Korea Atomic Energy Research Institute

The environmental impacts of climate change highlight the need for sustainable bioprocesses using low-cost feedstocks. Microbial fermentation offers an eco-friendly method to produce value-added compounds from renewable resources. Deinoxanthin, a unique carotenoid pigment produced by radiation-resistant bacteria, Deinococcus, has pharmaceutical and food industry applications. However, most microorganisms preferentially utilize glucose as their primary carbon source, limiting their capacity to ferment byproducts or waste-derived resources effectively. Here, we hypothesized that identifying microbial hosts capable of metabolizing a broader range of nutrients could improve fermentation efficiency. Through whole-genome sequencing, we identified that D. yunweiensis KCTC3955 possesses multiple nutrient transporters and is capable of efficiently utilizing glycerol and various nitrogen sources for carotenoid production. Using one-factor-at-a-time and response surface methodologies, we optimized conditions with glycerol, achieving a 4.45-fold increase in carotenoid yield. Notably, key biosynthetic genes (dxr, idi, ispF, ispH, and cruF) were highly up-regulated under mixed nutrient conditions. Fed-batch fermentation with mixed renewable resources such as glycerol and corn steep liquor reached 23.22 mg/L carotenoid production and 15.48 mg/L/day productivity after 36 h, representing over 11- and 15-fold improvements compared to non-optimized conditions. These results highlight D. yunweiensis KCTC3955 as a strong candidate for carotenoid production from mixed renewable substrates.

Anal. methods for inorganic elements play a crucial role in archeometric investigations by revealing the technol. behind ancient ceramic production and the provenance of raw materials.In this study, a combination of nuclear- and at.-based anal. methods, including neutron activation anal., X-ray fluorescence spectroscopy, and Fourier-transform IR (FT-IR) spectroscopy, was applied to characterize ancient ceramic samples.These techniques provide comprehensive insights into the chem. composition, firing temperature, and color mechanisms, aiding archaeol. interpretation.Furthermore, the atm. conditions during the firing process were identified by determining the iron phases (Fe2O3, Fe3O4, and FeO) using the X-ray absorption near-edge structure spectroscopy, which proved to be more reliable than the previous FT-IR spectroscopy-based approaches.The integration of these anal. results provides an enhanced understanding of ancient ceramic production technologies.

The neopullulanase subfamily comprises diverse enzymes involved in starch modification. In Deinococcus radiodurans, we newly identified a maltogenic debranching amylase (DrMD) that lacks the N-terminal domain and uniquely exhibits both pullulanase (EC 3.2.1.41) and maltogenic amylase (EC 3.2.1.133, EC 3.2.1.54) activities at a single active site. Notably, DrMD produced a higher amount of reducing sugars from various types of gelatinized raw starch, showing a 4-fold increase in efficiency over type I pullulanase. The HPSEC-RI analysis indicated that DrMD hydrolyzes the branch point of the large amylopectin fraction, followed by the cleavage of the amylose structure. With side chain length-dependent debranching activity and maltogenic amylase-like function, DrMD was effective in producing glucose (G1) and maltooligosaccharides ranging from G2 to G5. As a result, 86.97% of the raw starch fraction was degraded into low-molecular-weight glucans (<1 × 10⁴ Da). These findings highlight efficiency of DrMD in starch modification and its potential as a versatile enzyme for industrial starch processing.