Starters and Bacteriophages in Lactic Acid Casein Manufacture

1975 ◽  
Vol 38 (5) ◽  
pp. 275-278 ◽  
Author(s):  
T. D. THOMAS ◽  
R. J. LOWRIE
Keyword(s):  
Lactic Acid ◽  
New Zealand ◽  
Acid Production ◽  
Continuous Selection ◽  
Streptococcus Cremoris ◽  
Selection For ◽  
The Individual ◽  
First Time ◽  
Selection Of

A controlled starter system was used for the first time in commercial lactic acid casein manufacture in New Zealand. Multiple starters of up to four components were constructed from 18 recently derived Streptococcus cremoris isolates which were not lysed by any of the phages in the collection of the New Zealand Dairy Research Institute. During the first season of casein manufacture, phages attacking 17 isolates were detected in the casein whey. Of these, 12 prevented adequate acid production by the appropriate host even at levels below 1 phage per 10 to 1000 ml in the milk before starter addition. In contrast, the first detected phages attacking the other five isolates did not significantly influence the rate of acid development; use of these starters continued until phages which eliminated acid production appeared. An alternative starter system based on the continuous selection of “phage-tolerant” cultures was investigated. Regular addition of whey, from previous manufacture, to the individual mother cultures of each component permitted long-term use of the multiple starter. This procedure of continued selection for phage-tolerant organisms has been used successfully for a complete season in a major casein factory.

Starters and Bacteriophages in Lactic Acid Casein Manufacture

1975 ◽  
Vol 38 (5) ◽  
pp. 269-274 ◽  
Author(s):  
T. D. THOMAS ◽  
R. J. LOWRIE
Keyword(s):  
Lactic Acid ◽  
Acid Production ◽  
Milk Proteins ◽  
Maximum Cell Density ◽  
Predominant Species ◽  
Streptococcus Cremoris ◽  
Maximum Cell ◽  
Cell Densities ◽  
Total Bacteria ◽  
Selection Of

The bacteriological composition and acid producing activity of mixed strain starters used for commercial lactic acid casein manufacture were investigated. Rates of acid production by mixed starters from eight New Zealand casein factories were similar under standard laboratory conditions. Streptococcus cremoris was the predominant species comprising some 70–90% of total bacteria in all but one mixed casein starter. Most isolates in a random selection of 160 individual S. cremoris colonies took longer than the parent mixed starter to coagulate autoclaved skimmilk at 22 C. More than half required 2–3 days and some up to 7 days of incubation, in contrast to the 17–20 h required by the mixed starters. Only 20% of the S. cremoris isolates had the coagulation times and reached maximum cell densities characteristic of the parent mixed cultures. The slow-coagulating isolates grew to only low population densities in milk although acid production continued in stationary-phase cultures. The maximum cell density and rate of acid production could be increased by culturing together with a fast-coagulating strain, by addition of hydrolysed milk proteins or amino acids. Whey samples from the casein precipitation silos of eight commercial factories were examined for bacteriophage. Virulent phages were found in all samples.

A single-round selection of selective DNA aptamers for mammalian cells by polymer-enhanced capillary transient isotachophoresis

The Analyst ◽  
2017 ◽  
Vol 142 (21) ◽  
pp. 4030-4038 ◽  
Author(s):  
Kazuki Hirose ◽  
Maho Tsuchida ◽  
Hinako Asakura ◽  
Koji Wakui ◽  
Keitaro Yoshimoto ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Mammalian Cells ◽  
Dna Aptamer ◽  
Dna Aptamers ◽  
Aptamer Selection ◽  
Selection For ◽  
First Time ◽  
Selection Of

A single-round DNA aptamer selection for mammalian cells was successfully achieved for the first time using a capillary electrophoresis (CE)-based methodology.

Problems of amenity grass seed production in New Zealand

1980 ◽  
Vol 1 ◽  
pp. 26-30
Author(s):  
L. Corkill ◽  
W. Rumball
Keyword(s):  
New Zealand ◽  
The Netherlands ◽  
Seed Production ◽  
Direct Selection ◽  
Usual Practice ◽  
Grass Seed ◽  
Breeding Management ◽  
Selection For ◽  
Seed Yields ◽  
Selection Of

The problems of seed production of amenity grasses in New Zealand are considered from two aspects - (a) increasing seed potential by breeding; (b) achieving that potential by good management as practised in the Netherlands, (a) In terms of breeding, the strategies to increase seed yield depended to some degree on the species concerned. With browntop it was necessary to discard about two-thirds of the most promising genotypes because of poor heading, but the remaining genotypes flowered freely and in unison, and gave good seed yields. With fescue even the best original plants were sparsely heading, so direct selection for prolificacy has been needed. This was also carried out for perennial ryegrass, as well as selection of early-heading genotypes to avoid infection by stem rust. (b) It is suggested that areas for seed of amenity grasses in New Zealand should be used for seed production only rather than for both forage and seed as is the usual practice. Techniques used in the Netherlands could serve as guidelines to procedures. The implications of low seeding rates, good weed control, high fertilizer applications and minimum cutting or grazing in promoting strong individual plants capable of high seed yields are discussed. Keywords: Amenity grass, seed production, New Zealand, breeding, management, Netherlands, Agrostis tenuis, Festuca rubra, Lolium perenne

scholarly journals Optimum selection intensities in artificial selection programmes: an experimental evaluation

1977 ◽  
Vol 30 (2) ◽  
pp. 115-119 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Experimental Evaluation ◽  
Selection Intensity ◽  
Effective Population ◽  
Term Selection ◽  
Optimum Selection ◽  
Selection For ◽  
Selection Intensities ◽  
Selection Of ◽  
Better Than

SUMMARYAn experimental evaluation of Robertson's (1970) theory concerning optimum intensities of selection for selection of varying durations has been carried out using published results from a long term selection study in Drosophila. Agreement of predicted rankings of treatments with expectations was excellent for low values of t/T (generations/total number scored) but poor for larger values of t/T. This was due to the 20% selection intensity treatments responding worse than expected and the 40% treatments relatively better than expected. Several possible reasons for the discrepancies exist but the most likely explanation is considered to be the greater reduction in effective population size due to selection in treatments with more intense selection.

Selection of indicator species for State of the Environment reporting: A case study from New Zealand

2010 ◽  
Vol 16 (2) ◽  
pp. 76 ◽  
Author(s):  
Joanne M. Hoare ◽  
Colin F. J. O’Donnell ◽  
Elaine F. Wright
Keyword(s):  
New Zealand ◽  
Indicator Species ◽  
Species Concepts ◽  
Monitoring Data ◽  
Environmental Reporting ◽  
Environmental Attributes ◽  
State Of The Environment ◽  
Selection Of

Indicator species approaches are widely used in conservation as a shortcut to measuring attributes of species and ecosystems. A variety of indicator species concepts are in use and are applicable to a range of situations. Indicator species are increasingly being used in environmental reporting to evaluate trends in environmental attributes quantitatively. We use the most recent State of the Environment report from New Zealand as a case study to evaluate: (1) how indicator species concepts are being applied to environmental reporting and (2) the selection of individual species as indicators. At present indicator species used in environmental reporting in New Zealand reflect biases in national monitoring data towards forest-dwelling, terrestrial vertebrates that are vulnerable to predation by introduced mammals. Scientific literature generally supports links between selected taxa and the aspect of ecosystem health they are purported to indicate, but their roles as long-term indicators of environmental health have yet to be evaluated. A primary goal of State of the Environment reporting is to set a benchmark against which environmental outcomes can be monitored over time; thus it is recognized that taxa reported should represent a broader range of environmental attributes. However, selection of taxa for environmental reporting is severely constrained by limited national species monitoring data. A strategic approach to national measurement, storage and analysis of long-term monitoring data is required to support selection of representative species for environmental reporting. We support current initiatives to select taxa for future measurement and reporting in an objective, transparent manner and recommend that they encompass representation of: (1) taxonomic diversity, (2) ecosystem types, (3) key environmental pressures and (4) threat status.

295. The problem of bacteriophage in cheese making: Part I. Observations and investigations on slow acid production

1942 ◽  
Vol 13 (1) ◽  
pp. 58-72 ◽  
Author(s):  
E. B. Anderson ◽  
L. J. Meanwell
Keyword(s):  
Lactic Acid ◽  
New Zealand ◽  
Acid Production ◽  
Single Strain ◽  
Pasteurized Milk ◽  
Cheese Making ◽  
Source Of Infection ◽  
Sudden Failure ◽  
Probable Source ◽  
Specific Bacteriophage

That bacteriophage is the cause of much loss to the cheese-making industry of New Zealand has been shown by Whitehead(1). In New Zealand in recent years, cheese has been made almost entirely from flash-pasteurized milk with the aid of starters prepared from single-strain cultures of lactic acid streptococci (Str. cremoris). The use of such starters has been accompanied by the occasional failure of the bulk starter to clot, or, if clotted, by failure to produce the required amount of acid in the cheese vat—the latter condition being described by Whitehead as ‘pack up’. Whitehead has traced the cause of sudden failure to air-borne infection of the bulk starter by specific bacteriophage (2), the most probable source of infection being the spray from whey separators. When adequate protection from phage contamination was provided slowness in cheese making disappeared.

scholarly journals How adaptive plasticity evolves when selected against

2018 ◽  
Author(s):  
Alfredo Rago ◽  
Kostas Kouvaris ◽  
Tobias Uller ◽  
Richard Watson
Keyword(s):  
Natural Selection ◽  
Environmental Change ◽  
Coarse Grained ◽  
Adaptive Plasticity ◽  
Short Term ◽  
Local Optima ◽  
Term Selection ◽  
Selection For ◽  
The Individual

AbstractAdaptive plasticity allows organisms to cope with environmental change, thereby increasing the population’s long-term fitness. However, individual selection can only compare the fitness of individuals within each generation: if the environment changes more slowly than the generation time (i.e., a coarse-grained environment) a population will not experience selection for plasticity even if it is adaptive in the long-term. How does adaptive plasticity then evolve? One explanation is that, if competing alleles conferring different degrees of plasticity persist across multiple environments, natural selection between lineages carrying those alleles could select for adaptive plasticity (lineage selection).We show that adaptive plasticity can evolve even in the absence of such lineage selection. Instead, we propose that adaptive plasticity in coarse-grained environments evolves as a by-product of inefficient short-term natural selection. In our simulations, populations that can efficiently respond to selective pressures follow short-term, local, optima and have lower long-term fitness. Conversely, populations that accumulate limited genetic change within each environment evolve long-term adaptive plasticity even when plasticity incurs short-term costs. These results remain qualitatively similar regardless of whether we decrease the efficiency of natural selection by increasing the rate of environmental change or decreasing mutation rate, demonstrating that both factors act via the same mechanism. We demonstrate how this mechanism can be understood through the concept of learning rate.Our work shows how plastic responses that are costly in the short term, yet adaptive in the long term, can evolve as a by-product of inefficient short-term selection, without selection for plasticity at either the individual or lineage level.

CHEESE-RIPENING STUDIES: THE INFLUENCE OF THE CONFIGURATIONAL RELATIONS OF THE HEXOSES ON THE SUGAR-FERMENTING ABILITIES OF LACTIC ACID STREPTOCOCCI: A Preliminary Note

1936 ◽  
Vol 14b (9) ◽  
pp. 320-324 ◽  
Author(s):  
Olga Okulitch ◽  
Blythe Alfred Eagles
Keyword(s):  
Lactic Acid ◽  
Acid Production ◽  
Carbon Sources ◽  
Preliminary Note ◽  
Cheese Ripening ◽  
Inhibiting Effect ◽  
Streptococcus Cremoris ◽  
Gradual Loss ◽  
Metabolic Products ◽  
Produce Acid

The influence of the configurational relations of the hexoses on the ability of a Streptococcus cremoris strain to produce acid from lactose in milk and in broth has been studied.With casein digest broth as the nitrogen source, the organism was carried by serial transfers in 10 different carbon sources; at every transfer the cultures were inoculated from the sugar broths into milk, and the clotting times of the respective milk tubes determined.The carrying of the culture in sucrose, maltose, dextrin or starch has no influence on the acid-producing ability of the organism.Glucose, mannose, fructose, and salicin exhibit a marked inhibiting effect on the rate and amount of acid production in milk and in lactose broth.Although galactose and lactose fail to inhibit completely the activity of the organism, a restraining influence on acid production is to be observed. It is suggested that the inhibitory activity of glucose or one of its metabolic products may be a cause of the sudden or gradual loss of vitality in starters.

CHEESE-RIPENING STUDIES: THE INFLUENCE OF DIFFERENT EXTRACTS ON THE ACID PRODUCTION OF LACTIC ACID BACTERIA

1936 ◽  
Vol 14b (5) ◽  
pp. 139-150 ◽  
Author(s):  
Wilfrid Sadler ◽  
Blythe Alfred Eagles ◽  
John Francis Bowen ◽  
Alexander James Wood
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Acid Production ◽  
Vital Activity ◽  
Forage Crops ◽  
Forage Crop ◽  
Cheese Ripening ◽  
Streptococcus Cremoris ◽  
Broth Enrichment

The influence of different extracts on the acid production of two strains of Streptococcus cremoris and two of Betacoccus cremoris isolated from Kingston cheese has been studied.The enriching entity has no effect on acid production by Streptococci in sugar broth. Enrichment with yeast or alfalfa extract causes not only a marked increase in the acid production by Betacocci, but also a definite stimulating effect on the rate of acid production.Enriching milk with yeast or alfalfa extract has a marked stimulating effect on the vital activity of the Betacocci and of Streptococcus EMB1173, but is without influence on Streptococcus EMB1195. The response of culture EMB1173 is immediate and direct, but in the case of cultures EMB2168 and EMB2173 the action of the enriching entity is cumulative in its effect. Alfalfa extract would appear to provide, in the case of Betacoccus EMB2173, a stimulating influence not to be found in yeast extract.The influence of other forage crop enrichments on rate of acid production has also been studied. The factor or factors present in alfalfa and shown to exert a stimulating influence on the vital activity of the organisms are to be found to some extent in all forage crops investigated.

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