Thomas, P. and Sekhar, A.C. and Mujawar, M.M. (2012) Nonrecovery of varying proportions of viable bacteria during spread plating governed by the extent of spreader usage and proposal for an alternate spotting-spreading approach to maximize the CFU. Journal of Applied Microbiology, 113 (2). pp. 339-350.
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Abstract
AIMS: To elucidate the cause of high variations and inconsistencies in bacterial CFU observed within and between different experiments while assessing viable bacterial counts through spread plating (SP). METHODS AND RESULTS: Following the inconsistent results, CFU estimations were undertaken through conventional SP using the spreader, or a modified approach that did not use spreader employing four organisms. The latter approach involving spotting-and-tilt-spreading of inoculum on agar surface [spotting spreading (SS)] yielded higher CFU by 11-120% over the weighted average depending on the organism and diluent. The adverse effect owing to the spreader was the most obvious in Escherichia coli followed by Staphylococcus epidermidis, Enterobacter cloacae and Bacillus pumilus. Plate attributes that determined the surface moisture levels of agar medium and the spreading practice adopted by the personnel formed two other major influencing factors. Plating for shorter periods (<60 s) using fresh 15/20 ml plates caused loss of 3-12% CFU owing to inoculum adhesion to spreader irrespective of glass or polypropylene make. On the other hand, prolonging the plating brought down the CFU significantly. Spreader movement on agar surface subsequent to the exhaustion of free moisture, which was marked by the experiencing of some friction to smooth spreader movement, was detrimental to vegetative cells, while Bacillus spores were less affected...
| Item Type: | Article |
|---|---|
| Author Affiliation: | Division of Biotechnology, Indian Institute of Horticultural Research, Hessarghatta Lake, Bangalore, India. |
| Subjects: | Soil Science and Microbiology > Microbiology |
| Divisions: | General |
| Depositing User: | Ms K Syamalamba |
| Date Deposited: | 06 Oct 2014 05:54 |
| Last Modified: | 06 Oct 2014 05:54 |
| Official URL: | http://dx.doi.org/10.1111/j.1365-2672.2012.05327.x... |
| URI: | http://eprints.icrisat.ac.in/id/eprint/13478 |
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