explain about best transferring a soil sample to lab, with below goals:
bacterial plate count
total E.coli count
Soil samples are collected normally at a depth of 6 inches (15cm) and transferred to clean containers. Three to five samples at-least are taken for each replicate and mixed evenly. From the mixed sample at least 10-25 g of soil are taken as representative sample of the particular replicate. The soil dilution and plate count method has been most widely used for enumeration and isolation of soil bacteria. The other method can be used are: The soil plate method, Enrichment cultures method, The buried slide method, Immersion plate and tube method and Direct microscopic examination of soil. The different media can be used for isolating bacteria from soils are; Nutrient agar, Soil-extract agar, Asparagine-mannitol agar, Plate count agar, Reinforced clostridial medium, Yeast extract mannitol agar etc depends on the bacteria you want to isolate. For E. Coli you may use Chrome agar media as stated.
Soil samples are collected normally at a depth of 6 inches (15cm) and transferred to clean containers. Three to five samples at-least are taken for each replicate and mixed evenly. From the mixed sample at least 10-25 g of soil are taken as representative sample of the particular replicate. The soil dilution and plate count method has been most widely used for enumeration and isolation of soil bacteria. The other method can be used are: The soil plate method, Enrichment cultures method, The buried slide method, Immersion plate and tube method and Direct microscopic examination of soil. The different media can be used for isolating bacteria from soils are; Nutrient agar, Soil-extract agar, Asparagine-mannitol agar, Plate count agar, Reinforced clostridial medium, Yeast extract mannitol agar etc depends on the bacteria you want to isolate. For E. Coli you may use Chrome agar media as stated.
Soil samples if not immediately in use can be stored at 4 degree in sterilized container at low temperature to avoid bacterial and fungal contamination.
Thank you. How much time we can store it that has minimun effect on bacterial total count? Plz give reference ....
There are some references, hoiw the conditions of storage influence microbial community structure:
http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0070460&type=printable
http://www.eajournals.org/wp-content/uploads/Effect-of-Length-of-Soil-Sample-Storage-on-Soil-Microbiological-and-Bochemical-Properties-in-Uyo-Nigeria.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148093/pdf/nihms-211815.pdf
http://ac.els-cdn.com/S0038071712001459/1-s2.0-S0038071712001459-main.pdf?_tid=f16a9dcc-80d4-11e7-a4a1-00000aab0f01&acdnat=1502703953_b24b01c368441396eda31af706d5e03f
According to my personal experience it is the best to store soil samples for microbiological analyses at 4 degrees centigrade fpor 24 hours at maximum.
Best regards Vit
Directly after sampling put it in a sterilized container under toluene
Collect sample by sterilized sampler, put it in a sterile vial and preserved at 4 degrees centigrade aseptically for transferring to lab. Commonly ice bag (4 degrees centigrade) is used for short distance to bring it from field to lab and it can be employed for platting.
Collect soil at a depth as per your design e.g. 0-10, 10-20 etc into a polybag using sampler and make it air tight. Keep it at 4 degree C. Use sterilized sampler and polybag.
collect soil samples - surface, sub-surface, depth (10-15 cm) and mix them well. weigh 1 g soil and suspend it in 10 ml of sterile distilled water/ buffered saline (Master dilution). Perform serial dilution and inoculate on sterile agar medium. (0.1 mL - spread plate; 1 mL- pour plate). In order to isolate colonies, spread plate is preferable.
Apart from Chrome agar, these media can also be used to enumerate E. coli
E.coli on
EMB Agar - metallic sheen green-coloured colonies
MacConkey Agar - pale pink colonies
these are selective media for E.coli.
It is advisible to do the experiment quickly once it reaches the lab. Upon storage, your chances or probability to enumerate required bacteria dimishes.
@ Paul, Single colony method, I suppose, is the best for soil bacteria sampling.
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