Effect of high hydrostatic pressure on the enzyme activities in Saccharomyces cerevisiae and Escherichia coli

Critical impact of pressure regulation on carbon dioxide biosynthesis

Carbon dioxide (CO2) biosynthesis is a promising alternative to traditional chemical synthesis. However, its application in engineering is hampered by poor gas mass transfer rates. Pressurization is an effective method to enhance mass transfer and increase synthesis yield, although the underlying mechanisms remain unclear. This review examines the effects of high pressure on CO2 biosynthesis, elucidating the mechanisms behind yield enhancement from three perspectives: microbial physiological traits, gas mass transfer and synthetic pathways. The critical role of pressurization in improving microbial activity and gas transfer efficiency is emphasized, with particular attention to maintaining pressure within microbial tolerance limits to maximize yield without compromising cell structure integrity.

High Hydrostatic Pressure in the Modulation of Enzymatic and Organocatalysis and Life under Pressure: A Review

The interest in high hydrostatic pressure (HHP) is mostly focused on the inactivation of deleterious enzymes, considering the quality-related issues associated with enzymes in foods. However, more recently, HHP has been increasingly studied for several biotechnological applications, including the possibility of carrying out enzyme-catalyzed reactions under high pressure. This review aims to comprehensively present and discuss the effects of HHP on the kinetic catalytic action of enzymes and the equilibrium of the reaction when enzymatic reactions take place under pressure. Each enzyme can respond differently to high pressure, mainly depending on the pressure range and temperature applied. In some cases, the enzymatic reaction remains significantly active at high pressure and temperature, while at ambient pressure it is already inactivated or possesses minor activity. Furthermore, the effect of temperature and pressure on the enzymatic activity indicated a faster decrease in activity when elevated pressure is applied. For most cases, the product concentration at equilibrium under pressure increased; however, in some cases, hydrolysis was preferred over synthesis when pressure increased. The compiled evidence of the effect of high pressure on enzymatic activity indicates that pressure is an effective reaction parameter and that its application for enzyme catalysis is promising.

An epidemiological analysis of Nocardia seriolae isolated from a wide range of aquatic animals in Taiwan, based on their genotype and enzymatic activity

Chronic disease following Nocardia seriolae infection in a wide range of aquatic animals has been reported in many Asian countries and recently in America and Mexico. This study aimed to investigate the epidemiological relationship among N. seriolae isolates in Taiwan by investigating their genotype and enzymatic activities. A total of 66 strains isolated from 14 known and four unknown host fish from five sites in Taiwan were characterized using five combined methods. High genotypic diversity was recognized among the isolates with 10 pulsotypes being identified from the pulsed-field gel electrophoresis method and 21 reptypes from the repetitive extragenic palindromic amplification method; however, no natural plasmids were detected in this bacterial population. Pulsotypes A8 and RI analysed by PFGE and repPCR, respectively, were found to be predominant within five sites in Taiwan over 17 years of isolation. Enzymatically, the majority of isolates displayed high leucine arylamidase, β-glucosidase and α-glucosidase activities but were negative for lipase, α-galactosidase, β-glucuronidase, N-acetyl-glucosaminidase, α-mannosidase and α-fucosidase activities. We identified a strong association between genotype and enzymatic activity since the majority of pulsotypes displayed the same type of enzymatic profile. This study provides comprehensive and potential epidemiological data, which will aid the fish farming activities and prevention method development.

Diversity and enzymatic profiles of indigenous yeasts isolated from three types of palm wines produced in Côte d'Ivoire

AIMS

To investigate the genotypic diversity and enzymatic activity of yeast flora isolated from spontaneous fermenting saps of various palm trees (Borassus aethiopum, Raphia hookeri, Elaeis guineensis) tapped for palm wines.

METHODS AND RESULTS

PCR-restriction fragment length polymorphism of ITS-5.8S rDNA combined to 26S rRNA gene and/or the partial ACT1 gene sequencing were applied for yeast characterization, and their enzymatic profiles assessed by using API ZYM kits. Thirteen genera and 23 species were identified, with the highest diversity (14 species) in raffia wine. Saccharomyces cerevisiae was dominant and common to all palm wines. Some potentially pathogenic yeasts were also isolated. The majority of tested strains displayed high amylo-peptidase, phosphatase, β-glucosidase and α-glucosidase activities and esterase activity.

CONCLUSIONS

Diverse yeast species colonized palm wines, among which some were related to a specific type of wine and the majority of them have the ability to digest starch, sugar, protein or lipid.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is a first step in understanding the significance of indigenous yeast flora of palm wines from Côte d'Ivoire. This knowledge is important as a tool for establishing new indigenous yeast collection; which could be used for the product quality improvement and as enzyme sources for biotechnological purposes.

Microbial production of metabolites and associated enzymatic reactions under high pressure

High environmental pressure exerts an external stress on the survival of microorganisms that are commonly found under normal pressure. In response, many growth traits alter, including cell morphology and physiology, cellular structure, metabolism, physical and chemical properties, the reproductive process, and defense mechanisms. The high-pressure technology (HP) has been industrially utilized in pressurized sterilization, synthesis of stress-induced products, and microbial/enzymatic transformation of chemicals. This article reviews current research on pressure-induced production of metabolites in normal-pressure microbes and their enzymatic reactions. Factors that affect the production of such metabolites are summarized, as well as the effect of pressure on the performance of microbial fermentation and the yield of flavoring compounds, different categories of induced enzymatic reactions and their characteristics in the supercritical carbon dioxide fluid, effects on enzyme activity, and the selection of desirable bacterial strains. Technological challenges are discussed, and future research directions are proposed. Information presented here will benefit the research, development, and application of the HP technology to improve microbial fermentation and enzymatic production of biologically active substances, thereby help to meet their increasing demand from the ever-expanding market.

Combined effects of high-pressure and thermal treatments on lipid oxidation and enzymes in pork

The relationship between lipid oxidation and related enzymes in pork during combined pressure-heat treatments was investigated. Minced pork was treated under a pressure range of 0.1-750 MPa and a temperature range of 30-60°C for 20 min. Thiobarbituric acid-reactive substances (TBARS) values and activities of acid lipase (AL), neutral lipase (NL), phospholipase (PL), and lipoxygenase (LOX) in pork were evaluated. NL and LOX were completely inactivated at 600 MPa-50°C and 450 MPa-60°C, and AL at 600MPa-55°C. PL had the greatest stability and was completely inactivated at 600 MPa-60°C and 750 MPa-50°C. PL activity was strongly related to lipid oxidation caused by high pressure, followed by AL and LOX. TBARS values at 600 and 750 MPa were strongly related to the inactivation rate and the ratio of PL during treatment. PL was the most important enzyme related to lipid oxidation induced by pressure.