scholarly journals Environmental Regulation of PndbA600, an Auto-Inducible Promoter for Two-Stage Industrial Biotechnology in Cyanobacteria

2021 ◽  
Vol 8 ◽  
Author(s):  
Mary Ann Madsen ◽  
Graham Hamilton ◽  
Pawel Herzyk ◽  
Anna Amtmann
Keyword(s):  
Stationary Phase ◽  
Environmental Regulation ◽  
Growth Phase ◽  
Rational Design ◽  
Growth Media ◽  
Industrial Biotechnology ◽  
N Availability ◽  
Factor X ◽  
Two Stage ◽  
Culture Density

Cyanobacteria are photosynthetic prokaryotes being developed as sustainable platforms that use renewable resources (light, water, and air) for diverse applications in energy, food, environment, and medicine. Despite the attractive promise that cyanobacteria offer to industrial biotechnology, slow growth rates pose a major challenge in processes which typically require large amounts of biomass and are often toxic to the cells. Two-stage cultivation strategies are an attractive solution to prevent any undesired growth inhibition by de-coupling biomass accumulation (stage I) and the industrial process (stage II). In cyanobacteria, two-stage strategies involve costly transfer methods between stages I and II, and little work has been focussed on using the distinct growth and stationary phases of batch cultures to autoregulate stage transition. In the present study, we identified and characterised a growth phase-specific promoter, which can serve as an auto-inducible switch to regulate two-stage bioprocesses in cyanobacteria. First, growth phase-specific genes were identified from a new RNAseq dataset comparing two growth phases and six nutrient conditions in Synechocystis sp. PCC 6803, including two new transcriptomes for low Mg and low K. A type II NADH dehydrogenase (ndbA) showed robust induction when the cultures transitioned from exponential to stationary phase growth. Behaviour of a 600-bp promoter sequence (PndbA600) was then characterised in detail following the expression of PndbA600:GFP in Synechococcus sp. PCC 7002. Culture density and growth media analyses showed that PndbA600 activation was not dependent on increases in culture density per se but on N availability and on another activating factor present in the spent media of stationary phase cultures (Factor X). PndbA600 deactivation was dependent on the changes in culture density and in either N availability or Factor X. Electron transport inhibition studies revealed a photosynthesis-specific enhancement of active PndbA600 levels. Our findings are summarised in a model describing the environmental regulation of PndbA600, which can now inform the rational design of two-stage industrial processes in cyanobacteria.

Effects of Additional Mg2+ on the Growth and Lipid Accumulation of Monoraphidium Sp. FXY-10 under Mixotrophic Conditions

2013 ◽  
Vol 860-863 ◽  
pp. 920-927
Author(s):  
Rao Qiong Che ◽  
Qiu Mei Wang ◽  
Li Huang ◽  
Peng Zhao ◽  
Xu Ya Yu
Keyword(s):  
Stationary Phase ◽  
Lipid Content ◽  
Growth Phase ◽  
Lipid Accumulation ◽  
Biomass Productivity ◽  
Stationary Growth Phase ◽  
Growth Media ◽  
Stationary Growth ◽  
The Media ◽  
Mixotrophic Conditions

The effects of additional Mg2+ on the growth and lipid accumulation of the microalgae Monoraphidium sp. FXY-10 under mixotrophic conditions were investigated. 100 μmol Mg2+ were added to the growth media during the stationary growth phase. Compared with the control (35.25%), the highest lipid content reached up to 37.13% biomass after Mg2+ was added to the media. Moreover, the higher lipid productivity of 79.83 mg L1 d1 and the biomass productivity of 214.65 mg L1 d1 were attained in the Mg2+-supplemented cultures, as compared with cultures without supplemented (72.95 mg L1 d1 and 179.28 mg L1 d1, respectively). The use of Mg2+ supplements were proven to stimulate cell regrowth, prolong the stationary phase, and promote lipid accumulation in Monoraphidium sp. FXY-10.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

scholarly journals Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

2008 ◽  
Vol 74 (15) ◽  
pp. 4847-4852 ◽  
Author(s):  
Anastasia Matthies ◽  
Thomas Clavel ◽  
Michael Gütschow ◽  
Wolfram Engst ◽  
Dirk Haller ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Enzyme Induction ◽  
Growth Phase ◽  
Anaerobic Bacterium ◽  
Stationary Growth Phase ◽  
Gut Bacteria ◽  
Soy Isoflavones ◽  
Strictly Anaerobic ◽  
Stationary Growth ◽  
Mouse Intestine

ABSTRACT The metabolism of isoflavones by gut bacteria plays a key role in the availability and bioactivation of these compounds in the intestine. Daidzein and genistein are the most common dietary soy isoflavones. While daidzein conversion yielding equol has been known for some time, the corresponding formation of 5-hydroxy-equol from genistein has not been reported previously. We isolated a strictly anaerobic bacterium (Mt1B8) from the mouse intestine which converted daidzein via dihydrodaidzein to equol as well as genistein via dihydrogenistein to 5-hydroxy-equol. Strain Mt1B8 was a gram-positive, rod-shaped bacterium identified as a member of the Coriobacteriaceae. Strain Mt1B8 also transformed dihydrodaidzein and dihydrogenistein to equol and 5-hydroxy-equol, respectively. The conversion of daidzein, genistein, dihydrodaidzein, and dihydrogenistein in the stationary growth phase depended on preincubation with the corresponding isoflavonoid, indicating enzyme induction. Moreover, dihydrogenistein was transformed even more rapidly in the stationary phase when strain Mt1B8 was grown on either genistein or daidzein. Growing the cells on daidzein also enabled conversion of genistein. This suggests that the same enzymes are involved in the conversion of the two isoflavones.

scholarly journals Function of the Pyruvate Oxidase-Lactate Oxidase Cascade in Interspecies Competition between Streptococcus oligofermentans and Streptococcus mutans

2012 ◽  
Vol 78 (7) ◽  
pp. 2120-2127 ◽  
Author(s):  
Lei Liu ◽  
Huichun Tong ◽  
Xiuzhu Dong
Keyword(s):  
Stationary Phase ◽  
Streptococcus Mutans ◽  
Growth Phase ◽  
Large Degree ◽  
Interspecies Interactions ◽  
Lactate Oxidase ◽  
Interspecies Competition ◽  
Pyruvate Oxidase ◽  
Content Type

ABSTRACTComplex interspecies interactions occur constantly between oral commensals and the opportunistic pathogenStreptococcus mutansin dental plaque. Previously, we showed that oral commensalStreptococcus oligofermentanspossesses multiple enzymes for H2O2production, especially lactate oxidase (Lox), allowing it to out-competeS. mutans. In this study, through extensive biochemical and genetic studies, we identified a pyruvate oxidase (pox) gene inS. oligofermentans. Apoxdeletion mutant completely lost Pox activity, while ectopically expressedpoxrestored activity. Pox was determined to produce most of the H2O2in the earlier growth phase and log phase, while Lox mainly contributed to H2O2production in stationary phase. Bothpoxandloxwere expressed throughout the growth phase, while expression of theloxgene increased by about 2.5-fold when cells entered stationary phase. Since lactate accumulation occurred to a large degree in stationary phase, the differential Pox- and Lox-generated H2O2can be attributed to differential gene expression and substrate availability. Interestingly, inactivation ofpoxcauses a dramatic reduction in H2O2production from lactate, suggesting a synergistic action of the two oxidases in converting lactate into H2O2. In anin vitrotwo-species biofilm experiment, thepoxmutant ofS. oligofermentansfailed to inhibitS. mutanseven thoughloxwas active. In summary,S. oligofermentansdevelops a Pox-Lox synergy strategy to maximize its H2O2formation so as to win the interspecies competition.

scholarly journals Modulation of mRNA Stability Participates in Stationary-Phase-Specific Expression of Ribosome Modulation Factor

2005 ◽  
Vol 187 (6) ◽  
pp. 1951-1958 ◽  
Author(s):  
Toshiko Aiso ◽  
Hideji Yoshida ◽  
Akira Wada ◽  
Reiko Ohki
Keyword(s):  
Stationary Phase ◽  
Growth Phase ◽  
Mrna Stability ◽  
De Novo ◽  
Fresh Medium ◽  
Specific Expression ◽  
Modulation Factor ◽  
Inactive Form ◽  
Regulation Of Growth ◽  
Ribosome Modulation Factor

ABSTRACT The expression of ribosome modulation factor (RMF) is induced during stationary phase in Escherichia coli. RMF participates in the dimerization of 70S ribosomes to form the 100S ribosome, which is the translationally inactive form of the ribosome. To elucidate the involvement of the control of mRNA stability in growth-phase-specific rmf expression, we investigated rmf mRNA stability in stationary-phase cells and cells inoculated into fresh medium. The rmf mRNA was found to have an extremely long half-life during stationary phase, whereas destabilization of this mRNA took place after the culture was inoculated into fresh medium. RMF and 100S ribosomes disappeared from cells 1 min after inoculation. In addition to control by ppGpp-dependent transcription, these results indicate that the modulation of rmf mRNA stability is also involved in the regulation of growth-phase-specific rmf expression. Unexpectedly, the postinoculation degradation of rmf mRNA was suppressed by the addition of rifampin, suggesting that de novo RNA synthesis is necessary for degradation. This degradation was also suppressed in both a poly(A) polymerase-deficient and an rne-131 mutant strain. We cloned and sequenced the 3′-proximal regions of rmf mRNAs and found that most of these 3′ ends terminated at the ρ-independent terminator with the addition of a one- to five-A oligo(A) tail in either stationary-phase or inoculated cells. No difference was observed in the length of the poly(A) tail between stationary-phase and inoculated cells. These results suggest that a certain postinoculation-specific regulatory factor participates in the destabilization of rmf mRNA and is dependent on polyadenylation.

Effects of pretreatments with sulfhydryls and alkylating agents on spheroplast formation from Schwanniomyces species

1984 ◽  
Vol 30 (3) ◽  
pp. 368-374 ◽  
Author(s):  
T. M. Dowhanick ◽  
C. J. Panchal ◽  
G. G. Stewart
Keyword(s):  
Cell Wall ◽  
Stationary Phase ◽  
Growth Phase ◽  
Cell Walls ◽  
Alkylating Agents ◽  
Inhibitory Effects ◽  
Late Stationary Phase ◽  
Stages Of Growth ◽  
Degradative Enzymes ◽  
Sulfhydryl Compounds

Pretreatment of cells with β-mercaptoethanol, dithiothreitol, or cysteine increased the rate of spheroplast formation at all stages of growth in Schwanniomyces castellii and S. occidentalis, but had little effect on final yields of spheroplasts when compared with controls. Pretreatment with iodoacetate and cystine resulted in decreased rates of formation and lower yields of spheroplasts at all stages of growth for both species. The enhanced rates of spheroplast formation in the presence of the sulfhydryl compounds were more pronounced when the experimental cells were derived from early or late stationary phase cultures, whereas the inhibitory effects of cystine and iodoacetate were not associated with the growth phase. In agreement with extant data on other yeast genera, sulfhydryl compounds increased the susceptibility of the yeast cell wall to degradative enzymes, whilst alkylating agents decreased susceptibility of cell walls to these enzymes.

scholarly journals RocA Regulates Phosphatase Activity of Virulence Sensor CovS of Group A Streptococcus in Growth Phase- and pH-Dependent Manners

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Chuan Chiang-Ni ◽  
He-Jing Chiou ◽  
Huei-Chuan Tseng ◽  
Chih-Yun Hsu ◽  
Cheng-Hsun Chiu
Keyword(s):  
Stationary Phase ◽  
Phosphatase Activity ◽  
Virulence Factor ◽  
Growth Phase ◽  
Exponential Phase ◽  
Acidic Stress ◽  
Phosphorylation Level ◽  
Factor Expression ◽  
Group A ◽  
Ph Dependent

ABSTRACT The control of the virulence response regulator and sensor (CovR-CovS) two-component regulatory system in group A Streptococcus (GAS) strains regulates more than 15% of gene expression and has critical roles in invasive GAS infection. The membrane-embedded CovS has kinase and phosphatase activities, and both are required for modulating the phosphorylation level of CovR. Regulator of Cov (RocA) is a positive regulator of covR and also been shown to be a pseudokinase that interacts with CovS to enhance the phosphorylation level of CovR; however, how RocA modulates the activity of CovS has not been determined conclusively. Although the phosphorylation level of CovR was decreased in the rocA mutant in the exponential phase, the present study shows that phosphorylated CovR in the rocA mutant increased to levels similar to those in the wild-type strain in the stationary phase of growth. In addition, acidic stress, which is generally present in the stationary phase, enhanced the phosphorylation level of CovR in the rocA mutant. The phosphorylation levels of CovR in the CovS phosphatase-inactivated mutant and its rocA mutant were similar under acidic stress and Mg2+ (the signal that inhibits CovS phosphatase activity) treatments, suggesting that the phosphatase activity, but not the kinase activity, of CovS is required for RocA to modulate CovR phosphorylation. The phosphorylation level of CovR is crucial for GAS strains to regulate virulence factor expression; therefore, the growth phase- and pH-dependent RocA activity would contribute significantly to GAS pathogenesis. IMPORTANCE The emergence of invasive group A streptococcal infections has been reported worldwide. Clinical isolates that have spontaneous mutations or a truncated allele of the rocA gene (e.g., emm3-type isolates) are considered to be more virulent than isolates with the intact rocA gene (e.g., emm1-type isolates). RocA is a positive regulator of covR and has been shown to enhance the phosphorylation level of intracellular CovR regulator through the functional CovS protein. CovS is the membrane-embedded sensor and modulates the phosphorylation level of CovR by its kinase and phosphatase activities. The present study shows that the enhancement of CovR phosphorylation is mediated via the repression of CovS’s phosphatase activity by RocA. In addition, we found that RocA acts dominantly on modulating CovR phosphorylation under neutral pH conditions and in the exponential phase of growth. The phosphorylation level of CovR is crucial for group A Streptococcus species to regulate virulence factor expression and is highly related to bacterial invasiveness; therefore, growth phase- and pH-dependent RocA activity and the sequence polymorphisms of rocA gene would contribute significantly to bacterial phenotype variations and pathogenesis.

scholarly journals The Nature of Antibacterial Adaptive Immune Responses against Staphylococcus aureus Is Dependent on the Growth Phase and Extracellular Peptidoglycan

2019 ◽  
Vol 88 (1) ◽  
Author(s):  
Payal P. Balraadjsing ◽  
Lisbeth D. Lund ◽  
Yuri Souwer ◽  
Sebastian A. J. Zaat ◽  
Hanne Frøkiær ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
T Cell ◽  
Stationary Phase ◽  
Growth Phase ◽  
Cell Response ◽  
Th17 Cell ◽  
Exponential Phase ◽  
Th1 Cell ◽  
Content Type

ABSTRACT Staphylococcus aureus has evolved different strategies to evade the immune response, which play an important role in its pathogenesis. The bacteria express and shed various cell wall components and toxins during different stages of growth that may affect the protective T cell responses to extracellular and intracellular S. aureus. However, if and how the dendritic cell (DC)-mediated T cell response against S. aureus changes during growth of the bacterium remain elusive. In this study, we show that exponential-phase (EP) S. aureus bacteria were endocytosed very efficiently by human DCs, and these DCs strongly promoted production of the T cell polarizing factor interleukin-12 (IL-12). In contrast, stationary-phase (SP) S. aureus bacteria were endocytosed less efficiently by DCs, and these DCs produced small amounts of IL-12. The high level of IL-12 production induced by EP S. aureus led to the development of a T helper 1 (Th1) cell response, which was inhibited after neutralization of IL-12. Furthermore, preincubation with the staphylococcal cell wall component peptidoglycan (PGN), characteristically shed during the exponential growth phase, modulated the DC response to EP S. aureus. PGN preincubation appeared to inhibit IL-12p35 expression, leading to downregulation of IL-12 and an increase of IL-23 production by DCs, enhancing Th17 cell development. Taken together, our data indicate that exponential-phase S. aureus bacteria induce a stronger IL-12-dependent Th1 cell response than stationary-phase S. aureus and that this Th1 cell response shifted toward a Th17 cell response in the presence of PGN.

scholarly journals Growth Phase Regulation of Vibrio cholerae RTX Toxin Export

2006 ◽  
Vol 189 (5) ◽  
pp. 1827-1835 ◽  
Author(s):  
Bethany Kay Boardman ◽  
Brian M. Meehan ◽  
Karla J. Fullner Satchell
Keyword(s):  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Growth Phase ◽  
Diarrheal Disease ◽  
Outer Membrane Vesicles ◽  
Transcriptional Level ◽  
Type I ◽  
Bacterial Membranes ◽  
Rtx Toxin ◽  
Phase Regulation

ABSTRACT Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, secretes several “accessory” toxins, including RTX toxin, which causes the cross-linking of the actin cytoskeleton. RTX toxin is exported to the extracellular milieu by an atypical type I secretion system (T1SS), and we previously noted that RTX-associated activity is detectable only in supernatant fluids from log phase cultures. Here, we investigate the mechanisms for regulating RTX toxin activity in supernatant fluids. We find that exported proteases are capable of destroying RTX activity and may therefore play a role in the growth phase regulation of toxin activity. We determined that the absence of RTX toxin in stationary-phase culture supernatant fluids is also due to a lack of toxin secretion and not attributable to solely proteolytic degradation. We ascertained that the T1SS apparatus is regulated at the transcriptional level by growth phase control that is independent of quorum sensing, unlike other virulence factors of V. cholerae. Additionally, in stationary-phase cultures, all RTX toxin activity is associated with bacterial membranes or outer membrane vesicles.

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