Thus, although our data do not show any significant advantage in PHA yield by elimination of the depolymerase, there is likely some value in achieving its elimination. A method of eliminating PhaZ activity is needed that retains transcription rates of both phaC1 and phaC2. However, since elimination of PHA depolymerase activity had little effect on PHA productivity, its elimination is not required for commercial production by carbonlimited fed-batch culture of P putida KT2440.