Pullulan elaboration and differentiation of the resting forms in Aureobasidium pullulans

1995 ◽  
Vol 41 (1) ◽  
pp. 35-45 ◽  
Author(s):  
L. Simon ◽  
B. Bouchet ◽  
C. Caye-Vaugien ◽  
D. J. Gallant
Keyword(s):  
Cell Wall ◽  
Aureobasidium Pullulans ◽  
Culture Medium ◽  
Extracellular Polysaccharide ◽  
Growth Conditions ◽  
Cellular Level ◽  
Wall Thickening ◽  
Resting Forms ◽  
Polysaccharide Synthesis ◽  
Swollen Cell

To identify the cellular forms that are responsible for the synthesis of pullulan produced by Aureobasidium pullulans, we performed cytochemical and ultrastructural localizations of glucan in the cellular forms of this microorganism (blastospores and resting forms). Growth conditions, cell populations, and pullulan production were studied concurrently. Our results are consistent with a model in which the resting forms (swollen cells and chlamydospores) might be primarily involved in this extracellular polysaccharide elaboration. At the cellular level, pullulan production could be the result of three main stages: (i) cell wall thickening and extracellular polysaccharide synthesis by the swollen cell, (ii) fibrillar arrangement of this polysaccharide into pullulan along a capsular network around the chlamydospore, and (iii) subcellular hydrolysis separating the capsule from the periplasmic zone and consequently permitting the solubilization of pullulan in the culture medium. A melanization process in the outer layer of the cell wall and the capsule accompanies these patterns.Key words: Aureobasidium pullulans, capsule, cytochemistry, polysaccharide, pullulan, resting forms.

scholarly journals EXOPOLYSACCHARIDE SYNTHESIS PRODUCTIVITY BY BACILLUS MUCILAGINOSUS DEPENDING ON THE NITROGEN SOURCE AND ORIGIN OF INOCULUM

2015 ◽  
Vol 21 ◽  
pp. 12-17
Author(s):  
I. M. Malinovska
Keyword(s):  
Nitrogen Source ◽  
Culture Medium ◽  
Physiological State ◽  
Bacterial Biomass ◽  
Extracellular Polysaccharide ◽  
Potassium Nitrate ◽  
Bacillus Mucilaginosus ◽  
Vegetative Cells ◽  
Polysaccharide Synthesis ◽  
Sporulation Process

It was established that Bacillus mucilaginosus C-3 requires introduction of nitrogen sourceinto the culture medium in form of nitrate as themost optimal for maximal accumulation of bacterial biomass and sporulation process. Introduction of the ammonium form was less efficient. It was shown that the intensity of nitrogensource use by B. mucilaginosus is highly depended on the physiological state of the inoculum cells. At sowing of spore inoculum theoptimal concentration of potassium nitrate was2.5 g/l resulting in 1010 cells/ml, while under theuse of vegetative cells the optimal concentrationof potassium nitrate was 1.0 g/l leading to theaccumulation of 109 cells/ml.Use of spore inoculum had ensured themaximum productivity of extracellular polysaccharide synthesis. With the higher number ofB. mucilaginosus subcultures in a vegetativestate the efficiency of the exopolysaccharidesynthesis has decreased: after the second passage — by 20.0 %, after the fourth — by 56.5 %,after the sixth — at 127.8 %. After eighth passage the culture loses its ability to synthesizepolysaccharide, especially on the medium withthe N : C ratio 1 : 3 and resume this ability onlyafter sporulation and the significant increase ofthe N : C ratio.

Histological aspects of the cryopreservation of potato

2008 ◽  
Vol 56 (3) ◽  
pp. 341-348
Author(s):  
P. Pepó ◽  
A. Kovács
Keyword(s):  
Cell Wall ◽  
Low Temperatures ◽  
Cell Walls ◽  
Cellular Level ◽  
Adaptive Mechanism ◽  
Epidermal Layer ◽  
Freezing And Thawing ◽  
Meristematic Cells ◽  
Suitable Solution ◽  
Vacuolated Cells

Cryopreservation appears to be a suitable solution for the maintenance of potato germplasms. The protocol described in this paper can be applied for the vitrification and preservation of meristems. During histo-cytological studies it is possible to observe modifications at the cellular level and to understand the adaptive mechanism to low temperatures. Control potato meristem tissue contained a number of meristematic cells with a gradient of differentiation. After freezing there were a large number of vacuolated cells, some of which exhibited broken cell walls and plasmolysis. The thickening of the cell wall, giving them a sinuous appearance, was observed after freezing and thawing the meristems, with ruptures of the cuticle and epidermal layer.

scholarly journals A Metzincin and TIMP-Like Protein Pair of a Phage Origin Sensitize Listeria monocytogenes to Phage Lysins and Other Cell Wall Targeting Agents

2021 ◽  
Vol 9 (6) ◽  
pp. 1323
Author(s):  
Etai Boichis ◽  
Nadejda Sigal ◽  
Ilya Borovok ◽  
Anat A. Herskovits
Keyword(s):  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Mammalian Cells ◽  
Protein Pair ◽  
Growth Conditions ◽  
Wall Structure ◽  
Antibiotic Resistant ◽  
Extracellular Milieu ◽  
Virion Release ◽  
Genes Encoding

Infection of mammalian cells by Listeria monocytogenes (Lm) was shown to be facilitated by its phage elements. In a search for additional phage remnants that play a role in Lm’s lifecycle, we identified a conserved locus containing two XRE regulators and a pair of genes encoding a secreted metzincin protease and a lipoprotein structurally similar to a TIMP-family metzincin inhibitor. We found that the XRE regulators act as a classic CI/Cro regulatory switch that regulates the expression of the metzincin and TIMP-like genes under intracellular growth conditions. We established that when these genes are expressed, their products alter Lm morphology and increase its sensitivity to phage mediated lysis, thereby enhancing virion release. Expression of these proteins also sensitized the bacteria to cell wall targeting compounds, implying that they modulate the cell wall structure. Our data indicate that these effects are mediated by the cleavage of the TIMP-like protein by the metzincin, and its subsequent release to the extracellular milieu. While the importance of this locus to Lm pathogenicity remains unclear, the observation that this phage-associated protein pair act upon the bacterial cell wall may hold promise in the field of antibiotic potentiation to combat antibiotic resistant bacterial pathogens.

scholarly journals UDP-glucose dehydrogenases of maize: a role in cell wall pentose biosynthesis

2005 ◽  
Vol 391 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Anna Kärkönen ◽  
Alain Murigneux ◽  
Jean-Pierre Martinant ◽  
Elodie Pepey ◽  
Christophe Tatout ◽  
...  
Keyword(s):  
Cell Wall ◽  
Sequence Similarity ◽  
Glucose Dehydrogenase ◽  
Soya Bean ◽  
Amino Acid Sequences ◽  
Cell Wall Polysaccharide ◽  
Polysaccharide Biosynthesis ◽  
Polysaccharide Synthesis ◽  
Ethanol Dehydrogenase ◽  
Adh Activity

UDPGDH (UDP-D-glucose dehydrogenase) oxidizes UDP-Glc (UDP-D-glucose) to UDP-GlcA (UDP-D-glucuronate), the precursor of UDP-D-xylose and UDP-L-arabinose, major cell wall polysaccharide precursors. Maize (Zea mays L.) has at least two putative UDPGDH genes (A and B), according to sequence similarity to a soya bean UDPGDH gene. The predicted maize amino acid sequences have 95% similarity to that of soya bean. Maize mutants with a Mu-element insertion in UDPGDH-A or UDPGDH-B were isolated (udpgdh-A1 and udpgdh-B1 respectively) and studied for changes in wall polysaccharide biosynthesis. The udpgdh-A1 and udpgdh-B1 homozygotes showed no visible phenotype but exhibited 90 and 60–70% less UDPGDH activity respectively than wild-types in a radiochemical assay with 30 μM UDP-glucose. Ethanol dehydrogenase (ADH) activity varied independently of UDPGDH activity, supporting the hypothesis that ADH and UDPGDH activities are due to different enzymes in maize. When extracts from wild-types and udpgdh-A1 homozygotes were assayed with increasing concentrations of UDP-Glc, at least two isoforms of UDPGDH were detected, having Km values of approx. 380 and 950 μM for UDP-Glc. Leaf and stem non-cellulosic polysaccharides had lower Ara/Gal and Xyl/Gal ratios in udpgdh-A1 homozygotes than in wild-types, whereas udpgdh-B1 homozygotes exhibited more variability among individual plants, suggesting that UDPGDH-A activity has a more important role than UDPGDH-B in UDP-GlcA synthesis. The fact that mutation of a UDPGDH gene interferes with polysaccharide synthesis suggests a greater importance for the sugar nucleotide oxidation pathway than for the myo-inositol pathway in UDP-GlcA biosynthesis during post-germinative growth of maize.

Cell-wall abnormalities of a Chlamydomonas reinhardtii mutant strain under suboptimal growth conditions

Planta ◽  
1991 ◽  
Vol 183 (1) ◽  
Author(s):  
J�rgen Voigt ◽  
Dieter Mergenhagen ◽  
Irmhild Wachholz ◽  
Elsbeth Manshard ◽  
Marianne Mix
Keyword(s):  
Cell Wall ◽  
Chlamydomonas Reinhardtii ◽  
Mutant Strain ◽  
Growth Conditions

scholarly journals Anaerobic Conditions Induce Expression of Polysaccharide Intercellular Adhesin in Staphylococcus aureus and Staphylococcus epidermidis

2001 ◽  
Vol 69 (6) ◽  
pp. 4079-4085 ◽  
Author(s):  
Sarah E. Cramton ◽  
Martina Ulrich ◽  
Friedrich Götz ◽  
Gerd Döring
Keyword(s):  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Extracellular Polysaccharide ◽  
Growth Conditions ◽  
Anaerobic Conditions ◽  
Anaerobic Environment ◽  
Specific Mrna

ABSTRACT Products of the intercellular adhesion (ica) operon in Staphylococcus aureus and Staphylococcus epidermidis synthesize a linear β-1,6-linked glucosaminylglycan. This extracellular polysaccharide mediates bacterial cell-cell adhesion and is required for biofilm formation, which is thought to increase the virulence of both pathogens in association with prosthetic biomedical implants. The environmental signal(s) that triggers ica gene product and polysaccharide expression is unknown. Here we demonstrate that anaerobic in vitro growth conditions lead to increased polysaccharide expression in both S. aureus and S. epidermidis, although the regulation is less stringent inS. epidermidis. Anaerobiosis also dramatically stimulates ica-specific mRNA expression inica- and polysaccharide-positive strains of both S. aureus and S. epidermidis.These data suggest a mechanism whereby ica gene expression and polysaccharide production may act as a virulence factor in an anaerobic environment in vivo.

scholarly journals Nutritionally variant streptococci.

1991 ◽  
Vol 4 (2) ◽  
pp. 184-190 ◽  
Author(s):  
K L Ruoff
Keyword(s):  
Cell Wall ◽  
Oral Cavity ◽  
Successful Treatment ◽  
Distinct Species ◽  
Growth Conditions ◽  
Clinical Specimens ◽  
Wide Range ◽  
Streptococcal Species ◽  
A Cell

Streptococci requiring either pyridoxal or L-cysteine for growth were first observed 30 years ago as organisms forming satellite colonies adjacent to colonies of "helper" bacteria. Although they were previously considered nutritional mutants of viridans streptococcal species, the nutritionally variant streptococci (NVS) are currently thought to belong to distinct species of the genus Streptococcus. NVS strains may display pleomorphic cellular morphologies, depending on their growth conditions, and are distinguished from most other streptococci by enzymatic and serological characteristics and the presence of a cell wall chromophore. NVS are found as normal inhabitants of the oral cavity, and in addition to their participation in endocarditis, they have been isolated from a wide range of clinical specimens. Endocarditis caused by NVS is often difficult to eradicate; combinations of penicillin and an aminoglycoside are recommended for treatment. The unique physiological features of the NVS contribute to the difficulties encountered in their recovery from clinical specimens and may play a role in the problems associated with successful treatment of NVS endocarditis.

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