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Description
Lactococcus lactis subsp. lactis is a gram-positive, mesophilic homofermentative bacterium that is obtained from sour milk. It possesses non-sporulating and non-motile short chains with a typical length of 0.5 to 1.5 μm usually arranged in pairs. It has been deposited under American Type Culture Collection (ATCC) accession number 19435. The ingredient is manufactured under aerobic fermentation conditions before heat inactivation. The mixture is then spray-dried to yield a powder containing not less than 2.8 billion non-viable cells/mg of pasteurised Lactococcus lactis subsp. lactis.
| Test | Method reference | Acceptance criteria |
|---|---|---|
| CHARACTERISATION | ||
| General properties | ||
| Appearance | Visual examination | Ivory coloured homogeneous powder |
| Morphology | Microscopic examination[1] | Cocci shaped with a typical length of 0.5 to 1.5 μm. |
| Loss on Drying | USP <731> | ≤7.0% (w/w) |
| Particle size | USP <786> | ≥95% through a 500 µm sieve |
| Identification | ||
| Gram staining | USP <1113> | Gram-positive |
| PCR | VNTR PCR method[2] | Matches Lactococcus lactis subsp. lactis strain ATCC 19435 |
| Assay | ||
| Total non-viable cell count | Particle counter method[3] | ≥2.8 × 10⁹ cells/mg |
| Total viable cell count | Plate count method [4] | <10 CFU/g |
| Elemental impurities | ||
| Lead | Ph. Eur. 2.4.20 | ≤0.4 ppm |
| Arsenic | Ph. Eur. 2.4.20 | ≤0.2 ppm |
| Mercury | Ph. Eur. 2.4.20 | ≤0.1 ppm |
| Cadmium | Ph. Eur. 2.4.20 | ≤0.5 ppm |
| Microbiology | ||
| Total aerobic microbial count | USP <61> | ≤3,000 CFU/g |
| Total combined yeasts and moulds count | USP <61> | <100 CFU/g |
Footnotes
- Disperse the product in PBS and examine the morphology at 1000× magnification using a phase-contrast microscope.
- PCR-based identity test targeting strain-specific tandem repeat regions using proprietary primer sets. Identification is confirmed by comparing banding pattern to the reference strain (ATCC 19435/NITE (NBRC) 100933).
- The sample is weighed and suspended with PBS. The sample solution is sonicated, and the particle count is measured with a particle count analyser using electrical detection zone method.
- The viable count of Lactococcus lactis subsp. lactis is determined on agar plates by platting the suspended heat-killed substance. The plates are incubated for 3-5 days at 30°C in an aerobic chamber. The cell count is conducted manually under a light microscope.
Abbreviations
CFU = Colony forming units
PCR= Polymerase chain reaction
Ph. Eur. = European Pharmacopoeia
PBS = Phosphate buffered Saline
ppm = Parts per million
USP = United States Pharmacopeia
VNTR = Variable Number of Tandem Repeats