The use of cellulose products to reduce agar concentration in microbiological media

The use of agar in media for culturing microorganisms is fundamental to microbiological investigations. Shortages of agar have caused increased costs and difficulty in obtaining media. Evidence is presented for the use of carboxymethylcellulose (CMC), an inert compound, in conjunction with agar to reduce the concentration of agar necessary to achieve a solid plating surface. A variety of bacteria, blue-green bacteria, fungi, and a yeast were tested for growth on CMC agar media. T-2 bacteriophage and three cyanophages were tested for plaque-forming efficiency on CMC agar plates. Selective and differential media were also formulated with a CMC agar supplement. Growth of all microorganisms was comparable on CMC and agar control. Use of cellulose products provides a means of decreasing agar consumption without affecting successful cultivation of microorganisms.