Lactose broth (1076610500) chủ yếu được sử dụng như một môi trường tăng sinh để phát hiện Escherichia coli trong mỹ phẩm. Nó cũng có thể được sử dụng để nuôi cấy các vi khuẩn Gram âm. Sử dụng ống Durham để phát hiện sự lên men của lactose. Lactose Broth được sử dụng làm môi trường nuôi cấy khuẩn Salmonella và phát hiện vi khuẩn coliform từ thực phẩm, sữa, nước và các mẫu dược phẩm.
Sure! Here is an overview and detailed description of Lactose Broth, focusing on Merck’s product with the catalog number 107661:
Lactose Broth (Merck) | 107661: An Overview
Lactose Broth is a microbiological culture medium used primarily for the cultivation of coliform bacteria. These bacteria are often used as indicators of sanitary quality of water and foods. Merck, a renowned global provider of high-quality lab and research materials, produces and supplies a Lactose Broth under the catalog number 107661, trusted by many laboratories worldwide.
Composition and Properties
Lactose Broth is formulated with essential ingredients that provide a suitable environment for the growth of coliform organisms. The key components of this medium include:
- Peptone: This serves as a source of nitrogen and other essential growth factors for the microorganisms.
- Lactose: As a carbohydrate source, lactose supports the growth of lactose-fermenting coliform bacteria.
- Sodium chloride (NaCl): This maintains the osmotic balance in the medium.
The typical composition per liter of distilled water is:
- Peptone: 5.0 g
- Lactose: 5.0 g
- Sodium chloride: 5.0 g
Preparation and Storage
Preparation of Lactose Broth is straightforward. Dissolve the required amount of the dehydrated medium in distilled water. The typical concentration is 13 grams per liter. Heat to boiling to ensure complete dissolution of the medium. Once dissolved, distribute into final containers or test tubes and sterilize by autoclaving at 121°C for 15 minutes. After sterilization, store the prepared medium at 2-8°C, protected from light, until use.
Usage and Application
Lactose Broth is primarily used for the detection and enumeration of coliform bacteria, which serve as indicators of fecal contamination. Its applications include:
- Water Testing: Used in the presumptive test for coliforms in water. Samples are inoculated into Lactose Broth and incubated. The production of gas within 24-48 hours is a positive indication of coliform presence.
- Food and Dairy Industry: Employed in testing dairy products, processed foods, and raw food materials for microbial contamination.
- Pharmaceutical Testing: Used in quality control labs to test for microbial contamination in various pharmaceutical products.
Advantages and Limitations
Advantages:
- Efficiency: Supports rapid growth and detection of coliform bacteria.
- Versatility: Suitable for various types of samples, including water, foods, and pharmaceuticals.
- Reliability: A well-established method with a high degree of reproducibility.
Limitations:
- Selectivity: While efficient, it is not highly selective for coliforms and may support the growth of other lactose-fermenting bacteria.
- Sensitivity: The medium requires proper incubation conditions for accurate results, and false positives/negatives can occur without meticulous technique.
Regulatory and Safety Information
Merck’s Lactose Broth (107661) complies with various international standards for microbiological culture media, including those set by ISO (International Organization for Standardization) and the United States Pharmacopeia (USP). It is essential to follow proper laboratory practices and safety guidelines while handling and preparing the medium.
Conclusion
Lactose Broth is an indispensable tool in microbiological testing and research. Its simplicity, reliability, and efficiency make it a staple in laboratories focused on water quality, food safety, and pharmaceutical quality control. Merck’s Lactose Broth (107661) remains a preferred choice due to its consistent quality and compliance with international standards.
I hope this overview provides you with a comprehensive understanding of Lactose Broth by Merck. If you have any specific questions or need further details, feel free to ask.
Chemical Properties
Lactose Broth supports the growth of a variety of organisms, making it a non-selective medium. Here are some chemical properties and behavior of the medium:
- pH: The pH of the medium is typically around 6.9 ± 0.2 at 25°C. This pH range is optimal for the growth of coliform bacteria.
- Appearance: The dehydrated medium appears as a homogeneous, free-flowing powder, generally light beige in color.
- Preparation Clarity: Once prepared, the medium should be clear to slightly opalescent, with a light amber hue.
Mechanism of Action
The primary function of Lactose Broth is to detect lactose-fermenting bacteria, especially coliforms. Here’s a simplified mechanism:
- Fermentation: Coliform bacteria utilize lactose as a carbon source. During this fermentation process, acid and gas are produced.
- Gas Production: The presence of gas bubbles in the Durham tube (small inverted tube) within the broth indicates positive lactose fermentation.
- Acid Production: Acid production can be detected using pH indicators, but in lactose broth, the key signal is the gas production.
Quality Control
Merck ensures stringent quality control measures for Lactose Broth (107661). The medium is tested for:
- Sterility: The medium is sterilized and checked to ensure it’s free from contaminants.
- Growth Promotion: The medium is tested with known coliform strains like Escherichia coli to ensure it promotes adequate growth and gas production.
- Performance: The ability of the medium to support the growth of target microorganisms and the production of gas is consistently monitored.
Storage and Shelf Life
Proper storage conditions are essential to maintain the efficacy of Lactose Broth:
- Storage Conditions: Store the dehydrated medium in a tightly sealed container at 10-30°C, away from light. For the prepared medium, refrigeration at 2-8°C is recommended.
- Shelf Life: The shelf life of the dehydrated medium is typically 3 years from the date of manufacture, provided it’s stored under recommended conditions.
Practical Tips for Using Lactose Broth
When using Lactose Broth in the laboratory, consider these practical tips:
- Inoculation: Use sterile techniques to prevent contamination. Inoculate the medium with the sample as quickly as possible.
- Incubation: Incubate inoculated tubes at 35-37°C. Ensure the tubes are kept upright to accurately observe gas production.
- Observation: Check for gas production at intervals (typically 24 and 48 hours). A positive result is indicated by the presence of gas in the Durham tube.
Environmental Impact
Lactose Broth, like other microbiological media, should be disposed of according to local regulations. Autoclave any used media before disposal to eliminate any live cultures.
Troubleshooting
Common issues and solutions when using Lactose Broth:
- No Gas Production: If no gas is produced, ensure the inoculum was sufficient and the sample wasn’t too diluted. Check incubation temperature and time.
- Turbidity Without Gas: If the broth turns turbid but no gas is produced, it may indicate non-coliform bacteria growth. Further tests might be necessary to identify the microorganisms.
By covering these additional details, I hope this provides an even deeper understanding of Lactose Broth (Merck) | 107661. Let me know if there’s any more specific aspect you’d like to explore!
