Studies of Freshwater Bacteria

Henrici, Arthur T.

doi:10.1128/jb.25.3.277-287.1933

Cited by 171 publications

(27 citation statements)

References 2 publications

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“…The first observation of surface‐associated aggregated bacteria was made by Antonie van Leeuwenhoek in 1684 when he described the ‘animals’ present in the plaque on teeth. Photomicrographs of aggregating bacteria were produced in 1933 by Henrici and he observed that ‘It is quite evident that for the most part water bacteria are not free floating organisms, but grow upon submerged surfaces’. For the purpose of this thesis, microbiology may be divided into two fields: environmental and medical.…”

Section: Introductionmentioning

confidence: 99%

The role of bacterial biofilms in chronic infections

Bjarnsholt

2013

APMIS

956

649

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Acute infections caused by pathogenic bacteria have been studied extensively for well over 100 years. These infections killed millions of people in previous centuries, but they have been combated effectively by the development of modern vaccines, antibiotics and infection control measures. Most research into bacterial pathogenesis has focused on acute infections, but these diseases have now been supplemented by a new category of chronic infections caused by bacteria growing in slime‐enclosed aggregates known as biofilms. Biofilm infections, such as pneumonia in cystic fibrosis patients, chronic wounds, chronic otitis media and implant‐ and catheter‐associated infections, affect millions of people in the developed world each year and many deaths occur as a consequence. In general, bacteria have two life forms during growth and proliferation. In one form, the bacteria exist as single, independent cells (planktonic) whereas in the other form, bacteria are organized into sessile aggregates. The latter form is commonly referred to as the biofilm growth phenotype. Acute infections are assumed to involve planktonic bacteria, which are generally treatable with antibiotics, although successful treatment depends on accurate and fast diagnosis. However, in cases where the bacteria succeed in forming a biofilm within the human host, the infection often turns out to be untreatable and will develop into a chronic state. The important hallmarks of chronic biofilm‐based infections are extreme resistance to antibiotics and many other conventional antimicrobial agents, and an extreme capacity for evading the host defences. In this thesis, I will assemble the current knowledge on biofilms with an emphasis on chronic infections, guidelines for diagnosis and treatment of these infections, before relating this to my previous research into the area of biofilms. I will present evidence to support a view that the biofilm lifestyle dominates chronic bacterial infections, where bacterial aggregation is the default mode, and that subsequent biofilm development progresses by adaptation to nutritional and environmental conditions. I will make a series of correlations to highlight the most important aspects of biofilms from my perspective, and to determine what can be deduced from the past decades of biofilm research. I will try to bridge in vitro and in vivo research and propose methods for studying biofilms based on this knowledge. I will compare how bacterial biofilms exist in stable ecological habitats and opportunistically in unstable ecological habitats, such as infections. Bacteria have a similar lifestyle (the biofilm) in both habitats, but the fight for survival and supremacy is different. On the basis of this comparison, I will hypothesize how chronic biofilm infections are initiated and how bacteria live together in these infections. Finally, I will discuss different aspects of biofilm infection diagnosis. Hopefully, this survey of current knowledge and my proposed guidelines will provide the basis and inspiration for more research,...

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Section: Introductionmentioning

confidence: 99%

The role of bacterial biofilms in chronic infections

Bjarnsholt

2013

APMIS

956

649

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“…Despite the existence of diverse machineries to sense, adhere to, and proliferate on surfaces, it is commonly observed that bacteria initially seem to have a difficult time attaching to a surface, as indicated by typical flow cell studies where P. aeruginosa often takes Ͼ20 h before attaching to the surface in large numbers (25,26). This phenomenon was first reported in the 1930s (27,28). Using high-speed microscopy to measure the distribution of surface residence times, it was previously observed that the overwhelming majority of cells that land on the surface eventually detach, and it is only after a prolonged and variable time lag that cells begin to rapidly cover the surface (8).…”

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confidence: 99%

Social Cooperativity of Bacteria during Reversible Surface Attachment in Young Biofilms: a Quantitative Comparison of Pseudomonas aeruginosa PA14 and PAO1

Lee

Vachier

Anda

et al. 2020

mBio

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What are bacteria doing during “reversible attachment,” the period of transient surface attachment when they initially engage a surface, besides attaching themselves to the surface? Can an attaching cell help any other cell attach? If so, does it help all cells or employ a more selective strategy to help either nearby cells (spatial neighbors) or its progeny (temporal neighbors)? Using community tracking methods at the single-cell resolution, we suggest answers to these questions based on how reversible attachment progresses during surface sensing for Pseudomonas aeruginosa strains PAO1 and PA14. Although PAO1 and PA14 exhibit similar trends of surface cell population increase, they show unanticipated differences when cells are considered at the lineage level and interpreted using the quantitative framework of an exactly solvable stochastic model. Reversible attachment comprises two regimes of behavior, processive and nonprocessive, corresponding to whether cells of the lineage stay on the surface long enough to divide, or not, before detaching. Stark differences between PAO1 and PA14 in the processive regime of reversible attachment suggest the existence of two surface colonization strategies. PAO1 lineages commit quickly to a surface compared to PA14 lineages, with early c-di-GMP-mediated exopolysaccharide (EPS) production that can facilitate the attachment of neighbors. PA14 lineages modulate their motility via cyclic AMP (cAMP) and retain memory of the surface so that their progeny are primed for improved subsequent surface attachment. Based on the findings of previous studies, we propose that the differences between PAO1 and PA14 are potentially rooted in downstream differences between Wsp-based and Pil-Chp-based surface-sensing systems, respectively. IMPORTANCE The initial pivotal phase of bacterial biofilm formation known as reversible attachment, where cells undergo a period of transient surface attachment, is at once universal and poorly understood. What is more, although we know that reversible attachment culminates ultimately in irreversible attachment, it is not clear how reversible attachment progresses phenotypically, as bacterial surface-sensing circuits fundamentally alter cellular behavior. We analyze diverse observed bacterial behavior one family at a time (defined as a full lineage of cells related to one another by division) using a unifying stochastic model and show that our findings lead to insights on the time evolution of reversible attachment and the social cooperative dimension of surface attachment in PAO1 and PA14 strains.

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“…The interactions between attached bacteria and adsorbed nutrients have been well documented [1, 2, 23–33], but the results of those studies give an inconsistent picture of what occurs when both bacteria and nutrient become immobilised at a solid–liquid surface. In some cases the adsorption of nutrients resulted in recalcitrance of an otherwise readily biodegradable substrate [26, 31], whereas the study of Griffith and Fletcher [2] reported that attached bacteria benefited from nutrients adsorbed to a common surface.…”

Section: Discussionmentioning

confidence: 99%

Effect of river sediment on the biodegradation kinetics of surfactant and non-surfactant compounds

Marchesi

White

Russell

et al. 2006

FEMS Microbiology Ecology

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The half‐time of biodegradation of the surfactant sodium dodecylsulfate (SDS) by Pseudomonas species C12B, was reduced two fold by the presence of a riverine sediment. The sediment alone gave comparatively negligible biodegradation of SDS under otherwise equivalent conditions. The sediment had no effect on the kinetics of biodegradation of the non‐surfactant pyruvate by Pseudomonas strain C12B. In the light of (i) the known strong adsorption of the surfactant SDS, but not pyruvate, to river sediment and (ii) the SDS‐stimulated attachment of Pseudomonas C12B and other SDS‐degraders to the sediment, the above observations indicate that acceleration of biodegradation was the result of simultaneous attachment of both SDS and biodegradation competent bacteria to the sediment. This interpretation was strengthened by analysis of the biodegradation kinetics. The data obtained for biodegradation in the absence of sediment, were fitted best by a model involving logistic growth on the added surfactant. The biodegradation data in the presence of sediment were fitted to variants of this model, including one allowing growth on material endogenous to the sediment. Of the several models tested, the data were fitted best by one which is consistent with accumulation of both bacterial cells and substrate at the sediment surface. The enhancement of surfactant biodegradation by sediment is discussed in the context of the design of biodegradability tests and environmental acceptability.

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Studies of Freshwater Bacteria

Cited by 171 publications

References 2 publications

The role of bacterial biofilms in chronic infections

The role of bacterial biofilms in chronic infections

Social Cooperativity of Bacteria during Reversible Surface Attachment in Young Biofilms: a Quantitative Comparison of Pseudomonas aeruginosa PA14 and PAO1

Effect of river sediment on the biodegradation kinetics of surfactant and non-surfactant compounds

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