• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.5
• /
• pp.839-846
• /
• 2016

Since oil leakage is one of the most common nonpoint pollution sources that contaminate soil in Korea, the capacity of soil microbial community for degrading petroleum hydrocarbons should be considered to assess the functional value of soil resource. However, conventional methods (e.g., microcosm experiments) to assess the remediation capacity of soil microbial community are costly and time-consuming to cover large area. The present study suggests a new approach to assess the toluene remediation capacity of soil microbial community using a microbial diversity index, which is a simpler detection method than measuring degradation rate. The results showed that Shannon index of microbial community were correlated with specific degradation rate ($V_{max}$), a degradation factor. Subsequently, a correlation equation was generated and applied to Michaelis-Menten kinetics. These results will be useful to conveniently assess the remediation capacity of soil microbial community and can be widely applied to diverse engineering fields including environment-friendly construction engineering fields.

• Journal of Microbiology
• /
• v.42 no.2
• /
• pp.160-162
• /
• 2004

Rhodococcus sp. strain T104 is able to utilize both limonene and biphenyl as growth substrates. Fur-thermore, T104 possesses separate pathways for the degradation of limonene and biphenyl. Previously, we found that a gene(s) involved in limonene degradation was also related to indigo-producing ability. To further corroborate this observation, we have cloned and sequenced a 8,842-bp genomic DNA region with four open reading frames, including one for indole oxygenase, which converts indole to indigo (a blue pigment). The reverse transcription PCR data demonstrated that the identified indole oxygenase gene is specifically induced by limonene, thereby implicating this gene in the degradation of limonene by T104.

• Korean Journal of Environmental Agriculture
• /
• v.16 no.4
• /
• pp.341-346
• /
• 1997

The degradation of fungicide oxadixyl in soil amended with manure, chemical fertilizers, heavy metals and detergent was studied. The degradation of oxadixyl in the soil was slow, but became to be fast after the lag phase of about 14 days. The half-life was 10.5 days. The degradation rate was accelerated largely by the amendment of manure. Potassium also promoted the degradation rate but nitrogen and phosphate did not. The heavy metals inhibited the degradation rate, in order of Ni, Cd, Cr, Cu, and Zn. The degradation rate was declined greatly with the addition of synthetic detergent. The microbial biomass and the respiration rate in the soil were increased by the amendment of manure and chemical fertilizers, but decreased by the addition of heavy metals and cleaner. The degradation rate of oxadixyl was positively correlated with the microbial biomass and the respiration rate.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.8
• /
• pp.489-493
• /
• 2017

Microbial fuel cells (MFC) are bio-electrochemical processes that can convert various organic materials present in wastewater into electrical energy. For scaling-up and practical application of MFC, it is necessary to investigate the effect of anode size, electrode distance, and total area of anode on substrate degradation. Spaced electrode assembly (SPA) type microbial fuel cell with multiple anodes treating domestic wastewater was used for simulation. According to computer simulation results, the shorter the distance between electrodes than the size of single electrode, the faster the substrate degradation rate. Particularly, when the total area of the anode is large, the substrate decomposition is the fastest. In this study, it was found that the size of the anode and the distance between the electrodes as well as the cathode electrode, which is known as the rate-limiting step in the design of the microbial fuel cell process, are also important factors influencing the substrate degradation rate.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.13 no.1
• /
• pp.124-130
• /
• 2005

Landfilling is most widely used as the final disposal tool of solid wastes. Solid wastes landfilled are stabilized by microbial degradation which is affected by several factors such as moisture, oxygen, pH, alkalinity, sulphate, nutrient, inhibitor, hydrogen, and temperature. Especially moisture plays a major role in microbial degradation. In this study, the effects of moisture on the degradation of municipal solids waste (MSW) were investigated. Four lysimeters with four different levels of moisture content i.e., 20, 30, 40, and 50% were operated; lysimeters were packed with MSW, and anaerobically operated. Anaerobic lysimeters with higher moisture content produced more $CO_2$ and landfill gases (LFG). It means that the moisture has a positive effect on the microbial degradation.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.5
• /
• pp.585-591
• /
• 2014

To evaluate the potential utility of pretreatment of raw biomass with a complex microbial system, we investigated the degradation of rice straw by BMC-9, a lignocellulose decomposition strain obtained from a biogas slurry compost environment. The degradation characteristics and corresponding changes in the bacterial community were assessed. The results showed that rapid degradation occurred from day 0 to day 9, with a peak total biomass bacterium concentration of $3.3{\times}10^8$ copies/ml on day 1. The pH of the fermentation broth declined initially and then increased, and the mass of rice straw decreased steadily. The highest concentrations of volatile fatty acid contents (0.291 mg/l lactic acid, 0.31 mg/l formic acid, 1.93 mg/l acetic acid, and 0.73 mg/l propionic acid) as well as the highest xylanse activity (1.79 U/ml) and carboxymethyl cellulase activity (0.37 U/ml) occurred on day 9. The greatest diversity among the microbial community also occurred on day 9, with the presence of bacteria belonging to Clostridium sp., Bacillus sp., and Geobacillus sp. Together, our results indicate that BMC-9 has a strong ability to rapidly degrade the lignocelluloses of rice straw under relatively inexpensive conditions, and the optimum fermentation time is 9 days.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.6
• /
• pp.839-847
• /
• 2020

In the present study, an anaerobic microbial consortium for the degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was selectively enriched with the co-addition of RDX and starch under nitrogen-deficient conditions. Microbial growth and anaerobic RDX biodegradation were effectively enhanced by the co-addition of RDX and starch, which resulted in increased RDX biotransformation to nitroso derivatives at a greater specific degradation rate than those for previously reported anaerobic RDX-degrading bacteria (isolates). The accumulation of the most toxic RDX degradation intermediate (MNX [hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine]) was significantly reduced by starch addition, suggesting improved RDX detoxification by the co-addition of RDX and starch. The subsequent MiSeq sequencing that targeted the bacterial 16S rRNA gene revealed that the Sporolactobacillus, Clostridium, and Paenibacillus populations were involved in the enhanced anaerobic RDX degradation. These results suggest that these three bacterial populations are important for anaerobic RDX degradation and detoxification. The findings from this work imply that the Sporolactobacillus, Clostridium, and Paenibacillus dominant microbial consortium may be valuable for the development of bioremediation resources for RDX-contaminated environments.

• KSBB Journal
• /
• v.13 no.2
• /
• pp.220-222
• /
• 1998

Three microbial consortia were screened for their ability to degrade phenolic resin, resole as a sole carbon source. These microbial consortia were derived from soil samples collected from a phenolic resin manufacturing plant site. Among the consortia, the test consortium, designated as MS2, displayed approximately 70% degradation of the substrate, 100 mg of resole per liter, within the fist twelve days of incubation but the degradation was inhibited. During the incubation period, pH was decreased from 7.0 to 2.7, and the resole degradation became inhibited under the conditions. UV-scans of spent culture showed that the wavelength of maximum absorption was 261 nm for resole.

• Biomedical Science Letters
• /
• v.24 no.4
• /
• pp.292-304
• /
• 2018

Microbes is becoming increasingly forensic possibility as a consequence of advances in massive parallel sequencing (MPS) and bioinformatics. Human DNA typing is the best identifier, but it is not always possible to extract a full DNA profile namely its degradation and low copy number, and it may have limitations for identical twins. To overcome these unsatisfactory limitations, forensic potential for bacteria found in evidence could be used to differentiate individuals. Prokaryotic cells have a cell wall that better protects the bacterial nucleoid compared to the cell membrane of eukaryotic cells. Humans have an extremely diverse microbiome that may prove useful in determining human identity and may even be possible to link the microbes to the person responsible for them. Microbial composition within the human microbiome varies across individuals. Therefore, MPS of human microbiome could be used to identify biological samples from the different individuals, specifically for twins and other cases where standard DNA typing doses not provide satisfactory results due to degradation of human DNA. Microbial forensics is a new discipline combining forensic science and microbiology, which can not to replace current STR analysis methods used for human identification but to be complementary. Among the fields of microbial forensics, this paper will briefly describe information on the current status of microbiome research such as metagenomic code, salivary microbiome, pubic hair microbiome, microbes as indicators of body fluids, soils microbes as forensic indicator, and review microbial forensics as the feasibility of microbiome-based human identification.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.14 no.1
• /
• pp.139-150
• /
• 2006

Landfilling is one of the most widely used methods for the final disposal of solid wastes. Landfilled wastes are degraded by residing microorganisms and the microbial degradation is affected by many factors such as moisture, oxygen, pH, alkalinity, sulphate, nutrient, temperature, and so on. Especially among these factor, oxygen and moisture within aerobic landfill play a major role in microbial degradation. In this study, 1) the effects of oxygen on the velocity of waste degradation and 2) the effect of moisture on the degradation of municipal solids waste (MSW) in aerobic condition were investigated. It was found that the BOD and CODcr concentration from the leachate of aerobic lysimeters dropped faster by 80 days after the start of the test compared to those from the anaerobic lysimeters. To see the effect of moisture, four aerobic lysimeters filled with MSW and four different levels of moisture (20, 30, 40, and 50%) were installed. From this test, higher moisture in MSW produced higher $CO_2$ concentration, meaning moisture was effective for the microbial degradation. thus, we concluded that higher moisture level in the aerobic landfill might help early-stabilization microbial degradation.