Molecular architecture of the lactococcal cell surface as it relates to important industrial properties

Gopal, Pramod K.; Reilly, Katrina I.

doi:10.1016/0958-6946(95)00046-1

Cited by 30 publications

(25 citation statements)

References 26 publications

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“…diacetilactis. Moreover, it is also in agreement with the fact that the phage receptors present at the surfaces of other strains of L. lactis were found to be located mainly on carbohydrate moieties (22,35,45,50).…”

Section: Discussionsupporting

confidence: 74%

“…The adhesion behavior of microbial cells has been shown to depend on the balance of electrostatic and van der Waals interactions and on the hydrophobic character of the surfaces involved (38,42,53,54), pointing to the possible influence of the respective zeta potentials and surface hydrophobicities. Moreover, the production of extracellular substances either at the cell surface or in the surrounding medium has been shown to influence adhesion (14, 55).The surface hydrophobicity and composition of lactic acid bacteria have been studied primarily by microbial adhesion to hydrocarbon (7,18,40,46,56) and by biochemical analysis (7,18,22,35,45,49,50,56), respectively. However, the relevance of these methods is questionable for interfacial phenomena.…”

mentioning

confidence: 99%

“…The surface hydrophobicity and composition of lactic acid bacteria have been studied primarily by microbial adhesion to hydrocarbon (7,18,40,46,56) and by biochemical analysis (7,18,22,35,45,49,50,56), respectively. However, the relevance of these methods is questionable for interfacial phenomena.…”

mentioning

confidence: 99%

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Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Boonaert

Rouxhet

2000

Appl Environ Microbiol

205

142

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The surface chemical composition and physicochemical properties (hydrophobicity and zeta potential) of two lactic acid bacteria, Lactococcus lactis subsp. lactis bv. diacetilactis and Lactobacillus helveticus, have been investigated using cells harvested in exponential or stationary growth phase. The surface composition determined by X-ray photoelectron spectroscopy (XPS) was converted into a molecular composition in terms of proteins, polysaccharides, and hydrocarbonlike compounds. The concentration of the last was always below 15% (wt/wt), which is related to the hydrophilic character revealed by water contact angles of less than 30°. The surfaces of L. lactis cells had a polysaccharide concentration about twice that of proteins. The S-layer of L. helveticus was either interrupted or crossed by polysaccharide-rich compounds; the concentration of the latter was higher in the stationary growth phase than in the exponential growth phase. Further progress was made in the interpretation of XPS data in terms of chemical functions by showing that the oxygen component at 531.2 eV contains a contribution of phosphate in addition to the main contribution of the peptide link. The isoelectric points were around 2 and 3, and the electrophoretic mobilities above pH 5 (ionic strength, 1 mM) were about ؊3.0 ؋ 10 ؊8 and ؊0.6 ؋ 10 ؊8 m 2 s ؊1 V ؊1 for L. lactis and L. helveticus, respectively. The electrokinetic properties of the latter reveal the influence of carboxyl groups, while the difference between the two strains is related to a difference between N/P surface concentration ratios, reflecting the relative exposure of proteins and phosphate groups at the surface.In many instances, the behavior of lactic acid bacteria is dependent on interfacial processes and thus on cell surface physicochemical properties and chemical composition. A better knowledge of these aspects would allow a deeper understanding of the autolysis of lactic acid bacteria (29, 36) and the production of texturing exopolysaccharides (4). It would help in controlling the sedimentation of starters for commercial production (7) and in understanding the roles of specific and nonspecific interactions in phage attachment (7,46,56).In dairy product manufacturing, adhesion of lactic bacteria to a material may be the first step leading to biofilm formation, which can be either deleterious (contamination, taste alteration, and biofouling on heat exchangers) (17, 25) or beneficial (continuous inoculation in yogurt or cheese making) (5). The adhesion behavior of microbial cells has been shown to depend on the balance of electrostatic and van der Waals interactions and on the hydrophobic character of the surfaces involved (38,42,53,54), pointing to the possible influence of the respective zeta potentials and surface hydrophobicities. Moreover, the production of extracellular substances either at the cell surface or in the surrounding medium has been shown to influence adhesion (14, 55).The surface hydrophobicity and composition of lactic acid bacteria have been studie...

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Section: Discussionsupporting

confidence: 74%

mentioning

confidence: 99%

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Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Boonaert

Rouxhet

2000

Appl Environ Microbiol

205

142

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“…8). The difference in the burst size estimates relative to liquid culture can be explained by environmental dependence (28), and molecular explanations for differing susceptibilities and adsorption have been proposed (6,12). However, these factors also can be explained by spatial effects: spatial colony heterogeneity, localized modification of the environment by hyphae (19), and the spatial distribution-correlation of phage and hosts throughout the microcosm.…”

Section: Discussionmentioning

confidence: 99%

“…The susceptibility of streptomycetes to phage infection varies with the age of the mycelia, with older mycelia being more resistant than young tips (11,22,30). This variation may be due to higher rates of DNA synthesis in hyphal-tip proximal regions (14) or to differences in the density of, or area covered by, surface receptor molecules (6,12). The replication rate of phage therefore depends on the rate of adsorption to, and infection of, susceptible hosts, transportation processes such as rates of diffusion of phage, and the burst size of the virus.…”

Section: Theorymentioning

confidence: 99%

Mathematical Analysis of Growth and Interaction Dynamics of Streptomycetes and a Bacteriophage in Soil

Burroughs¹,

Marsh

Wellington

2000

Appl Environ Microbiol

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We observed the infection cycle of the temperate actinophage KC301 in relation to the growth of its host Streptomyces lividans TK24 in sterile soil microcosms. Despite a large increase in phage population following germination of host spores, there was no observable impact on host population numbers as measured by direct plate counts. The only change in the host population following infection was the establishment of a small subpopulation of KC301 lysogens. The interaction of S. lividans and KC301 in soil was analyzed with a population-dynamic mathematical model to determine the underlying mechanisms of this low susceptibility to phage attack relative to aquatic environments. This analysis suggests that the soil environment is a highly significant component of the phage-host interaction, an idea consistent with earlier observations on the importance of the environment in determining host growth and phage-host dynamics. Our results demonstrate that the accepted phage-host interaction and host life cycle, as determined from agar plate studies and liquid culture, is sufficient for quantitative agreement with observations in soil, using soil-determined rates. There are four significant effects of the soil environment: (i) newly germinated spores are more susceptible to phage lysis than are hyphae of developed mycelia, (ii) substrate mycelia in mature colonies adsorb about 98% of the total phage protecting susceptible young hyphae from infection, (iii) the burst size of KC301 is large in soil (>150, 90% confidence) relative to that observed in liquid culture (120, standard error of the mean [SEM], 6), and (iv) there is no measurable impact on the host in terms of reduced growth by the phage. We hypothesize that spatial heterogeneity is the principal cause of these effects and is the primary determinant in bacterial escape of phage lysis in soil.The filamentous nature of streptomycetes causes two problems for their quantification in soil and interaction with phage. First, the identification of a lysable unit during phage infection as a proportion of a hypha is unclear; second, the rate of phage adsorption to hyphae is dependent upon the age of the hyphae (11,22,30). Phage interaction, therefore, changes over time as a function of colony heterogeneity. The effects of this heterogeneity are greatest in undisturbed colonies where interactions are dependent on diffusion. Growth on agar is limited to the boundary of the colony by the diffusion of nutrients and staling compounds (33). In contrast, colonies grown in liquid culture have little spatial heterogeneity since diffusion is rapid, and the uniform exposure of host to phage can result in efficient phage lysis (4). The effects of diffusion in soil are expected to be informed by, but distinct from, both of these cases and possibly underlies the environmental dependence observed in a number of systems (15,17,28).Our objective in this study was to use population-dynamic modeling of the phage-streptomycete interaction to quantify and characterize the growth of streptomycet...

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Surface properties of microbial cells probed at the nanometre scale with atomic force microscopy

Boonaert

Rouxhet

Dufrêne

2000

Surf. Interface Anal.

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Atomic force microscopy (AFM) was used to characterize, under water, the surface morphology and molecular interactions of two types of microbial cells: fungal spores (Phanerochaete chrysosporium) and bacteria (Lactococcus lactis). High-resolution deflection images showed that the spore surface was uniformly covered with patterns of rodlets that were several hundred nanometres in length and had a periodicity of 10 nm. Such surface organization was not detected on the bacterial surface, which showed a sponge-like structure. Force-distance curves revealed very different molecular interactions for the two microorganisms: upon approach, no significant curvature was seen in the contact region for spores, contrary to bacteria, pointing to a difference in cell softness; and upon retraction, no adhesion forces were detected on spores but multiple unbinding events and elongation forces attributed to macromolecular bridging were observed on bacteria. These results show that AFM is a powerful tool for probing the surface properties of native microbial cells on the nanometre scale.

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Molecular architecture of the lactococcal cell surface as it relates to important industrial properties

Cited by 30 publications

References 26 publications

Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Mathematical Analysis of Growth and Interaction Dynamics of Streptomycetes and a Bacteriophage in Soil

Surface properties of microbial cells probed at the nanometre scale with atomic force microscopy

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