ABSTRACT
The advancement of regenerative life support systems (RLSS) is crucial to allow long-distance space travel. Within the Micro-Ecological Life Support System Alternative (MELiSSA), efficient nitrogen recovery from urine and other waste streams is vital to produce liquid fertilizer to feed food and oxygen production in subsequent photoautotrophic processes. This study explores the effects of ionizing radiation on nitrogen cycle bacteria that transform urea to nitrate. In particular, we assess the radiotolerance of Comamonas testosteroni, Nitrosomonas europaea, and Nitrobacter winogradskyi after exposure to acute γ-irradiation. Moreover, a comprehensive whole transcriptome analysis elucidates the effects of spaceflight-analogue low-dose ionizing radiation on the individual axenic strains and on their synthetic community o. This research sheds light on how the spaceflight environment could affect ureolysis and nitrification processes from a transcriptomic perspective.
ABSTRACT
Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.
ABSTRACT
Lack of proper hand hygiene among healthcare workers has been identified as a core facilitator of hospital-acquired infections. Although the concept of hand hygiene quality assurance was introduced to Vietnam relatively recently, it has now become a national focus in an effort to improve the quality of care. Nonetheless, barriers such as resources, lack of education, and cultural norms may be limiting factors for this concept to be properly practiced. Our study aimed to assess the knowledge and attitude of healthcare workers toward hand hygiene and to identify barriers to compliance, as per the World Health Organization's guidelines, through surveys at a large medical center in Vietnam. In addition, we aimed to evaluate the compliance rate across different hospital departments and the roles of healthcare workers through direct observation. Results showed that, in general, healthcare workers had good knowledge of hand hygiene guidelines, but not all believed in receiving reminders from patients. The barriers to compliance were identified as: limited resources, patient overcrowding, shortage of staff, allergic reactions to hand sanitizers, and lack of awareness. The overall compliance was 31%; physicians had the lowest rate of compliance at 15%, while nurses had the highest rate at 39%; internal medicine had the lowest rate at 16%, while the intensive care unit had the highest rate at 40%. In summary, it appears that addressing cultural attitudes in addition to enforcing repetitive quality assurance and assessment programs are needed to ensure adherence to safe hand washing.
