Effect of CO and light on ammonium and nitrite oxidation by chemolithotrophic bacteria

Abstract

The effects of CO and light on the ammonium oxidizing bacterium Nitrosomonas cryotolerans and the nitrite oxidizing bacterium N~trobacter sp Nb297 were investigated. Ammonium oxldahon was inhibited by C O concentrations ranging from 2 n M to 11.4 FM. CO inhibition was cell density dependent and increased if the cells had been either previously starved or deprived of iron. Ammonium oxidation was inhibited by 63 % at intensities a s low a s 5 W m-2 of artificial light. Nitrobactersp. Nb297, on the other hand, was able to tolerate C O concentrations as high as 400 PM. Artificial light (25 W m-*) slightly reduced nitrite oxidation while sunlight (628 W m-') decreased activity to ca 20 % of its original value. In addition, C O and CH, oxidation by N. cryotolerans and natural assemblages of bacteria were inhibited by light. It is apparent from these studies that the mechanisms of light and C O inhibition are different for the NH: and NO; oxidizers examined. Characterization of light and C O responses by marine nitrifying bacteria is critical in any attempt to explain the formation of the subsurface primary nitrite maximum.

Origin, causes and effects of increased nitrite concentrations in aquatic environments

“…Olson (1981) and Vanzella et al (1989) found evidence that NOB were more sensitive to sunlight than AOB. In coastal marine samples, Olson (1981) found a 50% inhibition of nitrite oxidation at a light intensity of 6.64 µmol m −2 s −1 , as opposed to a 50% inhibition of ammonia oxidation at light intensity of 18.26 µmol m −2 s −1 (full sunlight = 2490 µmol m −2 s −1 ).…”

Enzyme‐level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean

“…As the mixed layer deepens into the fall and erodes into the underlying T min layer, where nitrifiers have presumably been active during the summer, some of these nitrifiers may be entrained from the T min layer into the fall surface ocean. Upon exposure to elevated levels of light or other new conditions, the NO 2 À oxidizers may slow their activity, such that the unidirectional oxidation of NO 2 À to NO 3 À is reduced [Vanzella et al, 1989]. Under these conditions, the bifunctional NXR enzyme may catalyze both the forward and back reactions, yielding the isotopic distribution expected from NO 3 À -NO 2 À interconversion ( Figure 6).…”

“…Nitrifier activity has been found to be inhibited by light [Vanzella et al, 1989;Guerrero and Jones, 1996], although it may not be Global Biogeochemical Cycles…”

Recovery of nitrification in marine bacteria following exposure to carbon monoxide or light

“…Bottles were sealed with silicon rubber stoppers and incubated in the dark on a rotatory shaker (150 rpm) at 25°C for up to 24 h. At different time intervals 25 m1 samples were removed from each bottle and assayed for nitrite production as an index of ammonium oxidation (Bendschnetder & Robinson 1952) Recovery of Nitrobacter sp. from CO was not examined since these organisms were not significantly inhibited by any of the CO concentrat~ons previously tested (Vanzella et al 1989).…”

“…Cycling of Instant Ocean Synthetic Sea Salts (Aquarium Systems, nitrogen in the surface waters of the sea may therefore Inc., Mentor, Ohio; Jones & Hood 1980). Nitrite oxidizdepend upon the ability of these organisms to recover ers were cultured in the same manner in the medium of from light and CO. Vanzella et al (1989) showed that Watson & Waterbury (1971). The concentration of NO2-high substrate concentration benefits actively growing as N a N 0 2 was 0.029 M. Cultures were vigorously aermarine nitrifiers since it increased their tolerance to ated, agitated by a magnetic stirring bar, and kept at a these inhibitors.…”