Bactericidal efficacy of non-thermal plasma activation against Aeromonas hydrophila and immunological responses of koi (Cyprinus carpio haematopterus).

In the aquaculture industry, an efficient and safe water purification system is important to prevent mass mortality by virulent pathogens. As extensive use of traditional methods (e.g.: povidone-iodine, ozone, ultraviolet irradiation, formalin, and chlorine dioxide) have adverse effects on cultured fish, an appropriate and alternative water purification method is vital for the sustainability of the industry. Non-thermal plasma technology has been successfully used for various biomedical purposes (e.g: food sterilization, medical device disinfection, wound healing, cancer therapy, etc.) and has great potential to be used as a sterilizing system. However, few studies have been conducted on its usefulness in the aquaculture industry. In this study, we investigated the bactericidal efficacy of plasma-activated water induced by non-thermal plasma and its histopathological as well as immunological adverse effects on koi. A highly virulent Aeromonas hydrophila SNU HS7, which caused massive mortality of koi, was used for this study. Non-thermal plasma was applied for 10 min to the fish tanks with 1.2 × 109 CFU/mL SNU HS7 using PLMB-20 system to confirm the sterilization efficacy and to observe the survival and immunological reaction of koi for 14 days. As a result, gross pathological, histopathological, and immunological investigations did not reveal any significant adverse effects in fish as compared to the control groups. To the best of our knowledge, this is the first study showing that non-thermal plasma can be used for sterilization of rearing water without giving significant physiological damage to the fish, even under the assumption of extreme situations. As plasma can effectively sterilize not only bacteria but also other unknown pathogens, the results of this study are showing a promising future in purifying water in aquaculture practice.

Characterization, metabolites and gas formation of fumarate reducing bacteria isolated from Korean native goat (Capra hircus coreanae).

Fumarate reducing bacteria, able to convert fumarate to succinate, are possible to use for the methane reduction in rumen because they can compete for H(2) with methanogens. In this, we isolated fumarate reducing bacteria from a rumen of Korean native goat and characterized their molecular properties [fumarate reductase A gene (frdA)], fumarate reductase activities, and productions of volatile fatty acids and gas. Eight fumarate reducing bacteria belonging to Firmicutes were isolated from rumen fluid samples of slaughtered Korean black goats and characterized their phylogenetic positions based on 16S rRNA gene sequences. PCR based analyses showed that only one strain, closely related to Mitsuokella jalaludinii, harbored frdA. The growths of M. jalaludinii and Veillonella parvula strains were tested for different media. Interestingly, M. jalaludinii grew very well in the presence of hydrogen alone, while V. parvula grew well in response of fumarate and fumarate plus hydrogen. M. jalaludinii produced higher levels of lactate (P≤0.05) than did V. parvula. Additionally, M. jalaludinii produced acetate, but not butyrate, whereas V. parvula produced butyrate, not acetate. The fumarate reductase activities of M. jalaludinii and V. parvula were 16.8 ± 0.34 and 16.9 ± 1.21 mmol NADH oxidized/min/mg of cellular N, respectively. In conclusion, this showed that M. jalaludinii can be used as an efficient methane reducing agent in rumen.

Highly selective CO2 capture on N-doped carbon produced by chemical activation of polypyrrole functionalized graphene sheets.

N-doped porous carbon produced via chemical activation of polypyrrole functionalized graphene sheets shows selective adsorption of CO(2) (4.3 mmol g(-1)) over N(2) (0.27 mmol g(-1)) at 298 K. The potential for large scale production and facile regeneration makes this material useful for industrial applications.