Plastic biodegradation by microorganisms is an eco-friendly and sustainable method without any ramifications. Herein, we used a cultivation method and 16S rRNA sequencing to screen bacteria that can efficiently colonize and degrade low-density polyethylene (LDPE) from various plastic wastes. We identified Bacillus safensis BS-10L through whole-genome sequencing analysis and verified its LDPE-degradation ability. However, the decomposition mechanism of the isolated bacteria was unclear and the decomposition efficiency was insufficient, so low-temperature plasma was used to increase the decomposition efficiency of the bacteria. The population and viability of bacteria treated with cold plasma increased. Plasma-activated bacteria could induce cracks, holes, and roughness on the surface of LDPE films over 90 days, and over 30 days; the LDPE film lost 13.40 ± 0.013% and 27.78 ± 0.014% of its mass by BS-10L and plasma-treated BS-10L, respectively. Fourier-transform infrared spectroscopic analysis identified new peaks of the C=O and C-O groups in the plasma-treated LDPE film, exhibiting high transmittance in the LDPE film that was inoculated with bacteria. X-ray photoelectron spectroscopic analysis showed that C-O bonds were generated by BS-10L strain, and relatively strong C=O bonds were generated in the film inoculated with plasma-treated BS-10L strain. Plasma treatment increased the colonization of the BS-10L strain and changed the chemical bonding of the LDPE film, suggesting that plasma-activated BS-10L could accelerate decomposition by oxidation by increasing the carbonyl group of the PE film. Therefore, plasma technology may be effective for enhancing the plastic-degrading ability of microorganisms.

The possibility of the activation of beneficial microorganisms using atmospheric plasma has rarely been examined. The application of plant growth-promoting bacteria (PGPB) as a microbial fertilizer to the field requires consistent efficiency. To overcome the limitations of PGPB as a microbial fertilizer, we investigated the potential of μ -dielectric barrier discharge plasma to increase the bacterial activity of a PGPB, Klebsiella pneumoniae , KW7-S06. Bacterial proliferation and vitality increased after plasma treatment. The infrared band of the observed Fourier transform infrared spectroscopy spectrum showed no change in the plasma-treated bacteria and untreated bacterial cell membranes. These results demonstrate that cells are not damaged by oxidative stress caused by plasma treatment. The density of bacteria adhering to the surface of rice seed inoculated with plasma-treated bacteria was higher than untreated bacteria. The germination rates of rice and barley seeds inoculated were significantly increased, and the growth of rice plants was also improved. The level of salicylic acid hormone was higher in rice plants infected with plasma-treated than with untreated bacteria. Our results demonstrated that plasma can accelerate bacterial growth and vitality, and the increased bacteria improved the adhesion of plant seed surfaces and elevated the level of phytohormones, leading to the enhancement of plant growth and tolerance to disease.

An effective and eco-friendly technology is needed to prevent postharvest loss of onion bulbs during cold storage. This study investigated the effect of gaseous ozone on the decay and quality of onion bulbs during storage at 2 °C and 70% relative humidity for two months. Gaseous ozone was adjusted to a concentration of 1.27 ± 0.024 ppm in the storage room by generating a high voltage discharge in air. After two months of storage, gaseous ozone significantly reduced the counts of aerobic bacteria (e.g., Rahnella aquatilis) and fungi (e.g., yeast and mold) in the onion bulbs by 4 log (CFU g⁻¹) and 0.92 log (CFU g⁻¹) compared with those of an untreated control, respectively. The microbial reduction by gaseous ozone resulted in a lower rotten rate of the onion bulbs, which was less than 20.0% compared with that of the untreated control. Moreover, the ozone exposure extended the storage life of the onion bulbs by delaying its color change and softening during storage. Our results suggest that gaseous ozone can control the decay of onion bulbs safely during storage.

We confirmed that micro dielectric barrier discharge plasma improved the growth and immunity of Panax ginseng C. A. Meyer seedlings. The growth rate of the ginseng seedlings was compared by height and weight monitoring. The length and weight of the aerial part of the 3 min. Plasma treated ginseng increased by 25% and 54%, respectively, compared to the untreated ginseng. The difference between the initial root weight before planting in the soil and the root weight 5 weeks after planting in the soil increased by 28% and 22% for the 3 and 10 min. Plasma treated ginseng, respectively. Chlorophyll and total phenolic contents were increased 62% and 56%, respectively in the aerial part of the plasma-treated ginseng seedlings compared to the untreated controls. Radical scavenging activity was also increased by 18% in the 3 min plasma treated ginseng seedlings. The plasma treatment increased the expression level of chlorophyll metabolism-related and auxin response factor genes in ginseng and might be the result of ginseng growth development by enhancing plant growth hormone. Increasing disease resistance through induced systemic resistance can ultimately improve crop productivity by strengthening the immune system. We demonstrated this by comparing the transcription patterns of genes involved in the pathogenic defense mechanisms of ginseng. The expression of the pathogen-associated PgPR2, PgPR5, PgPR10 and PgCAT genes improved significantly and rapidly in the plasma treated ginseng seedlings. In particular, mRNA expression levels of the PgPR2 and PgPR5 genes were significantly increased 5- and 3-fold, respectively, in the 10 min plasma treated seedlings. An increased expression level of abscisic acid signaling related genes ( PgABF and PgPYL ) means an increased resistance to stress, which in turn, could affect the enhanced antioxidant activity. Our results suggest that plasma can enhance the growth and increase the immunity of ginseng seedlings especially by improving its resistance to pathogens. Effective control of diseases using plasma technology could be one of the biggest factors that increase the yield of perennial medicinal plants such as ginseng.

Plant-derived substances exhibit antioxidant and antibacterial activities and have been proven to have beneficial effects in wound healing and skin regeneration. Plant stem cells have recently received much attention as research materials in cosmetic development because they promote regeneration after damage. In this paper, we demonstrate for the first time that the plasma treatment of stem cells obtained from rice-seed embryos can be effective in enhancing antioxidant activity and in regenerating human skin. We investigated this potential utilizing micro-DBD (Dielectric Barrier Discharge) plasma as a pretreatment technique to enhance the vitality and functional activity of rice stem cells. The results of the cell culture experiments show that plasma-treated rice stem cell extracts (RSCE) have promising antioxidant and anti-skin aging activities. The results of quantitative real-time PCR (qRT-PCR) for major antioxidant enzymes and anti-aging genes confirm that the plasma technique used in the pretreatment of RSCE was able to enhance cell activities in skin regeneration, including cell survival, proliferation, and collagen enhancement for Human Fibroblast (HFB) degraded by oxidative stress. These results show that the relatively low energy of less than 300 W and an amount of NOx-based reactive nitrogen species (RNS) from plasma discharge of about 3 μL/L were the key factors and that RSCE, of which the antioxidant activity was enhanced by plasma treatment, appeared to be a major contributor to the protective effect of HFB against oxidative stress. Plasma-treated RSCE induced excellent anti-aging properties by stimulating HFB to promote collagen synthesis, thereby promoting skin regeneration. These properties can protect the skin from various oxidative stresses. This study demonstrates that plasma-treated extracts of stem cells derived from rice-seed embryos have an excellent regenerative effect on aging-treated HFB. Our results demonstrate the potential utility of plasma-treated RSCE as a skin anti-aging agent in cosmeceutical formulations for the first time.