scholarly journals Contrasting Effects of Heat Treatment and Incubation Temperature on Germination and Outgrowth of Individual Spores of Nonproteolytic Clostridium botulinum Bacteria

2009 ◽  
Vol 75 (9) ◽  
pp. 2712-2719 ◽  
Author(s):  
Sandra C. Stringer ◽  
Martin D. Webb ◽  
Michael W. Peck
Keyword(s):  
Heat Treatment ◽  
Clostridium Botulinum ◽  
Incubation Temperature ◽  
Lag Time ◽  
Growth Conditions ◽  
Lag Phase ◽  
The Times ◽  
Incubation Temperatures ◽  
Kinetics Of ◽  
Historical Treatment

ABSTRACT In this study, we determined the effects of incubation temperature and prior heat treatment on the lag-phase kinetics of individual spores of nonproteolytic Clostridium botulinum Eklund 17B. The times to germination (t germ), one mature cell (t C1), and two mature cells (t C2) were measured for individual unheated spores incubated at 8, 10, 15, or 22°C and used to calculate the t germ, the outgrowth time (t C1 − t germ), and the first doubling time (t C2 − t C1). Measurements were also made at 22°C of spores that had previously been heated at 80°C for 20 s. For unheated spores, outgrowth made a greater contribution to the duration and variability of the lag phase than germination. Decreasing incubation temperature affected germination less than outgrowth; thus, the proportion of lag associated with germination was less at lower incubation temperatures. Heat treatment at 80°C for 20 s increased the median germination time of surviving spores 16-fold and greatly increased the variability of spore germination times. The shape of the lag-time (t C1) and outgrowth (t C1 − t germ) distributions were the same for unheated spores, but heat treatment altered the shape of the lag-time distribution, so it was no longer homogeneous with the outgrowth distribution. Although heat treatment mainly extended germination, there is also evidence of damage to systems required for outgrowth. However, this damage was quickly repaired and was not evident by the time the cells started to double. The results presented here combined with previous findings show that the stage of lag most affected, and the extent of any effect in terms of duration or variability, differs with both historical treatment and the growth conditions.

scholarly journals Historical and Contemporary NaCl Concentrations Affect the Duration and Distribution of Lag Times from Individual Spores of Nonproteolytic Clostridium botulinum

2007 ◽  
Vol 73 (7) ◽  
pp. 2118-2127 ◽  
Author(s):  
Martin D. Webb ◽  
Carmen Pin ◽  
Michael W. Peck ◽  
Sandra C. Stringer
Keyword(s):  
Growth Medium ◽  
Clostridium Botulinum ◽  
Lag Time ◽  
Lag Phase ◽  
Growth Media ◽  
Sporulation Medium ◽  
Mature Cell ◽  
Inhibitory Effects ◽  
Subsequent Growth ◽  
Lag Times

ABSTRACT In this study we determined the effect of NaCl concentration during sporulation (0 or 3.0% [wt/vol] added NaCl) and subsequent growth (0 or 2.0% [wt/vol] added NaCl) on the distributions of times associated with various stages of the lag phase of individual spores of nonproteolytic Clostridium botulinum strain Eklund 17B. The effects of NaCl on the probability of germination and the probability of subsequent growth were also determined. Spore populations exhibited considerable heterogeneity at all stages of lag phase for each condition tested. Germination time did not correlate strongly with the times for later stages in the lag phase, such as outgrowth and doubling time. Addition of NaCl to either the sporulation or growth media increased the mean times for, and variability of, all the measured stages of the lag phase (germination, emergence, time to one mature cell, and time to first doubling). There was a synergistic interaction between the inhibitory effects of NaCl in the sporulation medium and the inhibitory effects of NaCl in the subsequent growth medium on the total lag time and each of its stages. Addition of NaCl to either the sporulation medium or the growth medium reduced both the probability of germination and the probability of a germinated spore developing into a mature cell, but the interaction was not synergistic. Spores formed in medium with added NaCl were not better adapted to subsequent growth in suboptimal osmotic conditions than spores formed in medium with no added NaCl were. Knowledge of the distribution of lag times for individual spores and quantification of the biovariability within lag time distributions may provide insight into the underlying mechanisms and can be used to improve predictions of growth in food and to refine risk assessments.

scholarly journals A Predictive Model That Describes the Effect of Prolonged Heating at 70 to 90°C and Subsequent Incubation at Refrigeration Temperatures on Growth from Spores and Toxigenesis by Nonproteolytic Clostridium botulinum in the Presence of Lysozyme

1999 ◽  
Vol 65 (8) ◽  
pp. 3449-3457 ◽  
Author(s):  
Pablo S. Fernández ◽  
Michael W. Peck
Keyword(s):  
Heat Treatment ◽  
Predictive Model ◽  
Clostridium Botulinum ◽  
Incubation Temperature ◽  
Storage Temperature ◽  
Treatment Guidelines ◽  
Heating Temperature ◽  
Toxin Production ◽  
Heat Treatments ◽  
Prolonged Heating

ABSTRACT Refrigerated processed foods of extended durability such as cook-chill and sous-vide foods rely on a minimal heat treatment at 70 to 95°C and then storage at a refrigeration temperature for safety and preservation. These foods are not sterile and are intended to have an extended shelf life, often up to 42 days. The principal microbiological hazard in foods of this type is growth of and toxin production by nonproteolytic Clostridium botulinum. Lysozyme has been shown to increase the measured heat resistance of nonproteolytic C. botulinum spores. However, the heat treatment guidelines for prevention of risk of botulism in these products have not taken into consideration the effect of lysozyme, which can be present in many foods. In order to assess the botulism hazard, the effect of heat treatments at 70, 75, 80, 85, and 90°C combined with refrigerated storage for up to 90 days on growth from 106 spores of nonproteolytic C. botulinum(types B, E, and F) in an anaerobic meat medium containing 2,400 U of lysozyme per ml (50 μg per ml) was studied. Provided that the storage temperature was no higher than 8°C, the following heat treatments each prevented growth and toxin production during 90 days; 70°C for ≥2,545 min, 75°C for ≥463 min, 80°C for ≥230 min, 85°C for ≥84 min, and 90°C for ≥33.5 min. A factorial experimental design allowed development of a predictive model that described the incubation time required before the first sample showed growth, as a function of heating temperature (70 to 90°C), period of heat treatment (up to 2,545 min), and incubation temperature (5 to 25°C). Predictions from the model provided a valid description of the data used to generate the model and agreed with observations made previously.

Germination of Spores of Clostridium botulinum Type G

1988 ◽  
Vol 51 (1) ◽  
pp. 37-38 ◽  
Author(s):  
KOICHI TAKESHI ◽  
YOSHIAKI ANDO ◽  
KEIJI OGUMA
Keyword(s):  
Incubation Time ◽  
Clostridium Botulinum ◽  
Incubation Temperature ◽  
Germination Medium ◽  
Botulinum Type ◽  
Heat Activation ◽  
Incubation Temperatures

Germination of spores of Clostridium botulinum type G under various conditions of heat activation, incubation temperature and minimum nutrition was studied. The spores were optimally germinated in a mixture of L-cysteine + L-lactacte + bicarbonate. The rate and extent of germination were greatly increased when unheated spores were heat-activated at 75°C for 10 min before exposure to the germination medium. Maximum germination was obtained at incubation temperatures of 37 to 45°C within 1 h. However, germination occurred substantially even at 4°C if the incubation time was extended to 48 h.

scholarly journals Heterogeneity of Times Required for Germination and Outgrowth from Single Spores of Nonproteolytic Clostridium botulinum

2005 ◽  
Vol 71 (9) ◽  
pp. 4998-5003 ◽  
Author(s):  
Sandra C. Stringer ◽  
Martin D. Webb ◽  
Susan M. George ◽  
Carmen Pin ◽  
Michael W. Peck
Keyword(s):  
Clostridium Botulinum ◽  
Phase Contrast ◽  
Total Duration ◽  
Substantial Contribution ◽  
Lag Phase ◽  
Considerable Variability ◽  
Subsequent Growth ◽  
Contrast Microscopy ◽  
Dividing Cells ◽  
The Times

ABSTRACT Knowledge of the distribution of growth times from individual spores and quantification of this biovariability are important if predictions of growth in food are to be improved, particularly when, as for Clostridium botulinum, growth is likely to initiate from low numbers of spores. In this study we made a novel attempt to determine the distributions of times associated with the various stages of germination and subsequent growth from spores and the relationships between these stages. The time to germination (t germ), time to emergence (t emerg), and times to reach the lengths of one (t C1) and two (t C2) mature cells were quantified for individual spores of nonproteolytic C. botulinum Eklund 17B using phase-contrast microscopy and image analysis. The times to detection for wells inoculated with individual spores were recorded using a Bioscreen C automated turbidity reader and were compatible with the data obtained microscopically. The distributions of times to events during germination and subsequent growth showed considerable variability, and all stages contributed to the overall variability in the lag time. The times for germination (t germ), emergence (t emerg − t germ), cell maturation (t C1 − t emerg), and doubling (t C2 − t C1) were not found to be correlated. Consequently, it was not possible to predict the total duration of the lag phase from information for just one of the stages, such as germination. As the variability in postgermination stages is relatively large, the first spore to germinate will not necessarily be the first spore to produce actively dividing cells and start neurotoxin production. This information can make a substantial contribution to improved predictive modeling and better quantitative microbiological risk assessment.

Growth and Germination of Proteolytic Clostridium botulinum in Vegetable-Based Media

2003 ◽  
Vol 66 (5) ◽  
pp. 833-839 ◽  
Author(s):  
AGNÈS BRACONNIER ◽  
VÉRONIQUE BROUSSOLLE ◽  
CLAIRE DARGAIGNARATZ ◽  
CHRISTOPHE NGUYEN-THE ◽  
FRÉDÉRIC CARLIN
Keyword(s):  
Growth Rate ◽  
Clostridium Botulinum ◽  
Sodium Lactate ◽  
Nutrient Broth ◽  
Cell Populations ◽  
Lag Phase ◽  
Redox Potentials ◽  
Spore Count ◽  
Lag Times ◽  
The Times

The growth of proteolytic Clostridium botulinum from spore inocula and changes in spore counts in mushroom, broccoli, and potato purées were monitored. Four strains of proteolytic C. botulinum types A and B were inoculated separately at approximately 104 spores per ml in nutrient broth and vegetable purées incubated at 15, 20, and 30°C for up to 52 days. The times for the cell populations to increase 1,000-fold (T1,000) in the tested vegetables (1 to 5 days at 30°C, 3 to 16 days at 20°C, 7 to >52 days at 15°C) were similar to those for meat or fish. Only temperature significantly influenced growth rate. In contrast, the lag phase depended on the strains and media tested, in addition to temperature. Lag times and T1,000s for proteolytic C. botulinum were longer for potato and broccoli purées than for mushroom purée. These differences were not related to different pHs or redox potentials. The germination level, evaluated as the decrease in the spore count, was low. The addition of a germinant mixture (L-cysteine, L-alanine, and sodium lactate) to some strains inoculated in vegetable purées resulted in an increase in germination, suggesting a lack of germination-triggering agents in the vegetable purées.

Development and Evaluation of Floating Pulsatile Drug Delivery System Using Meloxicam

2017 ◽  
Vol 7 (04) ◽  
Author(s):  
ShirishaG. Suddala ◽  
S. K. Sahoo ◽  
M. R. Yamsani
Keyword(s):  
Rheumatoid Arthritis ◽  
Drug Delivery ◽  
Drug Release ◽  
Drug Delivery System ◽  
Delivery System ◽  
Lag Time ◽  
Oral Dosage ◽  
Lag Phase ◽  
Pulsatile Drug Delivery

Objective: The objective of this research work was to develop and evaluate the floating– pulsatile drug delivery system (FPDDS) of meloxicam intended for Chrono pharmacotherapy of rheumatoid arthritis. Methods: The system consisting of drug containing core, coated with hydrophilic erodible polymer, which is responsible for a lag phase for pulsatile release, top cover buoyant layer was prepared with HPMC K4M and sodium bicarbonate, provides buoyancy to increase retention of the oral dosage form in the stomach. Meloxicam is a COX-2 inhibitor used to treat joint diseases such as osteoarthritis and rheumatoid arthritis. For rheumatoid arthritis Chrono pharmacotherapy has been recommended to ensure that the highest blood levels of the drug coincide with peak pain and stiffness. Result and discussion: The prepared tablets were characterized and found to exhibit satisfactory physico-chemical characteristics. Hence, the main objective of present work is to formulate FPDDS of meloxicam in order to achieve drug release after pre-determined lag phase. Developed formulations were evaluated for in vitro drug release studies, water uptake and erosion studies, floating behaviour and in vivo radiology studies. Results showed that a certain lag time before drug release which was due to the erosion of the hydrophilic erodible polymer. The lag time clearly depends on the type and amount of hydrophilic polymer which was applied on the inner cores. Floating time and floating lag time was controlled by quantity and composition of buoyant layer. In vivo radiology studies point out the capability of the system of longer residence time of the tablets in the gastric region and releasing the drug after a programmed lag time. Conclusion: The optimized formulation of the developed system provided a lag phase while showing the gastroretension followed by pulsatile drug release that would be beneficial for chronotherapy of rheumatoid arthritis and osteoarthritis.

scholarly journals Characterisation of Lactobacillus rhamnosus VT1 and its effect on the growth of Candida maltosa YP1

2008 ◽  
Vol 25 (No. 5) ◽  
pp. 272-282 ◽  
Author(s):  
D. Liptáková ◽  
Ľ. Valík ◽  
A. Lauková ◽  
V. Strompfová
Keyword(s):  
Growth Rate ◽  
Incubation Temperature ◽  
Lactobacillus Rhamnosus ◽  
Microbial Interactions ◽  
Lag Phase ◽  
Regression Equations ◽  
Candida Maltosa ◽  
Food Protection ◽  
Spoilage Yeast ◽  
Standard Response

The combined effect of initial amount of 18 h <i>L. rhamnosus</i> VT1 inoculum and incubation temperature on the growth of <i>Candida maltosa</i> YP1, an oxidative food spoilage yeast strain, was primarily modelled and studied by standard response surface methodology. This study resulted in the following linear regression equations characterising lag time and growth rate of <i>C. maltosa</i> YP1 in milk in competition with the potentially protective lactobacillus strain. Lag-phase of <i>C. maltosa</i> was strongly influenced by the amount of lactobacillus inoculum (<i>V</i><sub>0</sub>) and incubation temperature (1/<i>T</i>). The synergic effect of both these factors was also evident as results from the equation lag = –33.50 + 186.38 × <i>V</i><sub>0</sub> × 1/<i>T</i> + 512.27 × 1/<i>T</i> – 5.511 × <i>V</i><sub>0</sub> (<i>R</i><sup>2</sup><sub>(λ)</sub> = 0.849). The growth rate was sufficiently described by the linear relation: <i>Gr</i><sub>Cm</sub> = –0.00046 + 0.0033 × <i>T</i> – 0.0016 × <i>V</i><sub>0 (<i>R</i><sup>2</sup><sub>(Gr)</sub> = 0.847). On the basis of these equations, the mutual microbial interactions and the potential application of the lactobacillus strains to food protection are discussed.

scholarly journals Reciprocal hemizygosity analysis reveals that the Saccharomyces cerevisiae CGI121 gene affects lag time duration in synthetic grape must

2021 ◽  
Author(s):  
Runze Li ◽  
Rebecca C Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Time Duration ◽  
Phase Duration ◽  
Grape Must ◽  
The Impact ◽  
Reciprocal Hemizygosity Analysis

Abstract It is standard practice to ferment white wines at low temperatures (10-18 °C). However, low temperatures increase fermentation duration and risk of problem ferments, leading to significant costs. The lag duration at fermentation initiation is heavily impacted by temperature; therefore, identification of Saccharomyces cerevisiae genes influencing fermentation kinetics is of interest for winemaking. We selected 28 S. cerevisiae BY4743 single deletants, from a prior list of open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII, influencing the duration of fermentative lag time. Five BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag duration compared to BY4743 in synthetic grape must (SGM) at 15 °C, over 72 h. Fermentation at 12.5 °C for 528 h confirmed the longer lag times of BY4743 Δcgi121, Δrps17a, and Δvma21. These three candidate ORFs were deleted in S. cerevisiae RM11-1a and S288C to perform single reciprocal hemizygosity analysis (RHA). RHA hybrids and single deletants of RM11-1a and S288C were fermented at 12.5 °C in SGM and lag time measurements confirmed that the S288C allele of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, increased fermentative lag phase duration. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide, suggesting that intron splicing, codon bias, or positional effects might be responsible for the impact on lag phase duration. This research demonstrates a new role of CGI121 and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast.

scholarly journals Kinetics of tau aggregation reveals patient specific tau characteristics among Alzheimer's cases

2021 ◽  
Author(s):  
Tarun V Kamath ◽  
Naomi Klickstein ◽  
Caitlin Commins ◽  
Analiese R Fernandes ◽  
Derek H Oakley ◽  
...  
Keyword(s):  
Growth Phase ◽  
Tau Proteins ◽  
Patient Specific ◽  
Lag Phase ◽  
Plateau Phase ◽  
Kinetic Assay ◽  
Cellular Processes ◽  
Morphological Differences ◽  
Tau Aggregation ◽  
Kinetics Of

Abstract The accumulation of tau aggregates throughout the human brain is the hallmark of a number of neurodegenerative conditions classified as tauopathies. Increasing evidence shows that tau aggregation occurs in a “prion-like” manner, in which a small amount of misfolded tau protein can induce other, naïve tau proteins to aggregate. Tau aggregates have been found to differ structurally among different tauopathies. Recently, however, we have suggested that tau oligomeric species may differ biochemically among individual patients with sporadic Alzheimer disease, and have also showed that the bioactivity of the tau species, measured using a cell-based bioassay, also varied among individuals. Here, we adopted a live-cell imaging approach to the standard cell-based bioassay to explore further whether the kinetics of aggregation also differentiated these patients. We found that aggregation can be observed to follow a consistent pattern in all cases, with a lag phase, a growth phase, and a plateau phase, which each provide quantitative parameters by which we characterize aggregation kinetics. The length of the lag phase and magnitude of the plateau phase are both dependent upon the concentration of seeding-competent tau, the relative enrichment of which differs among patients. The slope of the growth phase correlates with morphological differences in the tau aggregates, which may be reflective of underlying structural differences. This kinetic assay confirms and refines the concept of heterogeneity in the characteristics of tau proteopathic seeds among individuals with Alzheimer’s disease and is a method by which future studies may characterize longitudinal changes in tau aggregation and the cellular processes which may influence these changes.

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