Phytopathology Volume N . 7 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...or no advantage; in many cases it somewhat retards the growth of wood-destroying fungi. frequently been used in synthetic media as a source of nitrogen, while various carbohydrates have been used as a source of carbon. The first step in this work was to select a nutrient solution of inorganic salts with di-ammonium phosphate as the source of nitrogen. This solution was used as the basis for testing the nutrient value of various carbohydrates and consisted of the following: Di-potassium phosphate (kjhpoj) 4 grams Di-ammonium phosphate ( (NH4)2HP04) 2 grams Magnesium sulphate (MgS04.7H20) 2 grams Agar-agar (powdered) 15 grams Distilled water 1000 cc. Varying concentrations of the following carbohydrates, usually 20 or 40 grams in a liter of the nutrient solution, were used: Lactose, maltose, cane-sugar, galactose, glucose and glucosamin. Growth of the fungus was compared with that on malt extract agar as a standard. The organism grew fairly well in every case. Cane-sugar and glucose, however, gave the most favorable indications, the growth on the canesugar being slightly more favorable. Since, however, the growth might be changed by using other nitrogen sources in addition to di-ammonium phosphate, it was decided to continue the use of both sugars in further work. The next step was to obtain a nitrogen source more available to the fungus than di-ammonium phosphate, so the following substances were tested by adding 2 and 4 grams, respectively, to a liter of the nutrient solution containing forty grams of cane-sugar: Asparagin, sodium asparaginate, ammonium asparaginate, caffein, guanidin carbonate, glycin, leucin, creatinin and betain. With 0.2 and 0.4 per cent of caffein and guanidin carbonate, respectively, no growth of the fungus occurred, but in all the ot...