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

Abstract

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.

Interpreting LISST‐100X measurements of particles with complex shape using digital in‐line holography

“…It seems even more counter‐intuitive, therefore, that during our deployments the LISST‐100X reported a consistent fine tail, especially given the dynamism of in‐situ size distributions. Given the discrepancy between in‐situ imaging and LISST‐100X size distributions, and the similarity between LISST‐100X and distributions derived in the laboratory [e.g., Reynolds et al , 2010; Uitz et al , 2010], it seems that sample handling, preparation and the choice of analysis method itself (e.g., flow cytometery, optical microscope) cause significant discrepancies between instrumentation in most inter‐comparisons [see, e.g., Serra et al , 2001]. Caution against over‐interpretation of laboratory‐derived size distributions ought to be exercised.…”

“…Increasing error in laser diffraction measurements has also been noted by Reynolds et al [2010] for particle populations with poor sorting. Interestingly, Ahn and Grant [2007] observed that chemical and mechanical disaggregation of samples prior to analysis improved the agreement between LISST and optical microscopy and both Reynolds et al [2010] and Uitz et al [2010] have show almost 1:1 agreement in particle concentration and size between LISST and Coulter counter measurements for fine particles.…”

Measurements of the Volume Scattering Function and the Degree of Linear Polarization of Light Scattered by Contrasting Natural Assemblages of Marine Particles

“…For example, the scattering and backscattering coefficients of suspended particles have been shown to provide useful proxies of mass concentration of total suspended particulate matter (SPM), particulate inorganic carbon (PIC), and particulate organic carbon (POC) in the ocean [5][6][7]. Multi-angle light scattering measurements provide a means to estimate the particle size distribution [8][9][10][11], including the submicrometer size range [12][13][14]. The angular pattern of light scattering can also contain useful information about the composition of particulate assemblages, including the bulk refractive index of particles [15][16][17][18][19].…”

The structure of natural microbial enemy-victim networks

“…Quantifying the temporal dynamics of phage impact and untangling the underlying ecological and evolutionary causal mechanisms could yield interesting insights but is beyond the scope of the present study. The resolution of our OD measures (Uitz et al 2010;Zwietering et al 1990) permits the detection of weak links, which is not always possible in other types of association, namely those that depend upon field sampling or the direct observation of rare interactions (Goldwasser and Roughgarden 1997;Olesen and Jordano 2002). Our bacteria-phage networks can be accessed online (http://dx.doi.org/10.6084/m9.…”