Isolation and characterization of a new reported cyanobacterium Leptolyngbya bijugata coproducing odorous geosmin and 2-methylisoborneol

Abstract

The earthy-musty compounds geosmin and 2-methylisoborneol (MIB) produced by cyanobacteria are considered as the main biological causes of off-flavor events, especially in aquatic ecosystems. More than 50 filamentous cyanobacteria species have been documented as geosmin or MIB producers; however, little is known about the species coproducing these two metabolites. In this study, an epiphytic sample was collected from a river in Hubei, China. Three isolated strains (A2, B2, and B4) producing earthy odors were successfully isolated and identified as the cyanobacterium Leptolyngbya bijugata Anagnostidis et Komárek 1988 based on morphology and 16S rDNA sequences. Gas chromatography analysis confirmed that the isolated L. bijugata strains were geosmin and MIB coproducers, with accumulation ranging from 13.6 to 22.4 and 12.3 to 57.5 μg L −1 , respectively. The partial fragments of geosmin and MIB synthesis genes in the L. bijugata strains were cloned and sequenced. Further sequences and phylogenetic analysis indicated the high conservation and a common origin of these genes in cyanobacteria. This study is the first to report and characterize the coproduction of geosmin and MIB by L. bijugata, representing a new source for potential risk of off-flavor events.

Diversity of the Potential 2-Methylisoborneol-Producing Genotypes in Thai Strains of Planktothricoides (Cyanobacteria)

“…Increasing eutrophication of water resources with changing climate are making cyanobacterial blooms more common, which can produce taste and odor episodes [1][2][3][4] . These undesirable effects are not only restricted to drinking water sources but are also significant causes of economic losses in the aquaculture industry due to their partitioning into fish flesh 5 .…”

“…dqh15 and P. raciborskii CHAB 3331 from China were confirmed to be 2-MIB producing organisms by using the 2-MIB synthesisassociated genes and GC-MS analyses. Afterwards, there were several cyanobacterial strains (e.g., Oscillatoria, Planktothrix and Letolyngbya bijugata) reported as the MIB producers 4,17 . These studies provided fundamental information for the development of molecular technologies to monitor odor-producing microorganisms and investigate the relationship between odor production and the corresponding synthesis genes.…”

“…However, no molecular technique for MIB-producing cyanobacteria has been established. Understanding the diversity of off-odor-producing groups is essential for the monitoring and management of off-flavor events 3,4,28,29 . Although off-odor has been described as a common problem for cultured fish, there are very few molecular genetic studies of cyanobacterial species producing off-odor from Thailand because of difficulties in the isolation and purification of strains.…”

Influence of Environmental Factors on the Production of MIB and Geosmin Metabolites by Bacteria in a Eutrophic Reservoir

“…also correlate with elevated phycocyanin signals in the late August samples (Figure ). From late August, occurrences of other Cyanobacteria such as the benthic Oscillatoria (Izaguirre et al, ; Suurnäkki et al, ) and potentially the epiphytic Leptolyngbya (Wang et al, ) may also have contributed to the production of GSM although individual contributions to the general background signal are often very difficult to assess (Juttner & Watson, ). Nonetheless, a few genera are found in more mixed (low RTRM) and turbid waters (high light extinction coefficients; k T ) with cooler temperatures.…”

The Chemistry, Biochemistry and Pharmacology of Marine Natural Products from Leptolyngbya, a Chemically Endowed Genus of Cyanobacteria

“…These simple terpenoids have each been reported numerous times as being among the main causes for off-flavors in water and other products [ 85 ]. Wang et al isolated 86 and 87 from Leptolyngbya bijugata strains, and quantified each at 13.6–22.4 and 12.3–57.5 μg/L, respectively, demonstrating their production by Leptolyngbya [ 86 ].…”