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 The CGI121 gene from Saccharomyces cerevisiae demonstrates genetic linkage to increased lag time under enological conditions

2020 ◽  
Author(s):  
Runze Li ◽  
Rebecca C. Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Genetic Linkage ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Phase Duration ◽  
Fermentation Kinetics ◽  
Lag Times ◽  
The Impact

Abstract Background In winemaking, it is standard practice to ferment white wines at low temperatures (10–18 ºC). However, low temperatures increase the fermentation duration and risk of problem ferments, which can lead to significant costs. The length of the lag period at fermentation initiation is one parameter that is heavily impacted by low temperatures. Therefore, the identification of Saccharomyces cerevisiae genes with an impact on fermentation kinetics, such as lag time, is of interest for winemaking. Results We selected a set of 28 S. cerevisiae BY4743 single deletants based on a prior list of candidate open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII influencing the duration of fermentative lag time by bulk segregant analysis. Five out of 28 BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag phase duration compared to BY4743 in synthetic grape medium (SGM) at 15 ºC, over 72 h. Fermentation at 12.5 ºC for 528 h, to show a greater resolution of the lag times, identified the inability of BY4743 Δapt1 to initiate fermentation and confirmed the significantly longer lag times of the BY4743 Δcgi121, Δrps17a, and Δvma21 deletants. The 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 ºC in SGM. Lag time measurements confirmed genetic linkage of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, to fermentative lag phase. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide suggesting that codon bias or positional effects might be responsible for the impact of this gene on lag phase duration. Conclusion This research demonstrates a new role of CGI121 in fermentative lag time in S. cerevisiae during fermentation and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast, such as fermentation kinetics.

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.

Operation of a Porous Membrane Photobioreactor

2016 ◽  
Author(s):  
Gary A. Anderson ◽  
Sarmila Katuwal ◽  
Anil Kommareddy ◽  
Stephen Gent
Keyword(s):  
Carbon Dioxide ◽  
Flow Pattern ◽  
Growth Medium ◽  
Light Guide ◽  
Porous Membrane ◽  
Lag Phase ◽  
Growth Media ◽  
Wall Area ◽  
Reactor Volume ◽  
Light Guides

A unique photobioreactor (PBR) constructed with acrylic sheet was used to grow S. Leopoliensis in 3.36 litters of Scully’s growth media. The PBR width was 51mm with a 273mm length and a growth media depth of 271mm. One of the PBR unique features was that it used a plenum and a porous membrane to inject air enriched with carbon dioxide into the growth medium. The HDPE (high-density polyethylene sintered beads) porous membrane served as the barrier between the reactor volume and the mixing plenum of the PBR. The air bubbled up through the porous membrane into the reactor volume with the growth medium mixing the contents of the reactor volume and transfer oxygen and carbon dioxide between the growth media and the bubbles. The second unique feature of the PBR is that it incorporated light guides in the design. The light guides were acrylic rods 9.5mm in diameter and a length projecting into the reactor volume of 38.1mm. The guides did not touch the opposite PBR wall. The light guides were abraded with sand paper on the outer to enhance light transfer from the guide to the growth medium. There were eight rows of light guides on each of the two PBR walls that were 273mm in length. Each row consisted of eight light guides space 34.1mm apart and 17.1mm from the side (short) walls of the PBR. Light was provided by two LED panels with 384 LED lights on each panel. The light from the panels had a wavelength of 650nm. The Light guides protruded through the PBR wall and light from the LED panels entered the light guide ends or transferred through the wall directly into the PBR reactor volume. The light guide ends occupied approximately 16% of the PBR wall area lit by the LED panels. The PBR produced 7.1g per litter of algal biomass in a 14 day growth cycle which encompassed a 3 day lag phase. The light guides disrupted the bubble flow pattern not allowing an obvious riser and/or downcomer to develop in the reactor volume. The disrupted flow pattern enhanced mixing and gas transfer. The enhanced mixing rotated the algal cells from more to less areas of the reactor volume more often aiding photosynthesis in a manner similar to flashing lights.

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.

scholarly journals Lag times and invasion dynamics of established and emerging weeds: insights from herbarium records of Queensland, Australia

2021 ◽  
Author(s):  
Olusegun O. Osunkoya ◽  
Claire B. Lock ◽  
Kunjithapatham Dhileepan ◽  
Joshua C. Buru
Keyword(s):  
Introduced Species ◽  
Significant Proportion ◽  
Lag Time ◽  
Linear Increase ◽  
Plant Distribution ◽  
Lag Phase ◽  
Weed Species ◽  
Historical Factors ◽  
Lag Times ◽  
Invasion Waves

AbstractHerbarium records provide comprehensive information on plant distribution, offering opportunities to construct invasion curves of introduced species, estimate their rates and patterns of expansions in novel ranges, as well as identifying lag times and hence “sleeper weeds”, if any. Lag times especially have rarely been determined for many introduced species, including weeds in the State of Queensland, Australia as the trait is thought to be unpredictable and cannot be screened for. Using herbarium records (1850–2010), we generated various invasiveness indices, and developed simple invasion and standardised proportion curves of changes in distribution with time for ~ 100 established and emerging weed species of Queensland. Four major periods (decades) of increased weed spread (spikes) were identified: 1850s, 1900–1920, 1950–1960 and 2000–2010, especially for grasses and trees/shrubs. Many weeds with spikes in spread periods did so only 1–2 decadal times, except for a few species with higher spike frequencies > 6; the majority of these spikes occurred recently (1950–1990). A significant proportion (~ 60%) of Queensland’s weeds exhibit non-linear increase in spread with time, and hence have lag phases (mean: 45.9 years; range: 12–126 years); of these lag-phase species, 39% are “sleeper” weeds with > 50 years of lag time (mainly trees/shrubs and grasses). Twelve traits of invasiveness, including lag time and species-specific/historical factors were screened, of which frequency of invasion waves, spread rates and residence time were the main drivers of weeds’ distribution. The low predictive power of lag time on weed distribution suggests that retrospective analyses offer little hope for a robust generalisation to identify weeds of tomorrow.

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 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 The implications of lag times between nitrate leaching losses and riverine loads for water quality policy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. W. McDowell ◽  
Z. P. Simpson ◽  
A. G. Ausseil ◽  
Z. Etheridge ◽  
R. Law
Keyword(s):  
Water Quality ◽  
Mean Transit Time ◽  
Lag Time ◽  
Practice Change ◽  
N Leaching ◽  
N Losses ◽  
Leaching Losses ◽  
Nitrate N ◽  
The Mean ◽  
Lag Times

AbstractUnderstanding the lag time between land management and impacts on riverine nitrate–nitrogen (N) loads is critical to understand when action to mitigate nitrate–N leaching losses from the soil profile may start improving water quality. These lags occur due to leaching of nitrate–N through the subsurface (soil and groundwater). Actions to mitigate nitrate–N losses have been mandated in New Zealand policy to start showing improvements in water quality within five years. We estimated annual rates of nitrate–N leaching and annual nitrate–N loads for 77 river catchments from 1990 to 2018. Lag times between these losses and riverine loads were determined for 34 catchments but could not be determined in other catchments because they exhibited little change in nitrate–N leaching losses or loads. Lag times varied from 1 to 12 years according to factors like catchment size (Strahler stream order and altitude) and slope. For eight catchments where additional isotope and modelling data were available, the mean transit time for surface water at baseflow to pass through the catchment was on average 2.1 years less than, and never greater than, the mean lag time for nitrate–N, inferring our lag time estimates were robust. The median lag time for nitrate–N across the 34 catchments was 4.5 years, meaning that nearly half of these catchments wouldn’t exhibit decreases in nitrate–N because of practice change within the five years outlined in policy.

Inhibition of Aspergillus spp. and Penicillium spp. by Fatty Acids and Their Monoglycerides

2007 ◽  
Vol 70 (5) ◽  
pp. 1206-1212 ◽  
Author(s):  
CLELIA ALTIERI ◽  
DANIELA CARDILLO ◽  
ANTONIO BEVILACQUA ◽  
MILENA SINIGAGLIA
Keyword(s):  
Fatty Acids ◽  
Fungal Growth ◽  
Lag Time ◽  
Mold Growth ◽  
Penicillium Species ◽  
Colony Diameter ◽  
Gompertz Equation ◽  
Lag Times ◽  
Penicillium Spp ◽  
Palmitic Acids

The antifungal activity of three fatty acids (lauric, myristic, and palmitic acids) and their monoglycerides (monolaurin, monomyristic acid, and palmitin, respectively) against Aspergillus and Penicillium species in a model system was investigated. Data were modeled through a reparameterized Gompertz equation. The maximum colony diameter attained within the experimental time (30 days), the maximal radial growth rate, the lag time (i.e., the number of days before the beginning of radial fungal growth), and the minimum detection time (MDT; the number of days needed to attain 1 cm colony diameter) were evaluated. Fatty acids and their monoglycerides inhibited mold growth by increasing MDT and lag times. The effectiveness of the active compounds seemed to be strain and genus dependent. Palmitic acid was the most effective chemical against aspergilli, whereas penicilli were strongly inhibited by myristic acid. Aspergilli also were more susceptible to fatty acids than were penicilli, as indicated by the longer MDT.

Sign in / Sign up

Export Citation Format

Share Document