Diurnal cycles of sulfate reduction under oxic conditions in cyanobacterial mats

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Applied and Environmental Microbiology; (United States)

OSTI ID:5490318

Fruend, C ^[1]; Cohen, Y ^[2]

---

1. Interuniversity Inst. of Eilat (Israel)
2. Hebrew Univ., Jerusalem (Israel)

Diurnal cycles of sulfate reduction were examined in a well-developed cyanobacterial mat which grew in an outdoor experimental hypersaline pond system at a constant salinity of 75 {plus minus} 5% for 3 years. Vertical profiles of sulfate reduction were determined for the upper 12 mm of the microbial mat. Sulfate reduction activities were compared with diurnal variations of oxygen and sulfide concentrations measured by microelectrodes. Significant activity of sulfate-reducing bacteria was detected under aerobic conditions during the daytime, with maximal activity at 2 p.m. When comparing sulfate reduction activities in sediment cores taken at 6 a.m. and 12 a.m. and incubated at a constant temperature in the light and in the dark, a distinct stimulation of the activity in the vertical profile of sulfate reduction by light was evident. It is therefore concluded that the maximal in situ activities, measured at 2 p.m. in the chemocline of the cyanobacterial mat, cannot be attributed to diurnal changes of temperature alone. The response of sulfate-reducing bacteria to the addition of specific carbon sources was significantly different in the cyanobacterial layer, the anoxygenic phototrophic bacterial layer, and the permanently reduced layer of the microbial mat. Sulfate reduction in the mat layer exposed to high oxygen concentrations as a result of cyanobacterial oxygenic photosynthesis was enhanced only by glycolate; in the microzone where the chemocline is found during the daytime, ethanol was the only carbon source to enhance sulfate reduction, while both ethanol and lactate enhanced this activity in the permanently reduced zone.

• OSTI ID: 5490318
• Journal Information: Applied and Environmental Microbiology; (United States), Vol. 58:1; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
SULFATE-REDUCING BACTERIA
METABOLISM
SULFATES
REDUCTION
AEROBIC CONDITIONS
CYANOBACTERIA
DAILY VARIATIONS
ETHANOL
LACTIC ACID
SEDIMENTS
ALCOHOLS
BACTERIA
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
HYDROXY ACIDS
HYDROXY COMPOUNDS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SULFUR COMPOUNDS
VARIATIONS
540310* - Environment
Aquatic- Basic Studies- (1990-)
550700 - Microbiology