Role of Leuconostoc mesenteroides in Leavening the Batter of Idli, a Fermented Food of India

The fermentation of the batter of idli, a fermented food of India, was studied. The microorganisms responsible for the characteristic changes in the batter were isolated and identified. Although there is a sequential change in the bacterial flora, the predominant microorganism responsible for souring, as well as for gas production, was found to be Leuconostoc mesenteroides. In the later stages of fermentation, growth of Streptococcus faecalis and, still later, of Pediococcus cerevisiae becomes significant. The fermentation of idli demonstrates a leavening action caused by the activity of the heterofermentative lactic acid bacterium, L. mesenteroides. As far as is known, this is the first record of a leavening action produced exclusively by the activity of a lactic acid bacterium.     

Isolation and properties of polyribosomes and fragments of the endoplasmic reticulum from rat liver

1. A centrifugation method for the fractionation of the postmitochondrial fraction from rat-liver homogenates is described. The technique, in which no detergent is used, may be used as a tool to discriminate between two classes of ribosomes. One class is firmly bound to membranes and the other consists either of free polysomes or of ribosomes attached by weaker forces to the membranes of the endoplasmic reticulum. 2. Electron-micrograph studies revealed that the polysomes were not contaminated with bound ribosomes or with membranous fragments. 3. The separated fractions were characterized by their RNA, protein, ribonuclease and phospholipid content. 4. The influence of starvation on the RNA and protein contents of the different fractions was investigated. 5. Labelling of the various centrifugal fractions in vivo revealed no difference in uptake of radioactive amino acid between the two classes of ribosomes. 6. Incorporation of radioactive leucine in vitro and the polyuridylic acid-directed phenylalanine incorporation were similar for both classes of ribosomes.     

Changes in fungi with age. II. Respiration and respiratory enzymes of Rhizoctonia solani and Sclerotium bataticola

Van Etten, James L. (University of Illinois, Urbana), H. Peter Molitoris, and David Gottlieb. Changes in fungi with age. II. Respiration and respiratory enzymes of Rhizoctonia solani and Sclerotium bataticola. J. Bacteriol. 91:169-175. 1966.-The rate of respiration of Rhizoctonia solani and Sclerotium bataticola decreased with age. This decrease in respiratory rate might be produced by a decrease in the specific activity of one or more enzymes involved in carbohydrate metabolism. Specific activities in cell-free extracts were measured for most of the enzymes in the hexose monophosphate shunt, Embden-Meyerhof-Parnas pathway, tricarboxylic acid cycle, and terminal electron-transport system. In addition, glucose oxidase, isocitritase, and malic enzyme were measured. In R. solani, increases in activity with age occurred for hexokinase, alpha-glycerolphosphate dehydrogenase, malic dehydrogenase, and cytochrome oxidase. Decreases occurred for phosphohexokinase, aconitase, nicotinamide adenine dinucleotide-specific isocitric dehydrogenase, reduced nicotinamide adenine dinucleotide oxidase, and at least one of the enzymes between 3-phosphoglycerate and pyruvate. In S. bataticola, increases in activity with age were observed for phosphohexokinase, pyruvic dehydrogenase, fumarase, malic dehydrogenase, and malic enzyme, whereas none of the enzymes decreased. The specific activities of the remaining enzymes did not change with age in either fungus.