Chitin utilization in boiled medium without BSA. BSK-II without GlcNAc and BSA was supplemented with 7% rabbit serum. Wild-type cells were cultured in unboiled medium (A) or medium that was boiled for 10 min (B). Late-log phase cells were diluted to 1.0 × 105 cells ml-1 and the following substrates were added: 1.5 mM GlcNAc (closed circle), No addition (open circle), 75 μM chitobiose (closed triangle), 50 μM chitotriose (open triangle) or 25 μM chitohexose (closed square). Cells were enumerated daily by darkfield microscopy. This is a representative experiment that was repeated three times.