RNA isolation from actinomyces

I am trying to isolate RNA from a high GC, gram positive, marine actinomyces and I am consistently getting low yields. I have tried several kits. I feel my problem lies in the cell disruption step. I am using the Ribopure Bacteria Kit from Ambion now and I have extended the bead beating step out to 30 min. I have also tried grinding the cells under liquid nitrogen in a 1.5 ml tube. My yields have improved with the bead beating extended but they are still sub-par for my needs. Any suggestions?