Lab M reacts to changing industry preferred testing methods

11-Aug-2016 - Last updated on 12-Aug-2016 at 11:07 GMT

Lab M has said it is important to listen and respond to industry changes as it launched its MMGA pre-poured plate.

The Pinnacle MMGA (ISO), Mineral Modified Glutamate Agar, pre-poured media plate is formulation compliant to ISO 16649-1 and performance compliant to ISO 11133 for recovery of stressed and injured β-glucuronidase-positive E. coli in food, water and feed samples.

MMGA is the resuscitation medium specified by ISO 16649-1 and is an additional step prior to enumeration on Tryptone Bile Glucuronide Agar (TBGA, TBX).

Users place a filter membrane onto the plate, add the sample and incubate for four hours, then transfer the membrane straight to the TBGA (TBX) plate for incubation and enumeration.

Stressed microorganisms

Melanie Patterson, Lab M’s market development manager, said all microorganisms can be subjected to a degree of stress due to the nature of the food manufacturing process.

“Heating, chilling or drying products, as well as the addition of preservatives, could stress or injure organisms such as E. coli. This means that the microorganisms are still viable but difficult to grow,” she said.

“The term used for these types of organisms is viable but non-culturable (VBNC) or not immediately culturable.

“We were informed by our customers that the use of MMGA in accordance with ISO 16649-1 was the new preferred testing method. This change is what prompted Lab M to develop our ISO compliant MMGA pre-poured plate.”

MMGA contains amino acids, vitamins and salts formulated to promote recovery of stressed or damaged organisms.

ISO reference method

ISO 16649-1 is the reference method for enumeration of stressed or injured E. coli, said Patterson.

“It is this method which specifies that MMGA should be used for a four hour period as a recovery step prior to incubation on TBX. Alternative methods are available but not within ISO,” she said.

“If the E. coli are not given the opportunity to recover they will not grow on TBX. This will give a greatly reduced colony count with little value.”

Lab M’s Pinnacle range of prepared media is QC tested under its ISO 17025 accreditation scope and is manufactured using its dehydrated culture media (DCM).

The firm also offers its MMGA and TBGA (TBX) media in a DCM format.

Patterson said pre-poured media plates are supplied ready to use so there is no need to weigh, autoclave or pour any media saving time, resource and labour in the lab.

“Lab M’s full range of Pinnacle pre-poured plates is also QC tested under our ISO 17025 UKAS accreditation scope which guarantees the quality of our product and by complying with ISO 11133 it also means that there is minimal internal QC required by the customer.

“Using pre-poured plates can also help to support labs of all sizes, especially when sample numbers can vary.”