Makoto Kanauchi

Release of β-Glucan from Cell Walls of Starchy Endosperm of Barley

ABSTRACT β-Glucan can be solubilized from barley by warm water, with increasing solubilization as the temperature is increased. Substantially less glucan is extracted if the barley is dehusked using sulfuric acid, particularly if the dehusked barley is denatured. This indicates that enzymes capable of solubilizing glucan are present in barley. Various purified enzymes promote the solubilization of glucan from denatured and dehusked barley. Apart from endo-β-(1→3)(1→4)-glucanase, these enzymes include endo-xylanases, arabinofuranosidase, xyloacetylesterase, and feruloyl esterase. Ferulic acid and, probably, acetyl groups are esterlinked to arabinoxylan, not β-glucan, in the cell walls of barley starchy endosperm, so the ability of the esterases, xylanases, and arabinofuranosidase to solubilize glucan indicates the pentosan component of the cell wall can restrict the extraction of glucan.

Use of novel assays to indicate that O-esters and S-esters are produced by the same enzyme in brewing yeast

Ethanol- and methanethiol-dependent removal of acetyl-CoA by crude extracts of ale yeast has been monitored using a decrease in OD232. Activity has also been detected in these extracts after fractionation on polyacrylamide gels, in this case using a novel assay in which the coenzyme A produced in the reaction is linked via DCPIP reduction to color formation from nitroblue tetrazolium. Ethanol- and methanethiol-dependent activities migrate identically on such gels, and only one band of color formation was observed. Furthermore they displayed closely similar sensitivity to heating at 40 degrees C and 60 degrees C and pH optima, with activity maximal at pH 7.5. It is likely that a single enzyme is responsible for the formation of O-esters and S-esters in yeast. Initial kinetic studies indicate that methanethiol has higher affinity for the enzyme than has ethanol and a higher maximum velocity. However, the enzyme has a much lower Km for acetyl-CoA, suggesting that the alcohol or thiol substrate is the more likely substrate to be limiting.

Isolation of Endotoxin Eliminating Lactic Acid Bacteria and a Property of Endotoxin Eliminating Protein.

Recently, many scholars have reported lactic acid bacteria (LAB) functions, such as anticancer activity and anti-inflammatory activity for intestines. To decrease inflammatory substances such as endotoxins, LAB consumed safely with meals were isolated from food and food ingredients. First, LAB were isolated as 168 strains of bacillus LAB (49 strain) and coccus LAB (119 strains) from food ingredients and fermented foods such as rice, rice bran, malt, grains, miso soy paste, and some pickles. Their LAB (168 strains) were cultivated in medium containing endotoxin from Escherichia coli O18 LPS at 15 and 30 °C for 64 h to identify endotoxin-eliminating LAB. Consequently, the AK-23 strain was screened as an endotoxin-eliminating LAB strain. The strain decreased endotoxin in YP medium without sugar at 30 °C for 64 h until 9% of endotoxin. The strain was identified as Pediococcus pentosaceus according to morphological characteristics such as its cell shape, physiological characteristics related to its fermentation type, assimilation of sugars, pH tolerance, optimum growth temperature, and molecular biological characteristics as its homology to 16S rRNA. To investigate the location of the endotoxin-eliminating substance, 4 fractions were separated from AK-23 cells as extracellular, cell wall digestion, cytoplasm, and cell membrane fractions. The endotoxin-decreasing substance, located on a cell wall, was identified as a 217 kDa protein.

Screening the Hydroxylation of Fatty Acids with Lactic Acid Bacteria Based on the Lactonization of the Hydroxylated Products

Hydroxyl fatty acids (HFAs) are used for the production of artificial food flavorings and alcoholic beverages. In this study, we screened a series of hydroxylating lactic acid bacteria (LAB) by using a rapid screening method based on the lactonization of the products with brewing yeast. γ-Lactones have a fruity aroma with a low detection threshold, meaning that they can be readily detected by sniffing without the need for GC-MS analysis. LAB can be used to hydroxylate fatty acids, which can be lactonized with brewing yeast for detection with the sniffing method. Commercial yeast strains were cultivated in the presence of HFAs, and lactone-producing strains were detected by sniffing. Beer brewing yeast T-58 gave the highest level of γ-lactone from ricinoleic acid (>90%). Strains of LAB capable of converting unsaturated fatty acids to HFAs were screened with T-58 yeast. The Y-20 strain was determined to be the best LAB and converted oleic acid to 10-hydroxystearic acid. It was subsequently identified as Lactobacillus sakei. Notably, this LAB hydroxylated over 90% of the oleic acid in the medium at 15°C after 30–48 h. These results therefore suggest that the Y-20 strain could be used to hydroxylate fatty acids for alcoholic beverages.

New Cheese-Like Food Production from Soy Milk — Utility of Soy Milk Curdling Yeast

Soybeans are a traditional food in eastern Asia, particularly in Japan and China. They were eaten in 100 BC in China. The beans can be processed into Tofu, soy milk, fermented seasonings, soy sauce or Miso paste, and Natto and green beans. Soybeans have rich nutrition, protein lipid, and other functional substances such as isoflavones. However, soybeans are difficult to process for use as food because of tissue and cell wall hardness. Therefore, soybeans are conducted to do some treatments, e.g., boiling, steaming, roasting, crushing/grinding, and some enzyme treating, to eat soy protein easily. Soy storage proteins mainly comprise two proteins as 7S globulin composed with β-conglycinin and 11S globulin containing glycinin composed of 5 subunits. βConglycinin, included in 7S globulin, is composed of three subunits. To modify the physical properties of soy protein, a new type of enzyme for curdling soybean milk enzyme was purified as an extract from yeast. Yeast producing curdling soybean milk enzyme, the SCY003 strain, was isolated from 1345 yeast strains. According to the morphology, physiology, and molecular and characteristics, SCY003 was identified as Saccharomyces bayanus. The soy milk curdling enzyme having proteolytic activity was approximately 45 kDa and monomer protein. The optimum pH for the protease activity was pH 7.5; the optimum temperature was 50°C. The enzyme cleaved the β-conglycinin as α–, α′-, and part of glycinin as A3 A4, A1b, and A2 in soy protein by endoproteolysis. Soybean protein became loosely curdled with the addition of other proteases from microorganisms or plants. Soybean milk curdled after cleaving endoproteolysis enzyme in SCY003 strain.

Neutralization of Lipopolysaccharide by Heat Shock Protein in Pediococcus pentosaceus AK-23

About 1000 species of bacteria are present in the human intestine. Some Gram-negative bacteria such as Escherichia coli or Salmonella spp. among intestinal bacteria have lipopolysaccharide (LPS), which might induce inflammation of human intestines. Actually, LPS, especially its lipid A constituent, is toxic. Small amounts of LPS in bacteria cause inflammation of mucosa and other tissues in humans. Such bacteria may be regulated by beneficial lactic acid bacteria to maintain human health. Many lactic acid bacteria show cancer prevention activity and anti-inflammatory activity in intestines. Recently, Pediococcus pentosaceus AK-23 was isolated from fermentative vegetable pickles for neutralization of LPS. For this study, a protein for LPS neutralization was purified partly from P. pentosaceus AK-23. For this study, a protein for LPS neutralization was purified partly from P. pentosaceus AK-23, by ultrafiltration using a 300 kDa membrane and a 100 kDa membrane after cell wall digestion by lysozyme. Gel running blue native electrophoresis revealed the existence of a 217 kDa protein. The band of the protein having the ability to bind LPS on the gel was analyzed for amino acid homology. As the result, it is revealed as part of a subunit of heat shock protein (HSP). Furthermore, it displayed LPS binding or hydrophobic motifs. The protein neutralized LPS to release fatty acid as myristic acid and glucose from polysaccharide. These findings suggest that HSP in P. pentosaceus AK-23 neutralizes LPS to decompose it compising fatty acid and polysaccharide.