The nitrogen cycle is a biogeochemical cycle primarily associated with the microbial activity that occurs in various environments, including soil. Various genes related to the nitrogen cycle have been studied for different purposes by many researchers; therefore, the polymerase chain reaction (PCR) conditions and gene compositions differ among reports, making comparisons difficult. In this study, we compare the PCR methods to amplify 13 nitrogen cycle-related genes (amo (amoA and amoB), norB (cnorB and qnorB), hzs, napA, narG, nifH, nirK, nirS, nosZ, nrfA, and nxrA) in the soil samples collected from four land use types and selected a method with excellent applicability. However, the PCR method for five nitrogen cycle-related genes (amoC, hao, hzo, nirB, and nxrB) could not be presented. In addition, the nitrogen cycle-related genes from the four land use types (field, forest, bare land, and grassland) and the seasonally collected samples were analyzed and discussed. In the grassland samples, all the nitrogen cycle-related genes reviewed were amplified. These results vary from those of the field, forest, and bare land samples, and it was estimated that grassland, among the land use types, could play an important role in the nitrogen cycle in soil. However, an association between the seasons and the rainy season was not confirmed. Thus, this study may be used for future research in various fields related to the nitrogen cycle.

Soil has multiple functions, including the provision of habitat to organisms, and most biological activities occur in the surface soil. Due to the negative effects of soil erosion, efforts for soil conservation are being made, including the development of a reliable index that can help assess soil quality. In this study, the physical and chemical properties and biological genes from grassland topsoil were analyzed, in order to identify surface soil organism markers that could be used as a soil quality index. Six spots of grassland topsoil were analyzed, one high-quality and five low-quality, based on a web-based soil quality assessment module. Consequently, eukaryotes and prokaryotes with different soil quality ratios were compared and examined. The following bacteria and archaea have the potential to be used in soil quality assessment: circulation of materials including nitrogen, Nitrospira spp., Candidatus Nitrososphaera, and Candidatus Nitrosotalea; biological purification, Geobacter spp.; pathogens, Burkholderia spp., Paraburkholderia spp., Pseudomonas brassicacearum, and Rhizobacter spp.; antibiotic secretion, Candidatus Udaeobacter; and material degradation Steroidobacter spp. and Rhodanobacter spp. This study provides primary data for identifying biological markers for soil quality evaluation. In the future, a wider variety of data need to be accumulated to develop a highly reliable index related to soil quality.

The African swine fever virus (ASFV) causes severe disease in wild and domestic pigs, with high mortality rates, extensive spread, and significant economic losses globally. Despite ongoing efforts, an effective vaccine remains elusive. Therefore, effective diagnostic methods are needed to rapidly detect and prevent the further spread of ASF. This study assessed nine commercial kits based on real-time polymerase chain reaction (PCR) approved in the Republic of Korea using the synthesized ASFV plasmid, 20 food waste samples, and artificially spiked samples (ASSs). The kits were evaluated for their diagnostic sensitivity, specificity, cost per reaction, and reaction running time. In addition, the results were compared with those of the World Organization for Animal Health (WOAH) standard methods. Three commercial kits (VDx^® ASFV qPCR Kit, Palm PCR™ ASFV Fast PCR Kit, and PowerChek™ ASFV Real-time PCR Detection Kit Ver.1.0) demonstrated the highest sensitivity (100 ag/μL), cost-effectiveness (less than KRW 10,000), and shortest running time (less than 70 min). These kits are suitable for the monitoring, early diagnosis, and prevention of the spread of ASF. This is the first report on the performance comparison of ASFV diagnostic kits approved in the Republic of Korea, providing valuable information for selecting kits for testing with food waste samples.

Hepatitis E virus (HEV) is a leading cause of acute viral hepatitis and is primarily transmitted via contaminated water and food. Groundwater may also serve as a potential vector for HEV transmission. This study aimed to optimize real-time polymerase chain reaction (rtPCR) for the detection of HEV, employing both TaqMan probe- and SYBR Green-based methods. A total of 12 primer sets for the TaqMan probe-based method and 41 primer sets for the SYBR Green-based method were evaluated in order to identify the optimal combinations. Primer sets #4 (TaqMan probe-based) and #21 (SYBR Green-based) demonstrated the highest sensitivity and specificity, successfully detecting HEV in artificially spiked samples at 1 fg/μL. The TaqMan probe-based method facilitated rapid detection with minimized non-specific amplification, whereas the SYBR Green-based method allowed for broader primer exploration by leveraging melting curve analysis. Despite the absence of HEV detection in 123 groundwater samples, this study underscores the value of real-time PCR for environmental monitoring and paves the way for enhanced diagnostic tools for public health applications.