Published online by Cambridge University Press: 15 May 2009
The prevalence of the different types of coli–aerogenes bacteria has been determined in various soils collected from widely separated locations in the United Kingdom and in Denmark. Of the soils examined, 27% contained no coli–aerogenes organisms in 15 g. of soil tested. The number of these organisms in the positive soils was very low; only 11% had confirmed counts greater than 100 organisms/g. and 33% less than 1 organism/g.
The most prevalent organism isolated was Bacterium coli type I, whatever the location or vegetation type of the soil; intermediate type I, Bact. aerogenes type I and Bact. coli type II were the only other organisms of numerical importance. The annual application of large amounts of either farmyard or inorganic manures produces no permanently large population of coli-aerogenes organisms in soils.
Presumptive tests in MacConkey broth were unreliable, since only 6 % of the positive tubes from hill and moorland soils and 28 % from arable soils were confirmed as containing coli-aerogenes bacteria. Such discrepancies are considered to be partly due to coliform bacteria with weak lactose-fermenting properties.
It is considered that there is now sufficient experimental evidence to discredit statements that soil is the natural habitat of Bact. aerogenes or intermediate types of coli-aerogenes organism.
To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about saving content to Dropbox.
To save this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about saving content to Google Drive.