scholarly journals Lessons in Membrane Engineering for Octanoic Acid Production from EnvironmentalEscherichia coliIsolates

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Yingxi Chen ◽  
Michael Reinhardt ◽  
Natalia Neris ◽  
Lucas Kerns ◽  
Thomas J. Mansell ◽  
...  
Keyword(s):  
Cell Surface ◽  
Acid Production ◽  
Octanoic Acid ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Strain Mg1655 ◽  
Fatty Acid Production ◽  
Content Type ◽  
Fuels And Chemicals ◽  
Membrane Engineering

ABSTRACTFermentative production of many attractive biorenewable fuels and chemicals is limited by product toxicity in the form of damage to the microbial cell membrane. Metabolic engineering of the production organism can help mitigate this problem, but there is a need for identification and prioritization of the most effective engineering targets. Here, we use a set of previously characterized environmentalEscherichia coliisolates with high tolerance and production of octanoic acid, a model membrane-damaging biorenewable product, as a case study for identifying and prioritizing membrane engineering strategies. This characterization identified differences in the membrane lipid composition, fluidity, integrity, and cell surface hydrophobicity from those of the lab strain MG1655. Consistent with previous publications, decreased membrane fluidity was associated with increased fatty acid production ability. Maintenance of high membrane integrity or longer membrane lipids seemed to be of less importance than fluidity. Cell surface hydrophobicity was also directly associated with fatty acid production titers, with the strength of this association demonstrated by plasmid-based expression of the multiple stress resistance outer membrane protein BhsA. This expression ofbhsAwas effective in altering hydrophobicity, but the direction and magnitude of the change differed between strains. Thus, additional strategies are needed to reliably engineer cell surface hydrophobicity. This work demonstrates the ability of environmental microbiological studies to impact the metabolic engineering design-build-test-learn cycle and possibly increase the economic viability of fermentative bioprocesses.IMPORTANCEThe production of bulk fuels and chemicals in a bio-based fermentation process requires high product titers. This is often difficult to achieve, because many of the target molecules damage the membrane of the microbial cell factory. Engineering the composition of the membrane in order to decrease its vulnerability to this damage has proven to be an effective strategy for improving bioproduction, but additional strategies and engineering targets are needed. Here, we studied a small set of environmentalEscherichia coliisolates that have higher production titers of octanoic acid, a model biorenewable chemical, than those of the lab strain MG1655. We found that membrane fluidity and cell surface hydrophobicity are strongly associated with improved octanoic acid production. Fewer genetic modification strategies have been demonstrated for tuning hydrophobicity relative to fluidity, leading to the conclusion that there is a need for expanding hydrophobicity engineering strategies inE. coli.

scholarly journals Variation in Cell Surface Hydrophobicity among Cryptococcus neoformans Strains Influences Interactions with Amoebas

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Raghav Vij ◽  
Carina Danchik ◽  
Conor Crawford ◽  
Quigly Dragotakes ◽  
Arturo Casadevall
Keyword(s):  
Cell Surface ◽  
Cryptococcus Neoformans ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Natural Soil ◽  
Order Structure ◽  
Hydroxyl Groups ◽  
Biophysical Properties ◽  
Content Type ◽  
Biophysical Parameter

ABSTRACT Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces. C. neoformans is encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of some C. neoformans and C. gattii strains. The capsular polysaccharides of C. neoformans strains differ in repeating motifs and therefore vary in the number of hydroxyl groups, which, along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. We found that cell wall composition, in the context of chitin-chitosan content, does not influence CSH. For C. neoformans, CSH correlated with phagocytosis by natural soil predator Acanthamoeba castellanii. Furthermore, capsular binding of the protective antibody (18B7), but not the nonprotective antibody (13F1), altered the CSH of C. neoformans strains. Variability in CSH could be an important characteristic in comparing the biological properties of cryptococcal strains. IMPORTANCE The interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the cell surface hydrophobicity (CSH), is a biophysical parameter that varies among different strains of Cryptococcus neoformans. The CSH influences the phagocytosis of the yeast by its natural predator in the soil, the amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction and host-pathogen interaction in a damage-response framework.

scholarly journals n-Alkane Chain Length Alters Dietzia sp. Strain DQ12-45-1b Biosurfactant Production and Cell Surface Activity

2012 ◽  
Vol 79 (1) ◽  
pp. 400-402 ◽  
Author(s):  
Xing-Biao Wang ◽  
Yong Nie ◽  
Yue-Qin Tang ◽  
Gang Wu ◽  
Xiao-Lei Wu
Keyword(s):  
Cell Surface ◽  
Carbon Sources ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Biosurfactant Production ◽  
Content Type ◽  
Emulsification Activity ◽  
Negative Effect ◽  
Alkane Chain ◽  
Chain Lengths

ABSTRACTUpon growth onn-hexadecane (C16),n-tetracosane (C24), andn-hexatriacontane (C36),Dietziasp. strain DQ12-45-1b could produce different glycolipids, phospholipids, and lipopeptides. Interestingly, cultivation with C36increased cell surface hydrophobic activity, which attenuated the negative effect of the decline of the emulsification activity. These results suggest that the mechanisms of biosurfactant production and cell surface hydrophobicity are dependent upon the chain lengths of then-alkanes used as carbon sources.

scholarly journals Membrane Vesicle Formation as a Multiple-Stress Response Mechanism Enhances Pseudomonas putida DOT-T1E Cell Surface Hydrophobicity and Biofilm Formation

2012 ◽  
Vol 78 (17) ◽  
pp. 6217-6224 ◽  
Author(s):  
Thomas Baumgarten ◽  
Stefanie Sperling ◽  
Jana Seifert ◽  
Martin von Bergen ◽  
Frank Steiniger ◽  
...  
Keyword(s):  
Stress Response ◽  
Cell Surface ◽  
Pseudomonas Putida ◽  
Biofilm Formation ◽  
Membrane Vesicle ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Outer Membrane Vesicles ◽  
Stress Factors ◽  
Content Type

ABSTRACTAmong the adaptive responses of bacteria to rapid changes in environmental conditions, those of the cell envelope are known to be the most crucial. Therefore, several mechanisms with which bacteria change their cell surface and membranes in the presence of different environmental stresses have been elucidated. Among these mechanisms, the release of outer membrane vesicles (MV) in Gram-negative bacteria has attracted particular research interest because of its involvement in pathogenic processes, such as that ofPseudomonas aeruginosabiofilm formation in cystic fibrosis lungs. In this study, we investigated the role of MV formation as an adaptive response ofPseudomonas putidaDOT-T1E to several environmental stress factors and correlated it to the formation of biofilms. In the presence of toxic concentrations of long-chain alcohols, under osmotic stress caused by NaCl, in the presence of EDTA, and after heat shock, cells of this strain released MV within 10 min in the presence of a stressor. The MV formed showed similar size and charge properties, as well as comparable compositions of proteins and fatty acids. MV release caused a significant increase in cell surface hydrophobicity, and an enhanced tendency to form biofilms was demonstrated in this study. Therefore, the release of MV as a stress response could be put in a physiological context.

scholarly journals Helicobacter pylori Resists the Antimicrobial Activity of Calprotectin via Lipid A Modification and Associated Biofilm Formation

mBio ◽  
2015 ◽  
Vol 6 (6) ◽  
Author(s):  
Jennifer A. Gaddy ◽  
Jana N. Radin ◽  
Thomas W. Cullen ◽  
Walter J. Chazin ◽  
Eric P. Skaar ◽  
...  
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Lipid A ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Content Type ◽  
Bacterial Fitness ◽  
H Pylori

ABSTRACTHelicobacter pyloriis one of several pathogens that persist within the host despite a robust immune response.H. pylorielicits a proinflammatory response from host epithelia, resulting in the recruitment of immune cells which manifests as gastritis. Relatively little is known about howH. pylorisurvives antimicrobials, including calprotectin (CP), which is present during the inflammatory response. The data presented here suggest that one wayH. pylorisurvives the nutrient sequestration by CP is through alteration of its outer membrane. CP-treatedH. pyloridemonstrates increased bacterial fitness in response to further coculture with CP. Moreover, CP-treatedH. pyloricultures form biofilms and demonstrate decreased cell surface hydrophobicity. In response to CP, theH. pyloriLpx lipid A biosynthetic enzymes are not fully functional. The lipid A molecules observed inH. pyloricultures treated with CP indicate that the LpxF, LpxL, and LpxR enzyme functions are perturbed. Transcriptional analysis oflpxF,lpxL, andlpxRindicates that metal restriction by CP does not control this pathway through transcriptional regulation. Analyses ofH. pylorilpx mutants reveal that loss of LpxF and LpxL results in increased fitness, similar to what is observed in the presence of CP; moreover, these mutants have significantly increased biofilm formation and reduced cell surface hydrophobicity. Taken together, these results demonstrate a novel mechanism ofH. pyloriresistance to the antimicrobial activity of CP via lipid A modification strategies and resulting biofilm formation.IMPORTANCEHelicobacter pylorievades recognition of the host's immune system by modifying the lipid A component of lipopolysaccharide. These results demonstrate for the first time that the lipid A modification pathway is influenced by the host's nutritional immune response.H. pylori's exposure to the host Mn- and Zn-binding protein calprotectin perturbs the function of 3 enzymes involved in the lipid A modification pathway. Moreover, CP treatment ofH. pylori, or mutants with an altered lipid A, exhibit increased bacterial fitness and increased biofilm formation. This suggests thatH. pylorimodifies its cell surface structure to survive under the stress imposed by the host immune response. These results provide new insights into the molecular mechanisms that influence the biofilm lifestyle and how endotoxin modification, which rendersH. pyloriresistant to cationic antimicrobial peptides, can be inactivated in response to sequestration of nutrient metals.

scholarly journals Biosynthesis of β-(1→5)-Galactofuranosyl Chains of Fungal-Type and O-Mannose-Type Galactomannans within the Invasive Pathogen Aspergillus fumigatus

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuria Chihara ◽  
Yutaka Tanaka ◽  
Minoru Izumi ◽  
Daisuke Hagiwara ◽  
Akira Watanabe ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Aspergillus Fumigatus ◽  
Pathogenic Fungus ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Wall Structure ◽  
Fungal Cell ◽  
Content Type ◽  
Animal Pathogens

ABSTRACT The pathogenic fungus Aspergillus fumigatus contains galactomannans localized on the surface layer of its cell walls, which are involved in various biological processes. Galactomannans comprise α-(1→2)-/α-(1→6)-mannan and β-(1→5)-/β-(1→6)-galactofuranosyl chains. We previously revealed that GfsA is a β-galactofuranoside β-(1→5)-galactofuranosyltransferase involved in the biosynthesis of β-(1→5)-galactofuranosyl chains. In this study, we clarified the biosynthesis of β-(1→5)-galactofuranosyl chains in A. fumigatus. Two paralogs exist within A. fumigatus: GfsB and GfsC. We show that GfsB and GfsC, in addition to GfsA, are β-galactofuranoside β-(1→5)-galactofuranosyltransferases by biochemical and genetic analyses. GfsA, GfsB, and GfsC can synthesize β-(1→5)-galactofuranosyl oligomers at up to lengths of 7, 3, and 5 galactofuranoses within an established in vitro highly efficient assay of galactofuranosyltransferase activity. Structural analyses of galactomannans extracted from ΔgfsB, ΔgfsC, ΔgfsAC, and ΔgfsABC strains revealed that GfsA and GfsC synthesized all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans and that GfsB exhibited limited function in A. fumigatus. The loss of β-(1→5)-galactofuranosyl residues decreased the hyphal growth rate and conidium formation ability and increased the abnormal hyphal branching structure and cell surface hydrophobicity, but this loss is dispensable for sensitivity to antifungal agents and virulence toward immunocompromised mice. IMPORTANCE β-(1→5)-Galactofuranosyl residues are widely distributed in the subphylum Pezizomycotina of the phylum Ascomycota. Pezizomycotina includes many plant and animal pathogens. Although the structure of β-(1→5)-galactofuranosyl residues of galactomannans in filamentous fungi was discovered long ago, it remains unclear which enzyme is responsible for biosynthesis of this glycan. Fungal cell wall formation processes are complicated, and information concerning glycosyltransferases is essential for understanding them. In this study, we showed that GfsA and GfsC are responsible for the biosynthesis of all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans. The data presented here indicate that β-(1→5)-galactofuranosyl residues are involved in cell growth, conidiation, polarity, and cell surface hydrophobicity. Our new understanding of β-(1→5)-galactofuranosyl residue biosynthesis provides important novel insights into the formation of the complex cell wall structure and the virulence of the members of the subphylum Pezizomycotina.

Autecology of scum producing bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 527-530 ◽  
Author(s):  
Hilde Lemmer ◽  
George Lind ◽  
Margit Schade ◽  
Birgit Ziegelmayer
Keyword(s):  
Wastewater Treatment ◽  
Cell Surface ◽  
Wastewater Treatment Plants ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Residence Times ◽  
Loading Conditions ◽  
Emulsifying Activity ◽  
Substrate Preferences

Non-filamentous hydrophobic scum bacteria were isolated from scumming wastewater treatment plants (WWTP) by means of adhesion to hydrocarbons. They were characterized with respect to taxonomy, substrate preferences, cell surface hydrophobicity, and emulsification capability. Their role during flotation events is discussed. Rhodococci are selected by hydrolysable substrates and contribute to flotation both by cell surface hydrophobicity and emulsifying activity at long mean cell residence times (MCRT). Saprophytic Acinetobacter strains are able to promote flotation by hydrophobicity and producing emulsifying agents under conditions when hydrophobic substrates are predominant. Hydrogenophaga and Acidovorax species as well as members of the Cytophaga/Flavobacterium group are prone to proliferate under low loading conditions and contribute to flotation mainly by emulsification.

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