English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In the course of some studies on the kinetics of growth and the biochemical activities of a marine diatom it became desirable to obtain bacteria-free cultures. The classicalmethod of obtaining such pure algal cultures involves either repeatedly washing single cells in sterile medium or obtaining discrete bacteria-free algalcoloniesby growth on a solidmedium. Both these methods have been widely applied to fresh-water species by Pringsheim (1946) and others, whilst Chu (1946) has used both methods with the marine diatom Nitzschia closterium(Ehrenberg) Wm. Smith forma minutissima. The bacteria associated with algae (especiallydiatoms) are normally very tenaciously attached, and some (e.g. the blue-green algae)may penetrate the gelatinous sheaths. This characteristic of the bacteria may make a washing procedure impractical. Chu found it necessary to make a minimum of six initial subcultures in sterile medium under conditions that favoured algal rather than bacterial growth (low organic content of medium, high light intensity and low temperature) before selecting single cells for washing in sterile medium, It seems probable, therefore, that the washing technique will remove free-living but not attached bacteria (cf. the results of Zobell &Allen (1935), who showed that more than half the bacteria in the sea will attach themselves to solid surfaces so tenaciouslyas to resist being washed off with running water). The plating technique does not seem to be widelyapplicable to marine species. Some thirty species have been tried during the present studies including representatives of the groups Cryptophyceae, Chrysophyceae, Chlorophyceae, Dinophyceae and Bacillariophyceae. Only two of the Chlorophyceae(Chlorellasp. and Chlamydomonasp.) and one Bacillariophyceae (Nitzschia closteriumf. minutissima)grew on Erdschreiber medium solidified with 1'5 %agar. Numero"psworkershave investigatedchemicaland physical treatments in the hope of finding one that is bactericidaland which is tolerated by algae. Zobell has attempted to use heat, ultraviolet irradiation and various chemicalbactericidal compounds (Zobell & Long, 1938). Of the latter acriflavine proved to be bacteriostatic in concentrations that did not

On the use of antibiotics for isolating bacteria-free cultures of marine phytoplankton organisms