Eurypsychrophilic acidophiles: From (meta)genomes to low-temperature biotechnologies

Extremophilic Microorganisms as a Source of Emerging Enzymes for the Food Industry: A Review

Modern-day consumers are interested in highly nutritious and safe foods with corresponding organoleptic qualities. Such foods are increasingly subjected to various processing techniques which include the use of enzymes. These enzymes like amylases, lipases, proteases, xylanases, laccases, pullulanase, chitinases, pectinases, esterases, isomerases, and dehydrogenases could be derived from extremophilic organisms such as thermophiles, psychrophiles, acidophiles, alkaliphiles, and halophiles. As these organisms can grow under severe environmental conditions, they can produce functional enzymes (extremozymes) used in producing safe foods (such as gluten-free, lactose-free, lower acrylamide, or lower trans-fat products). The extremozymes also enhance nutrient bioavailability and bioaccessibility (e.g., predigested nourishments like baby formulae), and improve nourishment functionalities such as surface, sensory, and bioactive properties. Therefore, exploring alternative sources of enzymes for better compatibility and long-term adaptability in the processing stages is a promising approach for obtaining novel food products. This review will establish novel discovery methods of extremozymes from psychrophiles, thermophiles, acidophiles, alkaliphiles, and halophiles, the enzymes' types, mechanisms of action, and their food applications. It will also contribute to their commercial relevance and the furtherance of their discovery.

Methods for studying microbial acid stress responses: from molecules to populations

The study of how micro-organisms detect and respond to different stresses has a long history of producing fundamental biological insights while being simultaneously of significance in many applied microbiological fields including infection, food and drink manufacture, and industrial and environmental biotechnology. This is well-illustrated by the large body of work on acid stress. Numerous different methods have been used to understand the impacts of low pH on growth and survival of micro-organisms, ranging from studies of single cells to large and heterogeneous populations, from the molecular or biophysical to the computational, and from well-understood model organisms to poorly defined and complex microbial consortia. Much is to be gained from an increased general awareness of these methods, and so the present review looks at examples of the different methods that have been used to study acid resistance, acid tolerance, and acid stress responses, and the insights they can lead to, as well as some of the problems involved in using them. We hope this will be of interest both within and well beyond the acid stress research community.

Helping proteins come in from the cold: 5 burning questions about cold-active enzymes

Enzymes from psychrophilic (cold-loving) organisms have attracted considerable interest over the past decades for their potential in various low-temperature industrial processes. However, we still lack large-scale commercialization of their activities. Here, we review their properties, limitations and potential. Our review is structured around answers to 5 central questions: 1. How do cold-active enzymes achieve high catalytic rates at low temperatures? 2. How is protein flexibility connected to cold-activity? 3. What are the sequence-based and structural determinants for cold-activity? 4. How does the thermodynamic stability of psychrophilic enzymes reflect their cold-active capabilities? 5. How do we effectively identify novel cold-active enzymes, and can we apply them in an industrial context? We conclude that emerging screening technologies combined with big-data handling and analysis make it reasonable to expect a bright future for our understanding and exploitation of cold-active enzymes.