Controls on Domoic Acid Production by the Diatom Nitzschia pungens f. multiseries in Culture: Nutrients and Irradïance

1991 ◽  
Vol 48 (7) ◽  
pp. 1136-1144 ◽  
Author(s):  
S. S. Bates ◽  
A. S. W. de Freitas ◽  
J. E. Milley ◽  
R. Pocklington ◽  
M. A. Quilliam ◽  
...  
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Domoic Acid ◽  
Culture Medium ◽  
Dark Period ◽  
Growth Conditions ◽  
Dark Cycle ◽  
Division Rate ◽  
Nitzschia Pungens

Nitzschia pungens f. multiseries (clone NPARL) was grown in nonaxenic batch culture under a range of growth conditions. Domoic acid (DA) was not detected during exponential growth, but production promptly started at a rate of approximately 1 pg DA∙cell−1∙d−1 at the onset of the stationary phase, in this case induced by silicate limitation. Cellular DA reached a maximum of 7 pg∙cell−1; thereafter, DA production continued at the same rate, with cellular levels remaining relatively constant due to concurrent release of DA into the culture medium. DA production ceased in the absence of nitrogen during the stationary phase, but resumed when nitrate was added back to the medium. Low irradiance slowed the division rate and consequently delayed the attainment of the stationary phase, but DA production rates were comparable with the control once stationary phase was reached. Cells during the dark period of a light–dark cycle, or placed into darkness, or in the presence of the photosynthetic inhibitor DCMU promptly ceased DA production. We conclude that at least three conditions are required for DA production by clone NPARL: cessation of cell division, availability of nitrogen during the stationary phase, and the presence of light. Growth in medium f/2 fulfils these requirements.

Production of Domoic Acid, a Neurotoxic Amino Acid, by an Axenic Culture of the Marine Diatom Nitzschia pungens f. multiseries Hasle

1992 ◽  
Vol 49 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Donald J. Douglas ◽  
Stephen S. Bates
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Domoic Acid ◽  
Stationary Phases ◽  
Axenic Culture ◽  
Marine Diatom ◽  
Epifluorescence Microscopy ◽  
Division Rate ◽  
Growth Production ◽  
Nitzschia Pungens

A microbially contaminated culture of Nitzschia pungens f. multiseries (clone TKA-2) was treated with gentamicin followed by a combination of penicillin and streptomycin. An axenic culture was successfully isolated as evidenced by sterility tests using four different nutrient enrichment media and examination by epifluorescence microscopy. The isolate had a specific division rate (0.65∙d−1) comparable with that reported for nonaxenic cultures. The axenic culture produced domoic acid (DA) during the lag and stationary phases, when cell division rates were low or zero, but not during exponential growth. Production of DA resumed within 1 d after cell division ceased and reached 0.5 pg DA∙cell−1∙d−1 2–3 d after the onset of the stationary phase. A maximum concentration of 2.0 pg DA∙cell−1 was reached after 6 d in stationary phase. Our results provide the first evidence that N. pungens f. multiseries produces DA in the absence of other microorganisms.

ABNORMAL GROWTH INDUCED BY PENICILLIN IN A STRAIN OF ALCALIGENES FECALIS

1958 ◽  
Vol 4 (2) ◽  
pp. 165-177 ◽  
Author(s):  
K. G. Lark
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Exponential Growth ◽  
Division Rate ◽  
Abnormal Growth ◽  
Globular Form ◽  
Kinetics Of

The effect of penicillin on strain LB of Alcaligenes fccalis has been studied. In tryptone, 50 units/ml. of penicillin transforms the bacillary form of this organism into a protoplast-like structure (globular form) which is capable of exponential growth and division. The division rate of this globular form is about one-half that of the bacillary form. Removal of penicillin results in the reversion of the globular to the bacillary form. Multiplication of the globular form has been found to depend on the presence of some principle present in tryptone not required for bacillary growth in the absence of penicillin. The kinetics of the transformation and reversion process have been studied, leading to the hypothesis that penicillin affects some component: within the cell, this component being concerned with cell division and the elaboration of the cell wall.

scholarly journals The LysR-Type Transcriptional Regulator YofA Controls Cell Division through the Regulation of Expression of ftsW in Bacillus subtilis

2007 ◽  
Vol 189 (15) ◽  
pp. 5642-5651 ◽  
Author(s):  
Zuolei Lu ◽  
Michio Takeuchi ◽  
Tsutomu Sato
Keyword(s):  
Bacillus Subtilis ◽  
Cell Division ◽  
Stationary Phase ◽  
Cell Density ◽  
Exponential Growth ◽  
Insertion Mutant ◽  
Regulation Of Expression ◽  
Dependent Growth ◽  
Stationary Phase Analysis ◽  
Final Round

ABSTRACT We have carried out a functional analysis of LysR family transcriptional regulators in Bacillus subtilis. The cell density of cultures of a yofA insertion mutant declined sharply after the end of exponential growth, as measured by optical density at 600 nm. Complementation in trans and analysis of isopropyl-β-d-thiogalactopyranoside (IPTG)-dependent growth of an inducible yofA strain confirmed that YofA contributes to the cell density of a culture after the end of exponential growth. Microscopic observation suggested that cell division is inhibited or delayed in the yofA mutant during entry into stationary phase. Analysis of the transcription of cell division genes revealed that the expression of ftsW is inhibited in yofA mutants, and overexpression of yofA, driven by a multiple-copy plasmid, enhances the induction of ftsW expression. These results suggest that YofA is required for the final round of cell division before entry into stationary phase and that YofA positively regulates ftsW expression. The defects caused by mutation of yofA were suppressed in strains carrying P spac -ftsW in the presence of IPTG. Furthermore, maximal expression of yofA was observed at the onset of stationary phase, which coincided with the maximal ftsW expression. Our data indicate that YofA is involved in cell division through positive regulation of the expression of ftsW in B. subtilis.

Effects of Ammonium and Nitrate on Growth and Domoic Acid Production by Nitzschia pungens in Batch Culture

1993 ◽  
Vol 50 (6) ◽  
pp. 1248-1254 ◽  
Author(s):  
Stephen S. Bates ◽  
Jean Worms ◽  
John C. Smith
Keyword(s):  
Stationary Phase ◽  
Batch Culture ◽  
Domoic Acid ◽  
Skeletonema Costatum ◽  
Cell Yield ◽  
Ammonia Toxicity ◽  
Lag Phase ◽  
Enhanced Production ◽  
Nitrogen Concentrations ◽  
Nitzschia Pungens

Four clones of Nitzschia pungens f. multiseries (toxin-producing form) and two of N. pungens f. pungens (nontoxic) were grown in batch culture at initial nitrogen concentrations of 55, 110, 220, 440, and 880 μM in the form of either nitrate or ammonium. As expected, only N. pungens f. multiseries clones produced the neurotoxin, domoic acid (DA). Ammonium at 880 μM prevented the growth of all N. pungens clones but not of Skeletonema costatum, although division rate was reduced. At 440 μM, ammonium lowered the cell yield obtained during the stationary phase, inhibited photosynthesis, and caused a lag phase during which DA was produced (by f. multiseries). At 220 and 440 μM ammonium, in contrast with the same concentrations of nitrate, stationary phase cellular DA production was enhanced by two- to fourfold. At 110 and 55 μM nitrogen, cell yield and DA production were equivalent for nitrate and ammonium but less DA was produced relative to the higher nitrogen concentrations, possibly due to nitrogen depletion. Enhanced production of DA at elevated ammonium concentrations may be a response to ammonia toxicity. This could be a useful tool for studying mechanisms of DA production and for maximizing the yield of this valuable toxin in large-scale cultures.

Domoic Acid—A Neurotoxic Amino Acid Produced by the Marine Diatom Nitzschia pungens in Culture

1988 ◽  
Vol 45 (12) ◽  
pp. 2076-2079 ◽  
Author(s):  
D. V. Subba Rao ◽  
M. A. Quilliam ◽  
R. Pocklington
Keyword(s):  
Amino Acid ◽  
Chemical Analysis ◽  
River Water ◽  
Prince Edward Island ◽  
Domoic Acid ◽  
Culture Medium ◽  
Marine Diatom ◽  
Eastern Canada ◽  
Blue Mussels ◽  
Nitzschia Pungens

During late 1987, an outbreak of poisoning resulting from the ingestion of cultivated blue mussels (Mytilus edulis) from a localized area in eastern Canada (Cardigan Bay, Prince Edward Island) was associated with massive blooms of Nitzschia pungens, a widely distributed diatom not previously known to produce toxins; human fatalities resulted. Here we provide proof that the causative agent, domoic acid, is indeed produced by this diatom. Although no domoic acid could be detected (<2 ng∙mL−1) in culture medium (FE) prepared from Cardigan River water, it was found in cultures of Nitzschia pungens grown in this medium at concentrations ranging from 0.03 to 0.8 pg∙cell−1 in various separate cultures harvested for chemical analysis 7–68 d after inoculation.

Morphology of the Toxin-Producing Diatom Nitzschia pungens Grunow forma multiseries Hasle

1992 ◽  
Vol 49 (2) ◽  
pp. 303-311 ◽  
Author(s):  
Daniel J. MacPhee ◽  
Louis A. Hanic ◽  
Dianne L. Friesen ◽  
David E. Sims
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Cell Motility ◽  
Prince Edward Island ◽  
Domoic Acid ◽  
Light And Electron Microscopy ◽  
Cell Ultrastructure ◽  
Field Samples ◽  
Toxic Blooms ◽  
Nitzschia Pungens

The toxin-producing diatom Nitzschia pungens Grunow forma multiseries Hasle from three toxic blooms in two Prince Edward Island estuaries, spanning 1987–89, was studied using light and electron microscopy. Cell ultrastructure of N. pungens is, in general, similar to that of other species of Nitzschia and other diatoms. Important features include prominent peripheral, polarized nucleoli (numbering one or two) and imperforate poroids, present on inner valves and girdle bands. Cell division is usually synchronous for all cells in a filament with respect to polarity and time. Postdivisional elongation of the filament appears to involve a "slide-by" process whereby sibling cells slide by each other along their opposed valve faces and then stop, becoming fused by their overlapping tips. The raphe is probably involved in this, as well as in filament and cell motility. Observations of particle motion along the cell raphe suggest the existence of a motility apparatus such as microcilia which would facilitate locomotion, intercellular coordination, and the postdivisional slide-by process. No bacteria or other organisms were observed associated with field samples of toxic N. pungens f. multiseries. This supports a view that domoic acid production is autonomous.

Effect of various growth conditions on spore formation and bacillomycin L production in Bacillus subtilis

1986 ◽  
Vol 32 (3) ◽  
pp. 254-258 ◽  
Author(s):  
Catherine Chevanet ◽  
Françoise Besson ◽  
Georges Michel
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Culture Medium ◽  
Diethyl Malonate ◽  
Growth Conditions ◽  
Spore Formation ◽  
Bacterial Cells ◽  
Antibiotic Synthesis ◽  
Bacillomycin L ◽  
Specific Inhibitors

Bacillomycin L is produced by Bacillus subtilis NCIB 8872 in the stationary phase; it is excreted into the culture medium, without prior accumulation in the bacterial cells. The production of bacillomycin L is largely dependent on the composition of the culture medium. The action of specific inhibitors of sporulation, netropsin and diethyl malonate, on antibiotic synthesis is dependent on the composition of the culture medium. Although they occurred at the same time, there appears to be no direct correlation between sporulation and antibiotic synthesis.

scholarly journals Adaptive reversion of a frameshift mutation in Escherichia coli.

Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 695-701 ◽  
Author(s):  
J Cairns ◽  
P L Foster
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Frameshift Mutation ◽  
Rare Event ◽  
Lacz Fusion ◽  
Mutation Rates ◽  
Classical Studies ◽  
Selective Forces

Abstract Mutation rates are generally thought not to be influenced by selective forces. This doctrine rests on the results of certain classical studies of the mutations that make bacteria resistant to phages and antibiotics. We have studied a strain of Escherichia coli which constitutively expresses a lacI-lacZ fusion containing a frameshift mutation that renders it Lac-. Reversion to Lac+ is a rare event during exponential growth but occurs in stationary cultures when lactose is the only source of energy. No revertants accumulate in the absence of lactose, or in the presence of lactose if there is another, unfulfilled requirement for growth. The mechanism for such mutation in stationary phase is not known, but it requires some function of RecA which is apparently not required for mutation during exponential growth.

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2504-2514 ◽  
Author(s):  
Mário H. Queiroz ◽  
Cristina Madrid ◽  
Sònia Paytubi ◽  
Carlos Balsalobre ◽  
Antonio Juárez
Keyword(s):  
Stationary Phase ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Integration Host Factor ◽  
Band Shift ◽  
Global Regulators ◽  
Serovar Typhimurium ◽  
Associated Proteins ◽  
Transcription Data

Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

scholarly journals Acinetobacter baylyi Starvation-Induced Genes Identified through Incubation in Long-Term Stationary Phase

2010 ◽  
Vol 76 (14) ◽  
pp. 4905-4908 ◽  
Author(s):  
C. Phoebe Lostroh ◽  
Bruce A. Voyles
Keyword(s):  
Gene Expression ◽  
Stationary Phase ◽  
Batch Culture ◽  
Exponential Growth ◽  
Hypothetical Proteins ◽  
Acinetobacter Baylyi ◽  
Metabolic Gene Expression ◽  
Induced Genes ◽  
Dna Maintenance

ABSTRACT Acinetobacter species encounter cycles of feast and famine in nature. We show that populations of A cinetobacter baylyi strain ADP1 remain dynamic for 6 weeks in batch culture. We created a library of lacZ reporters inserted into SalI sites in the genome and then isolated 30 genes with lacZ insertions whose expression was induced by starvation during long-term stationary phase compared with their expression during exponential growth. The genes encode metabolic, gene expression, DNA maintenance, envelope, and conserved hypothetical proteins.

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