Testing Methods For Bacillus subtilis Detection
B. subtilis
Bacillus subtilis is a common microorganism that is often used in the feed industry, namely its production and and also as an additive after production. Its detection is crucial for ensuring the quality and safety of feed. The following will provide a detailed introduction to the various detection methods, conditions, and standards of testing for Bacillus subtilis in feed. Each method has its own advantages and drawbacks, therefore the user must take into account the specific situation and scenario of application.
Traditional Cultivation Method
Sample processing: Weigh a certain amount of sample, add diluent for mixing and ultrasonic treatment to ensure the release and dispersion of Bacillus subtilis.
Dilution: Gradient dilute the processed sample to ensure that each dilution of the sample can be evenly coated on the culture medium.
Inoculation: Apply the diluted sample onto a nutrient agar plate, label the analysis number, date, and dilution level.
Cultivation: Place the inoculated plates in a 37 ℃ constant temperature incubator for 16-20 hours and observe the growth of bacterial colonies.
Observation of colony characteristics: The colonies of Bacillus subtilis usually exhibit rough and irregular shapes on solid culture media, with larger milky white to grayish white colonies.
Biochemical identification: Through a series of biochemical tests such as oxidase test, catalytic enzyme test, gelatin liquefaction test, and nitrate reduction test, further confirm whether the isolated bacteria are Bacillus subtilis.
Molecular Biology Method
PCR detection: The presence of Bacillus subtilis is detected by amplifying its specific gene sequence through polymerase chain reaction (PCR). This method has high sensitivity and strong specificity, but requires expensive equipment and professional knowledge.
Fluorescence quantitative PCR (qPCR): Quantitatively detecting the presence of Bacillus subtilis by amplifying specific gene sequences, with high sensitivity and specificity, but also requiring professional equipment and operational knowledge.
Immunological Methods
Enzyme linked immunosorbent assay (ELISA): It indirectly reflects the content of Bacillus subtilis specific antibodies in a sample by detecting their binding reaction with antigens. This method has high sensitivity, but may be affected by the quality of reagents and experimental procedures.
Immuno-magnetic Bead Method: Using immune-magnetic beads to specifically capture Bacillus subtilis and then perform detection. This method also has high sensitivity and specificity, but the operation is more complex.
