PLATE COUNTS OF BACTERIA AND FUNGI IN A SALINE SOIL

Numbers of bacteria and of fungi in a saline soil were about one-fifth of numbers in a Red River clay soil. Bacterial counts on two soil-extract agar media, one prepared from the saline soil and the other from Red River soil, were the same, and the populations on the two were the same as shown by the replica plating technique. They were larger than counts on sodium albuminate agar or on asparagin–mannitol agar. Likewise, fungal counts on either soil-extract agar, with 0.02% dipotassmm phosphate, 0.1% glucose, and 0.1% peptone, were higher than counts on Waksman's acidified medium, or on Martin's medium, or on Smith and Dawson's medium. Interestingly, fungal counts on a medium with the same three chemicals as the soil-extract media but with the soil extract replaced by water were as high as those on the soil-extract media. Different levels of potassium phosphate were tested in each of the above media. In each medium for bacteria, and in each for fungi, counts varied inversely as the amount of potassium phosphate. The same held true when sodium phosphate was used instead of potassium phosphate in each medium.