Isolation of Aspergillus oryzae mutants producing low levels of 2,4,6-trichloroanisole.

Musty or moldy off-odor in sake severely reduces its quality. Such off-odor is caused by 2,4,6-trichloroanisole (TCA), a compound that is produced by Aspergillus oryzae during sake production by O-methylating the precursor 2,4,6-trichlorophenol (TCP). TCP suppresses the growth of fungi, including A. oryzae, although TCA does not. Therefore, strains that are unable to convert TCP to TCA should be sensitive to TCP in the medium. Nevertheless, A. oryzae with a disrupted O-methyltransferase gene (ΔomtT) grew in a medium containing TCP. In agar medium, we observed no growth difference between the ΔomtT strain and a non-disrupted transformant; however, a significant growth delay was observed with the ΔomtT strain grown in liquid medium containing 0.5 µg/mL of TCP. This strain was more sensitive to low concentrations of TCP, suggesting that omtT contributes to the conversion (detoxification) of TCP in liquid culture. We generated A. oryzae RIB 40 mutants by ultraviolet irradiation and then cultured them in liquid medium containing TCP to obtain strains that did not produce moldy odor. The slow-growing strains were cultured in agar plates and then used to make koji with added TCP. We obtained three strains with lower TCA-producing ability and with sufficient hydrolase activities for sake brewing.

Long-Term Decreased Exercise Capacity of COVID-19 Patients Who Received Mechanical Ventilation in Japan: A Case Series.

ABSTRACT: The long-term exercise capacity of coronavirus disease 2019 patients with acute respiratory distress syndrome is not clear. The 6-min walking distance of four patients with coronavirus disease 2019-associated acute respiratory distress syndrome was followed for 6 mos after admission to the hospital. These four patients were admitted to the intensive care unit of our hospital and received mechanical ventilation. Rehabilitation therapy (positioning, postural drainage, and passive range-of-motion exercises) was started after intensive care unit admission. Mobilization therapy, including muscle power training, sitting on the edge of the bed, and endurance training, was performed after the end of sedation. The Medical Research Council sum scores and Barthel Indexes for the patients improved after intensive care unit discharge and completely recovered 6 mos after admission to the hospital. However, the 6-min walking distance of the four patients remained shorter than those of healthy persons of the same age at 6 mos after admission to the hospital. Furthermore, the minimum Spo2 during the 6-min walking test remained less than 96%. It is possible that patients who receive mechanical ventilation due to coronavirus disease 2019-associated acute respiratory distress syndrome have decreased long-term exercise capacity, despite muscle power and activities of daily living recovering completely.