| 摘要 |
<p>Prodn. of biological nutrients substrates comprises combining predetermined amts. of (a) liq. nutrient; (b) pectin material (I) of low (pref. about 5%) methoxy content and (c) a growth-permitting gel which contains among other things polyvalent metal cations which gel (I). Pref. (a) and (b) are mixed first to provide 10-50g (I) per 1, and the total vol. of this mixt. is 3-20 times that of (c). Esp. a mixt. of (a) and (b) is added to a culture vessel (Petri dish) which contains a first layer of (c). The medium is pref. buffered with Na2HPO4, NaH2PO4, Na3PO4, NaHCO3, or Na2CO3 and the metal for gelling (I) is esp. Ca2+ used at 100-125 mg per g (I). The substrates can be packaged and sterilised ready for use so are esp. suitable for teaching laboratories etc. which have limited resources for making their own media. The mixts. can be used hot, warm or cooled (contrast agar) and are suitable for prokaryotic and eukaryotic organisms, cells and tissues. Pectin is cheaper than agar and only a few microorganisms are capable of hydrolysing gelled pectin.</p> |
