THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

https://www.mdpi.com/1422-0067/16/9/20774/pdf

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

Xanthan gum is a microbial exo-polysaccharide produced industrially from carbon sources by fermentation using the Gram-negative bacterium Xanthomonas campestris. The yield and properties of xanthan gum production and its applications in food are influenced by several variables. Knowing these variables is now needed and will be useful for the scale up production of xanthan gum to achieve high-quality gum at a low price. There have been attempts to optimize variables in xanthan gum production by using various raw materials. This review represents comprehensive knowledge about optimization of effective variables on production and structure of high quality xanthan gum and the applications of xanthan gum for enhancing the quality of foods.

Effective variables on production and structure of xanthan gum and its food applications: A review

Microorganisms directly and indirectly contribute to production of diverse biofuels. Heterotrophic microorganisms are being used for commercial production of biofuels such as biogas and fuel alcohols from organic matter. Photosynthetic microorganisms convert inorganic carbon and water to potential fuels (e.g. fuel alcohols, biohydrogen) and fuel precursors (e.g. biomass, starch, lipids). Only a few microbial processes are used for commercial production of biofuels, but this will certainly change with the enhanced production capabilities being achieved through microbial metabolic engineering. Processes that previously required multiple steps of feedstock pretreatment and subsequent conversion to fuel are being consolidated into single-step microbial processes using metabolically engineered species. Microorganisms with the ability to produce fuels from feedstock they could not use previously, are being engineered. This review discusses some of the metabolic engineering approaches being used to enhance the commercialization potential of microbial biofuels including fuel alcohols, biodiesel and biohydrogen. At present, all biogas production relies on native populations of methanogens and this does not seem likely to change in the near term. Potential fuels from microalgae, cyanobacteria and other photosynthetic bacteria, whether native or engineered, have distant prospects of commercial use. Metabolically engineered yeasts surface displaying various hydrolytic enzymes appear to hold the greatest potential for near term commercial use in generating bioethanol from starch, pretreated lignocellulose and other polysaccharides. The bacterium Zymomonas mobilis metabolically engineered to make bioethanol from pentose sugars is already being commercialized. Other similar examples are likely to emerge as more engineered microorganisms become available.

Metabolic engineering of microorganisms for biofuel production

Microbial exopolysaccharides (EPS) are an abundant and important group of compounds that can be secreted by bacteria, fungi and algae. The biotechnological production of these substances represents a faster alternative when compared to chemical and plant-derived production with the possibility of using industrial wastes as substrates, a feasible strategy after a comprehensive study of factors that may affect the synthesis by the chosen microorganism and desirable final product. Another possible difficulty could be the extraction and purification methods, a crucial part of the production of microbial polysaccharides, since different methods should be adopted. In this sense, this review aims to present the biotechnological production of microbial exopolysaccharides, exploring the production steps, optimization processes and current applications of these relevant bioproducts.

Current status of biotechnological production and applications of microbial exopolysaccharides

Direct production of acetone–butanol–ethanol from waste starch by free and immobilized Clostridium acetobutylicum

Cheese whey lactose was used as a carbon source for xanthan gum production with Xanthomonas campestris and Xanthomonas pelargonii. Proteins were precipitated and removed from whey prior to fermentation. Box-Behnken response surface methodology was used for optimization of the carbon, magnesium, and phosphate source concentrations in the culture medium to maximize xanthan gum production. After 48 h of fermentation using X. campestris, the highest xanthan concentration (16.4 g/L) was achieved at 65.2 g/L of cheese whey (39.1 g/L of lactose), 14.8 g/L of phosphate (K H2PO4), and 1.1 g/L of magnesium (MgSO4·7H2O). The corresponding optimum cheese whey, phosphate, and magnesium concentrations in cultures of X. pelargonii were 80.0, 6.7, and 0.8 g/L, respectively, which resulted in a xanthan production of 12.8 g/L. The xanthan gum yield (g of xanthan/g of lactose) was 0.42 for X. campestris and 0.27 for X. pelargonii.

Optimization of xanthan gum production using cheese whey and response surface methodology

Cell-surface display is the expression of peptides and proteins on the surface of living cells by fusing them to functional components of cells which are exposed to the environment of cells. This strategy can be carried out using different surface proteins of cells as anchoring motifs and different proteins from different sources as a passenger protein. It is a promising strategy for developing novel whole cell factories. Surface engineered cells have many potential uses ranging from medical to environmental applications. This review focuses on different strategy and applications of micro

http://www.ijbiotech.com/article_7171_54a154fd2b34e89985489edeaf46bb3a.pdf

Microbial cell surface display; its medical and environ- mental applications

Recurrent aphthous stomatitis (RAS) is one of the most common oral mucosa lesions seen in primary care. RAS is a pathologic condition characterized by recurring, painful, small oral mucosal ulcers with a round or oval aspect, clean borders. The aim of this study was to recognize the effect of a new mixed herbal medicine on minor RAS as a treatment, which is more effective and has fewer side effects. This study was done by double blind method. 38 patients without any systematic illness were investigated in two groups: case group (19 patients) and blank treatment (19 patients). A new mixed herbal medicine was used for both the groups. This medicine includes Rosa damascena, Melissa officinalis, Quercus robur and Portulaca olearaceae. The results showed an effective treatment for minor aphthous ulcers through using the four herbal products which showed a shorter healing period with fewer side effects.

Production of a new mixed herbal medicine for minor Aphthous Ulcers

The yeast Saccharomyces cerevisiae is able to biotransform benzaldehyde into L-phenylacetylcarbinol (L-PAC), a key intermediate in the production of ephedrine and pseudoephedrine, by the action of pyruvate decarobxylase (PDC) enzyme. This biotransformation can alternatively be performed by acetohydroxyacid synthase (AHAS) which is a mitochondrial enzyme. In the yeast petite mutants, AHAS accumulates in the cytosol. In the current study, wild-type yeast cells and yeast petite mutants were examined for L-PAC biosynthesis. The results showed higher L-PAC titers in the yeast petite mutants. In addition, the effect of cell immobilization and carbon source (glucose or molasses) on L-PAC production was investigated. It was found that cell immobilization enhances L-PAC formation. The highest L-PAC concentration (2.4 g/l) was obtained at 2 g/l of benzaldehyde using the immobilized petite mutants grown on molasses.

Mohsen Doostmohammadi

Papers

Direct production of acetone–butanol–ethanol from waste starch by free and immobilized Clostridium acetobutylicum

Optimization of xanthan gum production using cheese whey and response surface methodology

Microbial cell surface display; its medical and environ- mental applications

Production of a new mixed herbal medicine for minor Aphthous Ulcers

L-phenylacetylcarbinol production by yeast petite mutants