A temperature gradient incubator has been used to determine the effect of temperature on the growth of strains of Saccharomyces cerevisiae and Saccharomyces uvarum (including lager brewing yeasts formerly classified as Saccharomyces carlsbergensis).The maximum temperatures for growth (Tmox) for all strains of 5. cerevisiae examined were in the range 37-5°C-39-8°C and the optimum temperatures for the most rapid initial growth ( It is proposed, therefore, that the species name 5. carlsbergensis should be re-introduced and applied to those strains of S. uvarum (Group A) which have the lower Tmo* values.Minimum temperatures for growth (Tmin) of the yeasts were not investigated as initial studies had shown that they could not be measured satisfactorily.Measurements of the generation times for one brewing strain of S. cerevisiae and one brewing strain of 5. uvarum (Group A) over the temperature range 60°C-22 0°C have shown that there are significant differences between the yeasts at the lower end of the temperature range and that the relationship between generation time (GT) and temperature (T) for both yeasts closely follows the mathematical expression:Log (GT) = a + b (T) + c (T*)

It is proposed that the flocculation genes in Saccharomyces spp. hitherto referred to as FLO 1, FLO 2, and FLO 4 are ailelic and that they be consolidated into a single gene locus, to be known henceforth as FLO 1.

In this work, the effect of the concentration-dependent chemical-expansion coefficient, /?, on the chemo-elastic field in lithium-ion cathode particles is examined. To accomplish this, an isotropic linear-elastic model is developed for a single idealistic particle sub jected to potentiostatic-discharge and charge conditions. It is shown that p can be a key parameter in demarcating the chemo-stress-strain state of the cathode material under going nonlinear volumetric strains. As an example, such strains develop in the hexagonal-to-monoclinic-phase region of LixCoO 2 (0.37 < x< 0.55) and, subsequently, the corresponding p is a linear function of concentration. Previous studies have assumed a constant value for p. Findings suggest that the composition-generated chemo-elastic field that is based on a linear-p dramatically affects both the interdiffusion and the me chanical behavior of the LixCo02 cathode particle. Because the chemo-elastic phenom ena emanate in a reciprocal fashion, the resulting linear P-based hydrostatic-stress gradients significantly aid the diffusion of lithium. Thus, diffusion is accelerated in either electrochemical process that the cathode material undergoes.

Published information and experience of the genus Zymomonas is reviewed, and discussed with particular reference to the occurrence, detection and control of the organism in the fermentation industry.

Flash nanoprecipitation (FNP) is an efficient and scalable nanoparticle synthesis method that has not previously been applied to nanosensor fabrication. Current nanosensor fabrication methods have traditionally exhibited poor replicability and consistency resulting in high batch-to-batch variability, highlighting the need for a more tunable and efficient method such as FNP. We used FNP to fabricate nanosensors to sense oxygen based on an oxygen-sensitive dye and a reference dye, as a tool for measuring microbial metabolism. We used fluorescence spectroscopy to optimize nanosensor formulations, calibrate the nanosensors for oxygen concentration determination, and measure oxygen concentrations through oxygen-sensitive dye luminescence. FNP provides an effective platform for making sensors capable of responding to oxygen concentration in gas-bubbled solutions as well as in microbial environments. The environments we tested the sensors in are Pseudomonas aeruginosa biofilms and Saccharomyces cerevisiae liquid cultures—both settings where oxygen concentration is highly dependent on microbial activity. With FNP now applied to nanosensor fabrication, future nanosensor applications can take advantage of improved product quality through better replicability and consistency while maintaining the original function of the nanosensor.

A short review of the development of yeast genetics in general, and with respect to flocculation in particular, is presented. At least three genes, two dominant and one recessive, confer floccu lence, only one of these genes requiring to be present. The spontaneous gene mutation or mitotic segregation rates from flocculence to non-flocculence are high and are much higher than those rates in the reverse direction. Attempts were made to estimate the ploidy of some commercial strains of Saccharomyces cerevisiae by measurement of cell volume and DNA content.

A study has been made of the sporulating behaviour of twenty selected brewing strains of yeast, and the mating activity of the products of sporuiation. 'Lager' yeasts (strains of Saccharomyces carlsbergensis) in general sporuiated to a lesser degree and more slowly than 'ale' yeasts (strains of Saccharomyces cerevisfae) and produced 1 -or 2-spored asci compared with 2-or 3-spored asci for the latter yeasts. Most of the parent strains of S. cerevisiae were shown to be heterozygous for mating type, and they were all probably either triploid or aneuploid. Two of the strains of S. carlsbergensis were apparently homozygous for mating type and also triploid or aneuploid. The compatibility system favours outbreeding of yeasts, 'ale' yeasts being more compatible with 'lager' yeasts than with other 'ale' yeasts.

During the course of an investigation of Zymomonaa spp. in the brewing industry, a strain w w isolated from different habitats and identified as 2. mobilis. It is the f i s t occasion on which this species has been isolated from British beers. Closer examination of one isolate showed that it was different from the stock strain of 2. mobilis, both in vitamin requirements and serology. Strains of 2. anaerobia were also isolated and it was possible to induce these bacteria to metabolize sucrose. Since the ability to utilize this sugar is one of the major differences between 2. mobilis and 2. anaerobia, and in view of the closeness of the G+C ratios, the whole question of whether 2 species of Zymontonas are justified is thrown into doubt. UNLIKE MOST BACTERIA, Zymomonas spp. can carry out an alcoholic fermentation of certain simple sugars. The enzyme system by which this conversion is effected is not the Embden-Meyerhof-Parnas pathway of the yeasts and certain lactic acid bacteria, but the Entner-Doudoroff route. Unfortunately, during alcoholic fermentation Zymorrwnm spp. accumulate acetaldehyde, which imparts an undesirable fruity or apple-like aroma to the beer. Added to this, hydrogen sulphide may be produced which further damages aroma and flavour with its near putrid smell.It is generally agreed that there are 2 species of this organism called Zymomonas anaerobia and Z . rnobilis. The first of these has been found in beers and other British alcoholic beverages, whereas the latter has not hitherto been discovered in this habitat. Details of the differences between the 2 species have been described (Carr & Passmore, 1971). The major differences between them is in their sugar fermentations. Zymomonas anaerobia ferments only glucose and fructose, whereas Z . mobilis also can metabolize sucrose. It is probably the use of glucose, invert sugar and other carbohydrate mixtures to sweeten and promote secondary fermentation in British ales that, allows the organism to grow in this situation.Recently, and for the first time, strains of Z . mobilis were discovered in beer samples taken from places 150 miles apart. At least one of these strains appears to be