Substrate costs yields, optimizing

In short, microbial cells can be employed as very effective reactors for the conversion of substrates to products, operating in mixed aqueous-apolar systems, optimized for the best space-time yields attainable at lowest cost. 

Shortly after, the same group published a study where readily available carboxylic acids, diacids, and N-protected amino acids were screened as proton sources [6]. The same substrates were used in the presence of citric acid instead of HF. This catalytic system displayed somewhat lower selectivity. For example, by using similar experimental conditions in the presence of citric acid at —10 °C, the enantioseiective protonation of silyl enol ether 5c afforded the corresponding ketone 7c in excellent yield but lower enantioselectivity (up to 75% ee, Scheme 7.4, to be compared with entry 3, Table 7.1). However, upon further optimization, this process seems appealing in terms of simplicity, practicability, environmental concerns, and cost therefore, adjustable for industrial use. 

In the field of chemical analysis, biosensors have undergone rapid development over the last few years. This is due to the combination of new bioreceptors with the ever-growing number of transducers [1]. The characteristics of these biosensors have been improved, and their increased reliability has yielded new applications. Recently, a new technique of enzyme immobilization has been developed to obtain biosensors for the determination of enzyme substrates [2]. It is based on the enzyme adsorption followed by a crosslinking procedure. Therefore, a penicillin biosensor can be obtained and associated with a flow injection analysis (FIA) system for the on-line monitoring of penicillin during its production by fermentation [3-4]. This real-time monitoring of bioprocess would lead to optimization of the procedure, the yield of which could then be increased and the material cost decreased. 

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