Effect of Rainfall and pH on Musty Odor Produced in the Sanbe Reservoir

Harmful cyanobacterial blooms are continuously formed in water systems such as reservoirs and lakes around the world. Geosmin and 2-methylisoborneol (2-MIB) produced by some species of cyanobacteria have caused odor problems in the drinking water of the Sanbe Reservoir in Japan. Field observations were conducted for four years (2015–2019) to investigate the cause of this musty odor. It was found that geosmin was produced by Dolichospermum crassum and Dolichospermum planctonicum (cyanobacteria), and 2-MIB was due to Pseudanabaena sp. and Aphanizomenon cf. flos-aquae (cyanobacteria). Changes in water temperature and pH caused by rainfall were correlated with changes in the concentration of geosmin and 2-MIB. In particular, geosmin and 2-MIB tended to occur under low rainfall conditions. When there was low rainfall, the reservoir changed to an alkaline state because the phytoplankton consumed CO2 for photosynthesis. In an alkaline reservoir, dissolved inorganic carbon mainly existed in the form of bicarbonate (HCO3−). Thus, the results suggest that under such conditions in reservoirs, cyanobacteria grew easily because they could use both CO2 and HCO3− for photosynthesis. Specifically, our study suggests that in order for the musty odor problem in the reservoir to be solved, it is important that the pH of the reservoir be controlled.

B. vulgaris ssp. vulgaris Chromosome 8 shows significant association with geosmin concentration in table beet

Geosmin, a degraded sesquiterpene molecule with earthy and musty odor, imbues table beet with its characteristic aroma. Geosmin is heritable and endogenously produced in table beet; its earthy aroma is sought by some consumers but deters others. Geosmin biosynthesis is catalyzed by a bifunctional geosmin synthase enzyme in diverse bacteria and fungi, but a mechanism for geosmin biosynthesis in plants has not been reported. This work employed association analysis and selective genotyping of a segregating F2:3 mapping population to seek QTL associated with geosmin concentration in table beet. GBS reads were aligned to sugar beet reference genome EL10.2, and association analysis revealed two QTL for geosmin concentration on B. vulgaris ssp. vulgaris Chromosome 8. QTL at EL10.2 positions 28,017,624 and 38,488,687 each show effect size 8.7 μg · kg-1 geosmin and explain 8.5% and 6.4% of total variation in geosmin concentration, respectively. Resolution was low due to large recombination bin size and imperfect alignment between the reference genome and mapping population, but population size and selection proportion were sufficient to detect moderate to large effect QTL. This study, the first molecular genetic mapping experiment in table beet, succeeded in finding QTL for geosmin concentration in table beet, and it provides the basis for fine mapping or candidate gene investigation of functional loci for this distinctive sensory trait.

A noncoding RNA modulator potentiates phenylalanine metabolism in mice

The functional role of long noncoding RNAs (lncRNAs) in inherited metabolic disorders, including phenylketonuria (PKU), is unknown. Here, we demonstrate that the mouse lncRNA Pair and human HULC associate with phenylalanine hydroxylase (PAH). Pair-knockout mice exhibited excessive blood phenylalanine (Phe), musty odor, hypopigmentation, growth retardation, and progressive neurological symptoms including seizures, which faithfully models human PKU. HULC depletion led to reduced PAH enzymatic activities in human induced pluripotent stem cell–differentiated hepatocytes. Mechanistically, HULC modulated the enzymatic activities of PAH by facilitating PAH-substrate and PAH-cofactor interactions. To develop a therapeutic strategy for restoring liver lncRNAs, we designed GalNAc-tagged lncRNA mimics that exhibit liver enrichment. Treatment with GalNAc-HULC mimics reduced excessive Phe in Pair−/− and PahR408W/R408W mice and improved the Phe tolerance of these mice.

Effect of Rainfall and pH on Musty Odor Produced in the Sanbe Reservoir

Harmful cyanobacterial blooms (HCBs) are continuously formed in water systems such as reservoirs and lakes around the world. In particular, geosmin and 2-methylisoborneol (2-MIB), which are made by cyanobacteria, have caused serious musty-odor problems in the drinking water of the Sanbe reservoir in Japan. To investigate the cause of this musty odor, we conducted field observations for five years (2015–2019). As a result, it was determined that the geosmin was caused by the cyanobacteria as Dolichospermum crassum and Dolichospermum planctonicum, and 2-MIB was caused by the cyanobacteria as Pseudanabaena sp and Aphanizomenon cf. flos-aquae. It was also determined that the occurrence of geosmin and 2-MIB are influenced by changes in water temperature and pH due to the inflow of rainfall. Especially, the geosmin and 2-MIB tended to occur in low rainfall conditions. When there is low rainfall, the reservoir changes to an alkaline state due to the consumption of CO2 by the photosynthesis of phytoplankton. In an alkaline reservoir, CO2 exists in the form of bicarbonate (HCO3-); thus, under these condition cyanobacteria will increase because it uses both CO2 and bicarbonate (HCO3-) for photosynthesis. Our study suggests that for solving the musty-odor problem in the reservoir, it is important to control the reservoir’s pH. Moreover, more focus should be place in managing the water quality problem of the Sanbe Reservoir, especially, during low rainfall years. The results of this study will help in addressing odor related water quality problem in other reservoirs.

Increased electrode activity during geosmin oxidation provided by Pt nanoparticle-embedded nanocarbon film

The musty odor compound geosmin was electrochemically detected by using Pt nanoparticle (PtNP)-embedded nanocarbon (Pt–C) films formed with unbalanced magnetron (UBM) co-sputtering.