Distribution of microaerophilic bacteria through the oxic-anoxic transition zone of lagoon sediments

Abstract

In marine sediments, where soluble gases diffuse only very slightly, many organisms struggle for molecular oxygen. Microaerophilic bacteria, able to grow at reduced p0, between 0.2 and 12 %, have an advantage. Distribution of aerobes, microaerophiles and anaerobes was compared with the oxygen gradient in seawater and sediment samples collected in a northern Mediterranean lagoon. In the near bottom seawater and in the O-10 mm upperlayer of sediment, the microaerophilic counts were less than 1 y0 of aerobe densities. In the lo-15 mm zone, these two groups were equivalent in density (1 x lo5 cells ml-'). As expected, the microaerophiles took advantage of their low oxygen tension requirements in the subsurface sediments, between the well aerated zone (O-5 mm depth) and the low redox potential zone. Then, beyond a depth of 20 mm, the anaerobes prevailed in this sandy clay.

Seasonal and inter-annual variation of bacteria in a seagrass bed of the Mediterranean Sea: relationship with labile organic compounds and other environmental factors

“…Significance of bacteria in the seagrass system Bacterial densities in Prelo Bay were high when compared to other coastal areas (De Flaun & Mayer 1983, Meyer-Reil 1983, Montagna et al 1983, Herndl et al 1989, Delille et al 1990, Ferrara-Guerrero & Bianchi 1990, Amon & Herndl 1991, Albertelli et al 1992 and bacterial biomass was a significant fraction (on average 6.23 %) of the sedimentary organic carbon. This value appears to be similar to those reported for deep-sea sediments (on average 9.5 %; ) but high if compared to other areas of the Ligurian Sea (3.5%; Fabiano .…”

Microaerophilic bacterial biomass measurements based on Adenosine Triphosphate and direct counting techniques in a semi-solid agar column

“…deeper levels in the tube (Ferrara-Guerrero and Bianchi, 1990). As a result, the bacterial growth appears in the form of well-defined layers at different depths in the agar column, according to their oxygen requirements.…”

“…Bacterial biomass is regarded as one of the most important ecological parameters for evaluating the productivity of aquatic environments. Microbial ecosystems with aerobic and anaerobic zones are found in sediments (Jones, 1982;Revsbech and Jørgensen, 1986;Anderson and Helder, 1987;Ferrara-Guerrero and Bianchi, 1990), soils (Smith and Arah, 1986;Reddy et al, 1989;Skopp et al, 1990;Focht, 1992), stratified water columns (Karl, 1982;Jones, 1987;McDonough et al, 1986;Millero and Sohn, 1992;Wynn-Williams, 1992) and microbial biofilms (Nielsen et al, 1990). Strict aerobes depend upon molecular oxygen for their metabolism and strict anaerobes can only grow in an oxygen-free environment, whereas microaerophiles depend on molecular oxygen but in concentrations from 0.2% to 12% (Bowdre et al, 1976).…”

Variation of a benthic heterotrophic bacteria community with different respiratory metabolisms in Coyuca de Benítez coastal lagoon (Guerrero, Mexico)

“…Also, increased eutrophication of coastal regions has led to frequent formation of suboxic/anoxic water masses in which anaerobic metabolism replaces aerobic metabolism in microbial communities (Sherr and Sherr 2000). Most studies realized on the bacterial distribution according to the concentration of dissolved oxygen in aquatic environments were done on the water column samples, but little is known about these processes on sediments owing to the technical difficulties that this implies (Jørgensen and Revsbech 1985, Daumas 1989, Ferrara-Guerrero and Bianchi 1990, Cammen 1991, Rasmussen and Jørgensen 1992, Roden and Tuttle 1992.No studies about the bacterial trophic state in the Coyuca de Benitez lagoon (Guerrero, Mexico) are available; therefore the present work was done with the main purpose to study of in situ spatial fluctuations of the heterotrophic bacteriobenthos, in a short scale of time in relation to the physical and chemical changes in the environment. …”