High-resolution imaging of pelagic bacteria by Atomic Force Microscopy and implications for carbon cycling

Malfatti, Francesca; Samo, Ty; Azam, Farooq

doi:10.1038/ismej.2009.116

Cited by 37 publications

(35 citation statements)

References 56 publications

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“…An intriguing observation is that inhibition of MIT9313 by an Alteromonas strain required proximity between the heterotrophic bacteria and MIT9313-that is, the effect could not be mimicked when the cells were kept apart by a semi-permeable membrane. Recently, close physical association (cell-cell contact) has been observed in natural seawater samples between Synechococcus cells, which are closely related to Prochlorococcus, and heterotrophic bacteria of unknown taxonomy (Malfatti and Azam, 2009;Malfatti et al, 2010). These observations suggest the potential for close or contact-mediated interactions even in tiny picoplankton cells.…”

Section: Prochlorococcus-heterotroph Interactions D Sher Et Almentioning

confidence: 93%

Response of Prochlorococcus ecotypes to co-culture with diverse marine bacteria

et al. 2011

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Interactions between microorganisms shape microbial ecosystems. Systematic studies of mixed microbes in co-culture have revealed widespread potential for growth inhibition among marine heterotrophic bacteria, but similar synoptic studies have not been done with autotroph/heterotroph pairs, nor have precise descriptions of the temporal evolution of interactions been attempted in a high-throughput system. Here, we describe patterns in the outcome of pair-wise co-cultures between two ecologically distinct, yet closely related, strains of the marine cyanobacterium Prochlorococcus and hundreds of heterotrophic marine bacteria. Co-culture with the collection of heterotrophic strains influenced the growth of Prochlorococcus strain MIT9313 much more than that of strain MED4, reflected both in the number of different types of interactions and in the magnitude of the effect of co-culture on various culture parameters. Enhancing interactions, where the presence of heterotrophic bacteria caused Prochlorococcus to grow faster and reach a higher final culture chlorophyll fluorescence, were much more common than antagonistic ones, and for a selected number of cases were shown to be mediated by diffusible compounds. In contrast, for one case at least, temporary inhibition of Prochlorococcus MIT9313 appeared to require close cellular proximity. Bacterial strains whose 16S gene sequences differed by 1-2% tended to have similar effects on MIT9313, suggesting that the patterns of inhibition and enhancement in co-culture observed here are due to phylogenetically cohesive traits of these heterotrophs.

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Section: Prochlorococcus-heterotroph Interactions D Sher Et Almentioning

confidence: 93%

Response of Prochlorococcus ecotypes to co-culture with diverse marine bacteria

et al. 2011

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“…This peak is, however, centered at somewhat smaller diameters compared to bacteria in the infected samples (i.e., 800-900 nm, as opposed to about 1 mm). This result may be attributed to the fact that viruses rapidly adsorbed to bacterial cells in the infected culture, as well as to post-infection swelling of bacteria (Malfatti et al 2010). Overall, the stability of the PSD for the control sample lends confidence to the interpretation of our PSD and the optical results for the infected culture that they originated primarily from the viral infection of bacteria and consequent particle dynamics.…”

Section: Resultsmentioning

confidence: 59%

Variations in the optical properties of a particle suspension associated with viral infection of marine bacteria

Uitz¹,

Stramski²,

Baudoux³

et al. 2010

Limnology & Oceanography

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A laboratory experiment was conducted to examine the temporal dynamics of the particle size distribution (PSD) and associated optical variability caused by viral infection of marine heterotrophic bacteria. The PSD covering a broad range of particle size from < 50 nm to 200 mm was measured in parallel with the spectral particulate absorption and beam attenuation coefficients, from which the particulate scattering coefficient, b p (l), was determined. Within 12 h following infection, the host bacterial population collapsed, viral abundance increased, and submicron particles were produced as bacteria were disrupted and cell debris released, resulting in a large decrease in b p (l) seen as an almost complete clearing of the particle suspension. Throughout the remainder of the experiment, significant changes in the PSD occurred primarily within the size range of relatively large particles (. 4 mm), likely as a result of the aggregation of smaller-sized particles originating from the host lysis. The PSD data were used as input for Mie scattering calculations to evaluate the effects of these particle dynamics in terms of relative contributions of different particle size classes to the scattering and backscattering coefficients. This analysis showed a significant increase in the effect of particle aggregation on light scattering during the second and third days after infection. Viral lysis of bacteria and subsequent particle dynamics produce large variations in the PSD over a broad size range on timescales from hours to a few days, and such processes lead to correspondingly large changes in the suspension optical properties.

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“…The cell shapes ranged from bilobes to rods, with an average length of 1.46 m (SE, Ϯ0.039; n ϭ 100) and an average width of 0.59 m (SE, Ϯ0.0064; n ϭ 100). Size estimates were obtained using NanoOrange-staining cell-sizing methods (the ratios of DAPI to NanoOrange sizing were 0.87 and 0.78 for length and diameter, respectively) (44). The biovolume of PRT1, computed using the formula…”

Section: Resultsmentioning

confidence: 99%

“…After drying, the filter was mounted on a glass slide. Atomic force microscopy (AFM) imaging was performed with an MFP-3D BIO (Asylum Research, Santa Barbara, CA) as described by Malfatti et al (44). Briefly, images were acquired in AC mode in air with a silicon nitride cantilever (AC160TS; Olympus), with a spring constant of 42 N/m and scan rates of 1 Hz.…”

Section: Methodsmentioning

confidence: 99%

Isolation and Characterization of a Psychropiezophilic Alphaproteobacterium

Eloe

Malfatti

Gutierrez

et al. 2011

Appl Environ Microbiol

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Cultivated psychropiezophilic (low-temperature-and high-pressure-adapted) bacteria are currently restricted to phylogenetically narrow groupings capable of growth under nutrient-replete conditions, limiting current knowledge of the extant functional attributes and evolutionary constraints of diverse microorganisms inhabiting the cold, deep ocean. This study documents the isolation of a deep-sea bacterium following dilution-to-extinction cultivation using a natural seawater medium at high hydrostatic pressure and low temperature. To our knowledge, this isolate, designated PRT1, is the slowest-growing (minimal doubling time, 36 h) and lowest cell density-producing (maximal densities of 5.0 ؋ 10 6 cells ml ؊1 ) piezophile yet obtained. Optimal growth was at 80 MPa, correlating with the depth of capture (8,350 m), and 10°C, with average cell sizes of 1.46 m in length and 0.59 m in width. Through detailed growth studies, we provide further evidence for the temperature-pressure dependence of the growth rate for deep-ocean bacteria. PRT1 was phylogenetically placed within the Roseobacter clade, a bacterial lineage known for widespread geographic distribution and assorted lifestyle strategies in the marine environment. Additionally, the gene transfer agent (GTA) g5 capsid protein gene was amplified from PRT1, indicating a potential mechanism for increased genetic diversification through horizontal gene transfer within the hadopelagic environment. This study provides a phylogenetically novel isolate for future investigations of high-pressure adaptation, expands the known physiological traits of cultivated members of the Roseobacter lineage, and demonstrates the feasibility of cultivating novel microbial members from the deep ocean using natural seawater.High hydrostatic pressure is one of the most unique physical parameters in deep-ocean environments and plays a significant, albeit underappreciated, role in the distribution of life in the biosphere. The effects of high hydrostatic pressure on microbial physiology are pervasive, with influences ranging from macromolecular structures to diverse cellular processes such as cell division and motility (8).Studies of microbial assemblages from the abyssal (4,000 m to 6,000 m) and hadopelagic (Ͼ6,000 m) environments are riddled with methodological issues, including but not limited to (i) difficulty and expense of sample collection, (ii) bulk seawater collection that mechanically disrupts delicate colloidal and particulate microenvironments, and (iii) specialized high-pressure equipment to maintain samples at in situ pressure and temperature once shipboard (6, 51, 89). Intrinsic biological factors similarly compound the complications of sampling from depth, the most challenging of which is the mixing of allochthonous microbial members from the overlying surface seawater derived from the vertical transport of aggregated material.These "hitchhiking" microorganisms, which are not adapted to the prevailing conditions of the deep, render taxonomic cataloguing and diversity estimates o...

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High-resolution imaging of pelagic bacteria by Atomic Force Microscopy and implications for carbon cycling

Cited by 37 publications

References 56 publications

Response of Prochlorococcus ecotypes to co-culture with diverse marine bacteria

Response of Prochlorococcus ecotypes to co-culture with diverse marine bacteria

Variations in the optical properties of a particle suspension associated with viral infection of marine bacteria

Isolation and Characterization of a Psychropiezophilic Alphaproteobacterium

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