The use of ultrasonic imaging to evaluate the effect of protozoan grazing and movement on the topography of bacterial biofilms

Parry, Jacqueline D.; Holmes, A.K.; Unwin, M. E.; Laybourn‐Parry, Johanna

doi:10.1111/j.1472-765x.2007.02213.x

Cited by 18 publications

(16 citation statements)

References 36 publications

(89 reference statements)

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“…The susceptibility of P. costantinii and S. plymuthica biofilms to Tetrahymena sp. grazing is consistent with prior studies in which filterfeeding ciliates have been found to graze efficiently upon biofilms and induce significant changes in biofilm morphology (25,47,71).…”

Section: Discussionsupporting

confidence: 80%

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Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Dopheide

Lear

Stott

et al. 2011

Appl Environ Microbiol

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Protozoa are important components of microbial food webs, but protozoan feeding preferences and their effects in the context of bacterial biofilms are not well understood. The feeding interactions of two contrasting ciliates, the free-swimming filter feeder Tetrahymena sp. and the surface-associated predator Chilodonella sp., were investigated using biofilm-forming bacteria genetically modified to express fluorescent proteins. According to microscopy, both ciliates readily consumed cells from both Pseudomonas costantinii and Serratia plymuthica biofilms. When offered a choice between spatially separated biofilms, each ciliate showed a preference for P. costantinii biofilms. Experiments with bacterial cell extracts indicated that both ciliates used dissolved chemical cues to locate biofilms. Chilodonella sp. evidently used bacterial chemical cues as a basis for preferential feeding decisions, but it was unclear whether Tetrahymena sp. did also. Confocal microscopy of live biofilms revealed that Tetrahymena sp. had a major impact on biofilm morphology, forming holes and channels throughout S. plymuthica biofilms and reducing P. costantinii biofilms to isolated, grazing-resistant microcolonies. Grazing by Chilodonella sp. resulted in the development of less-defined trails through S. plymuthica biofilms and caused P. costantinii biofilms to become homogeneous scatterings of cells. It was not clear whether the observed feeding preferences for spatially separated P. costantinii biofilms over S. plymuthica biofilms resulted in selective targeting of P. costantinii cells in mixed biofilms. Grazing of mixed biofilms resulted in the depletion of both types of bacteria, with Tetrahymena sp. having a larger impact than Chilodonella sp., and effects similar to those seen in grazed single-species biofilms.

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Section: Discussionsupporting

confidence: 80%

“…may be relatively less successful at feeding upon biofilm cells than suspension feeders. However, comparable ingestion rates have been reported for other surface-dwelling protozoa such as amoebae and Tetrahymena feeding on attached bacteria in mixed-species biofilm (47).…”

Section: Discussionmentioning

confidence: 93%

Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Dopheide

Lear

Stott

et al. 2011

Appl Environ Microbiol

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“…Protozoans in biofilms can have strong impacts on bacterial abundances and spatial heterogeneity, bacterial and microalgal species assemblages, biofilm architecture, and sloughing dynamics (Jackson & Jones 1991, McCormick 1991, Arndt et al 2003, Parry 2004, Parry et al 2007). The diverse protozoans in biofilms have complex trophic interactions, seasonal variations, successional dynamics, and constraints from the flow regime and other environmental factors (Franco et al 1998, Sekar et al 2002, Arndt et al 2003, Gong et al 2005, Wey et al 2008, Norf et al 2009, Risse-Buhl & Küsel 2009.…”

Section: Introductionmentioning

confidence: 99%

Influences of biofilm-associated ciliates on the settlement of marine invertebrate larvae

Shimeta¹,

Cutajar²,

Watson³

et al. 2012

Mar. Ecol. Prog. Ser.

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Settlement of benthic marine invertebrate larvae often limits recruitment, influencing the structure and dynamics of natural populations as well as biofouling of marine infrastructure, ship hulls, and aquaculture operations. Certain microbial components of substratum biofilms influence settlement (e.g. bacteria, diatoms), but the importance of biofilm protozoa has been unknown. We tested for effects of ciliates by comparing settlement and survival of common fouling invertebrates among 3 biofilm conditions: no biofilm, a purely bac terial biofilm, and a biofilm of bacteria and ciliates. With an assemblage of 7 ciliates (from Hypotrichia, Haptoria, and Scuticociliatia), the serpulid polychaete Galeolaria caespitosa showed a 44 to 49% average reduction in settlement rate compared to the purely bacterial biofilm, and post-settlement mortality increased 7-fold to 34%. In contrast, settlement and survival of the bryozoan Bugula neritina were unaffected. With a partially different assemblage of 11 ciliates (from Hypotrichia, Sticho trichia, Haptoria, Colpodida, and Scuticociliatia), settle ment of the serpulid Pomatoceros taeniata more than doubled, whereas that of the blue mussel Mytilus galloprovincialis was reduced by 54% compared to the purely bacterial biofilm. The results could not be explained by ciliates changing the total abundance of biofilm bacteria. We hypothesize that mechanisms could include direct interactions between larvae and ciliates (physical interactions, interference from ciliates' feeding currents, or responses to chemicals from ciliates), or indirect effects from ciliates altering the bacterial assemblage or its settlement cues. Such large and species-specific effects of ciliates on larval settlement and postsettlement mortality might impact invertebrate recruitment rates and species assemblages, especially because biofilm ciliates are highly variable over time and space.Aggregation of the tubeworm Galeolaria caespitosa. Larval settlement of these and other invertebrates is influenced by ciliates on the substratum.

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“…Laboratory studies have demonstrated that certain specialized grazers are able to efficiently utilize mature bacterial biofilms (Huws et al 2005, Weitere et al 2005). Whether or not surfaceattached microcolonies are resistant to grazing, and if their formation is stimulated by the presence of grazers, might thus be dependent on the dominant grazer types present in the biofilms (Parry et al 2007). Experiments with natural, complex grazer communities are needed to test the role of protozoan grazers in controlling bacterial biofilms in the field.…”

Section: Introductionmentioning

confidence: 99%

Effects of protozoan grazing within river biofilms under semi-natural conditions

Wey¹,

Scherwaß²,

Norf³

et al. 2008

Aquat. Microb. Ecol.

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Biofilms play an important role in the material flux of many aquatic ecosystems, but little is known about the mechanisms controlling their community structure under natural conditions. In the present study, we focused on the effects of ciliates on the quantity and taxonomic composition of heterotrophic flagellates (HF), and the effects of HF on the quantity and life forms (single cells vs. microcolonies) of bacteria in the early phase of biofilm colonization. For this purpose, we established semi-natural biofilms in flow cells connected to the river Rhine at Cologne, Germany. Using filter cartridges, we size-fractionated the potamoplankton, which is the source of the biofilm community, thus establishing biofilms containing (1) only bacteria (1.2 µm filter), (2) HF and bacteria (8 or 5 µm filter), or (3) ciliates, HF and bacteria (20 µm filter). The presence of ciliates negatively influenced the abundance of biofilm-dwelling HF and selectively altered the taxonomic composition of the HF community. The presence of HF resulted in a significant reduction in the abundance of single bacterial cells, but enhanced the abundance of bacterial microcolonies. Furthermore, the presence of ciliates stimulated the abundance of single-cell bacteria (probably due to an HF-mediated trophic cascade), but had no effect on bacterial microcolonies. Taken together, the results of this study show the importance of protozoan grazing in shaping the species composition and morphology of early river biofilms under semi-natural conditions.

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The use of ultrasonic imaging to evaluate the effect of protozoan grazing and movement on the topography of bacterial biofilms

Cited by 18 publications

References 36 publications

Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Preferential Feeding by the Ciliates Chilodonella and Tetrahymena spp. and Effects of These Protozoa on Bacterial Biofilm Structure and Composition

Influences of biofilm-associated ciliates on the settlement of marine invertebrate larvae

Effects of protozoan grazing within river biofilms under semi-natural conditions

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