Raven Biotech’s stand-alone Methanol Sensor provides reliable, on-line control of methanol concentration in cultures of Pichia pastoris or other methlotrophic organisms, allowing fast and efficient optimization of recombinant protein production. Accurate regulation of the methanol concentration is necessary to maintain induction and prevent the accumulation of methanol to cytotoxic levels. In the past, the dissolved oxygen spike method has been used to estimate the methanol concentration. This technique, however, exposes the cells to potentially non-inducing levels of methanol and cannot be easily implement with Mut- clones or with mixed substrate feeds. Raven’s Methanol Sensor overcomes these limitations, giving accurate monitoring and control of methanol concentration in cultures of Mut+, Mut- and MutS recombinant Pichia pastoris clones.