, at every interval measured.
- Active protection, not just a reduced start. The enzyme system counters oxygen that arrives during handling.
- Built on a proven PRAS base. Familiar Brucella agar performance for anaerobic recovery.
- Built for real workflows. Designed to hold up to manual and automated handling alike.
See it on your own bench
The most convincing evidence is your own. Request a free sample and evaluate OxyPRAS Plus against your current media, under your real handling conditions.
Questions labs ask
Who is this white paper for?
Laboratory directors and managers, clinical and veterinary microbiologists, medical technologists, and anyone choosing media for anaerobic culture. It is written to be useful whether you handle plates manually or on an automated streaker.
What was actually measured?
Recovery of the strict anaerobe Porphyromonas levii on five Brucella agar preparations after the agar was left exposed to open benchtop air for 0, 30, 60, 120, and 180 minutes before inoculation, with four replicate plates per condition. Recovery is reported as both absolute colony counts and survival versus each medium’s own baseline.
Is OxyPRAS Plus a new base medium?
No. It uses a standard Brucella agar nutrient base, so it fits existing anaerobic workflows. The difference is the Oxyrase enzyme system that actively scavenges oxygen at the agar surface.
Can I evaluate it myself?
Yes. Check the sample box on the form, or use the request-a-sample button, and our team will arrange an evaluation in your own lab.