HiMedia Laboratories GmbH, Marie-Curie-Str. 3, 64683, Einhausen, Germany.
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HiCrome™ Nickels & Leesment HiVeg™ Agar Base
For the enumeration of citrate-fermenting lactic acid bacteria from milk, milk products and mesophilic starter cultures.
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Intended Use
Recommended for the enumeration of citrate-fermenting lactic acid bacteria from milk, milk products and mesophilic starter cultures.
Composition**
| Ingredients | g/L |
|---|---|
| HiVeg® hydrolysate | 18.000 |
| Yeast extract | 4.500 |
| Gelatin | 2.250 |
| Glucose (Dextrose) | 4.500 |
| Lactose | 4.500 |
| Sodium chloride | 3.600 |
| Trisodium citrate dihydrate | 1.800 |
| Calcium lactate pentahydrate | 8.000 |
| Tricalcium dicitrate tetrahydrate | 6.650 |
| Carboxymethyl cellulose (CMC) | 0.400 |
| Chromogenic substrate (X-gal) | 0.200 |
| Agar | 15.000 |
| Final pH (at 25°C) | 6.65±0.05 |
**Formula adjusted, standardized to suit performance parameters
Directions
Suspend 66.0 grams (the equivalent weght of dehydrated medium per litre) in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C. If desired, add rehydrated contents of 2 vials of Van100 Selective supplement (FD245). Mix well and pour into sterile Petri plates.
Principle And Interpretation
Lactic acid bacteria are widespread in nature and are best known for their activities in major food such as dairy, meat and vegetable products (1). Testing for lactic acid bacteria in dairy products may be useful for various reasons like evaluating lactic starter cultures; determining the cause of acid defects in milk products, controlling the quality of cured cheese, cultured milks and uncultured products containing added cultures (2). HiCrome® Nickels and Leesment Medium is a modification of Modified Nickels and Leesment Medium formulated as per APHA (1) and is used for the enumeration of citrate-fermenting lactic acid bacteria using colony count technique at 25°C. HiCrome® Nickels and Leesment HiVeg® Agar Base is same as HiCrome® Nickels and Leesment Medium except that the animal based peptones are completely replaced with vegetable peptones to avoid the BSE/TSE risks associated with animal peptones. HiVeg® hydrolysate and yeast extract serve as carbon and nitrogen sources, long chain amino acids, vitamins and other essential growth nutrients. Lactose and glucose are the carbohydrate source in the medium. X-gal differentiates between Lactococcus lactis subsp. lactis and Leuconostoc species. Lactococcus lactis subsp. lactis biovar diacetylactis colonies are white with a clear zone. Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris colonies are white without a clear zone. Leuconostoc species are blue, with or without a clear zone. HiCrome® Nickels and Leesment HiVeg® Agar Base with the addition of HiCrome® Nickels and Leesment Supplement (FD245) can be used for enumeration of Leuconostoc (1). Vancomycin acts as a supplement for the selective isolation of Leuconostoc from a mix flora of lactic acid bacteria. Sodium chloride maintains osmotic equilibrium and various salts provides essential ions.
Type of specimen
Food and dairy samples.
Specimen Collection and Handling
For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (3,4,5). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines shall be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations
- Due to variable nutritional requirements, some strains show poor growth on this medium.
- Slight colour variation may be observed depending upon the utilization of the substrate by the organism.
Performance and Evaluation
Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.
Quality Control
Appearance
Cream to light yellow homogeneous free flowing powder
Gelling
Firm, comparable with 1.5% Agar gel
Colour and Clarity of prepared medium
White coloured, opaque gel containing white precipitate forms in Petri plates.
Reaction
Reaction of 6.6% w/v aqueous solution at 25°C. pH : 6.65±0.05
pH
6.60-6.70
Cultural Response
Cultural characteristics observed after an incubation at 25-30°C for 48-72 hours.
| Organism | Growth | Growth with FD245 | Colour of colony |
|---|---|---|---|
| L. lactis biovar diacetylactis | good-luxuriant | inhibited | white with a clear zone |
| L. lactis subsp lactis ATCC 19435 (00016*) | good-luxuriant | inhibited | white without a clear zone |
| L. lactis subsp cremoris ATCC 19257 | good-luxuriant | inhibited | white without a clear zone |
| Leuconostoc mesenteroides ATCC 9135 (00108*) | good-luxuriant | good-luxuriant | blue without clear zone |
Key: (*) Corresponding WDCM numbers.
Storage and Shelf Life
Store between 15-25°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (1,6).
| Product Name | HiCrome™ Nickels & Leesment HiVeg™ Agar Base |
|---|---|
| SKU | MV1712 |
| Product Type | HiVeg™, HiCrome™ |
| Physical Form | Powder |
| Origin | Animal Free (Veg) |
| Packaging type | HDPE |
| References | 1.American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., Washington D.C. 2.Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition. |
| Customized Product Available | No |
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