Geosmin and 2-methylisoborneol production in a major aqueduct system

Abstract

The California Aqueduct supplies water from Northern California to Southern California, dividing into the West and East branches above Pyramid Lake. In July and August 1990, elevated geosmin levels (10-48 ng/l) occurred in the East Branch of the aqueduct, which extends along the southern edge of the Mojave Desert. The geosmin episode was associated with attached algal growths on the sides of the aqueduct. A geosmin-producing cyanobacterium, possibly a Microcoleus sp., was isolated from both water and periphyton. In the summer of 1991, elevated levels of 2-methylisoborneol (MIB) occurred in the East Branch of the aqueduct (up to 78 ng/l), along with lower levels of geosmin. In July 1992, a recurrence of MIB production led to a severe off-flavor problem for a water agency that receives water directly from the aqueduct, resulting in numerous complaints from consumers. In both episodes, a Lyngbya sp. was isolated from periphyton and mud collected near the water's edge. These isolates were strong MIB producers in culture, yielding 240 and 260 μg/l, respectively. Beginning in 1992, a second, relatively weak MIB producer, a Hyella sp., was isolated from membrane-filter plates inoculated with aqueduct water. These off-flavor episodes - associated with low flows during a drought period - showed that previously untainted water sources can be affected by these problems when conditions change.

Contribution of Streptomyces in sediment to earthy odor in the overlying water in Xionghe Reservoir, China

“…Many reports have determined that benthic-dwelling cyanobacteria are associated with the occurrence of musty odor (Vilalta et w a t e r r e s e a r c h 4 4 ( 2 0 1 0 ) 6 0 8 5 e6 0 9 4 Izaguirre and Taylor, 1995). In Xionghe Reservoir, the abundance of the diatoms reaches 94% among all benthic algae, with Cyclotella, Synedra and Melosira as dominant genus.…”

Terpene synthases are widely distributed in bacteria

“…1) are well-known as volatile odoriferous microbial metabolites. The two terpene alcohols are, in fact, the most frequently found secondary metabolites in actinomycetes (8,11,17), filamentous Cyanobacteria (18)(19)(20), and Myxobacteria (21), and they are also produced by a small number of fungi (22)(23)(24). The production of 2-methylisoborneol is associated with a characteristic scent, whereas albaflavenone, which was first isolated from cultures of a highly odoriferous Streptomyces albidoflavus species, is best described as earthy and camphor-like (25).…”

2-methylisoborneol and geosmin, the main sources of soil odor, inhibit the germination of brassicaceae seeds

“…MIB and geosmin are detected by the human olfactory system at concentrations as low as several parts per billion (Izaguirre et al 1982) and by various kinds offish (Tosi and Sola 1993;Kawamura et al 1995), suggesting that chemical sensing of these microbial metabolites has been conserved during evolution and is beneficial to survival in various environments. In other words, MIB and geosmin may have been playing an important role in the ecosystems.…”