A Pichia anomala Strain (P. anomala M1) Isolated from Traditional Greek Sausage is an Effective Producer of Extracellular Lipolytic Enzyme in Submerged Fermentation

Ayeast isolate, selected for its lipolytic activity from a meat product, was characterized as Pichia anomala. Lipolytic activity, determined on p-NPA as esterase, was maximum at 28 °C, pH 6.5, and induced by the short chain triglyceride tributyrin. Fermentations in 2 L and 10 L stirred tank bioreactors, with 20 and 60 g/L glucose respectively, showed that in the second case lipolytic activity increased 1.74-fold, while the biomass increased 1.57-fold. Under otherwise identical aeration conditions, improved mixing in the 10 L reactor maintained higher dissolved oxygen levels which, along with the elevated glucose concentration, resulted in significant increase of specific rates of lipolytic activity (51 vs. 7 U/g/L), while specific rates of growth and glucose consumption maintained lower. The Crabtree-negative yeast (glucose insensitive growth) exhibited a Pasteur effect at lower dissolved oxygen concentrations while elevated glucose prevented ethanol formation under oxygen saturation. The particular physiological traits can be exploited to obtain significant lipolytic activity in a scalable aerobic process

Aspects on the catalysis of lipase from porcine pancreas (type VI-s) in aqueous media: development of ion-pairs

This article reports a first contribution for the elucidation of catalytic mechanism of Lipase from porcine pancreas, type VI-s (PPL), in hydrolyzing an ester substrate in aqueous media. The conclusions were based on the pH-profiles of Michaelis-Menten parameters k cat/Km, k cat and Km, as well as on the absolute temperature profile of k cat/Km, obtained during the hydrolysis of p-nitrophenyl laurate by PPL. It was found that (a) PPL performs catalysis by means of ion pairs formed either as Ser152-Ο-/His263-Im+H and/or Carbonyl-Ο-/His263-Im+H, (b) the parameter k cat/Km equals to k1 and thus ES is formed and destroyed in the course of a series of consecutive reactions governed by the dynamic constant K S = k2/k1, and (c) the hydrolysis of substrate is assisted by a hydrogen bond developed between deprotonated Asp176 and the positively charged imidazole of His263 across a pKa-value 3.85, necessary for efficient catalysis

Non-parametric fitting of nonlinear equations to experi- mental data without use of initial guessing: a basic computer program

In this work, we present a non-parametric method, and the appropriate computer program, for fitting nonlinear multiparametric equations to experimental data. Our method is followed by computation of confidence limits of the parameter estimates. Its performance has been tested on several multiparametric equations, common in the fields of Biochemistry and Biotechnology, and it is a multiparametric expansion of the concept proposed by others for equations having more than two parameters. Good parameter estimates were obtained without a previous knowledge of initial parameter guessing values, and the proposed computer program converges rapidly, in all cases examined within this work.Neste trabalho, apresentamos um método não-paramétrico, e o programa de computação apropriado, para ajustar equações multiparamétricas não lineares para dados experimentais. Nosso método é seguido pelo cálculo dos limites de confiança dos parâmetros estimados. Seu desempenho tem sido testado em várias equações multiparamétricas, comuns nos campos da Bioquímica e Biotecnologia, e é uma expansão multiparamétrica do conceito proposto por outros, para equações que tenham mais de dois parâmetros. Obtivemos estimativas de parâmetros confiáveis sem um conhecimento prévio de parâmetros iniciais de valores esperados, e o programa de computação proposto converge rapidamente, em todos os casos examinados dentro deste trabalho