• Journal of Microbiology and Biotechnology
• /
• 제22권3호
• /
• pp.283-291
• /
• 2012

Bioremediation efforts often rely on the application of surfactants to enhance hydrocarbon bioavailability. However, synthetic surfactants can sometimes be toxic to degrading microorganisms, thus reducing the clearance rate of the pollutant. Therefore, surfactant-resistant bacteria can be an important tool for bioremediation efforts of hydrophobic pollutants, circumventing the toxicity of synthetic surfactants that often delay microbial bioremediation of these contaminants. In this study, we screened a natural surfactant-rich compartment, the estuarine surface microlayer (SML), for cultivable surfactant-resistant bacteria using selective cultures of sodium dodecyl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB). Resistance to surfactants was evaluated by colony counts in solid media amended with critical micelle concentrations (CMC) of either surfactants, in comparison with non-amended controls. Selective cultures for surfactant-resistant bacteria were prepared in mineral medium also containing CMC concentrations of either CTAB or SDS. The surfactantresistant isolates obtained were tested by PCR for the Pseudomonas genus marker gacA gene and for the naphthalene-dioxygenase-encoding gene ndo. Isolates were also screened for biosurfactant production by the atomized oil assay. A high proportion of culturable bacterioneuston was tolerant to CMC concentrations of SDS or CTAB. The gacA-targeted PCR revealed that 64% of the isolates were Pseudomonads. Biosurfactant production in solid medium was detected in 9.4% of tested isolates, all affiliated with genus Pseudomonas. This study shows that the SML is a potential source of surfactant-resistant and biosurfactant-producing bacteria in which Pseudomonads emerge as a relevant group.

• Journal of Advanced Marine Engineering and Technology
• /
• 제26권2호
• /
• pp.240-247
• /
• 2002

Recently, a thermal energy storage system has been developed actively fur the purpose of saving energy and reducing the peak electrical demand. Especially, ice slurry is a promising working fluid for low temperature energy storage systems. A flow of ice crystals has a large cooling capacity as a result of the involvement of latent heat. However, there are still problems related to the recrystallization of ice crystals for realizing long term storage and long distance transportation. To find improvements fur this, a method for the creation of ice crystals resistant to recrystallization has been proposed and researched by the use of an antifreeze protein (AFP) solution etc. In the present study, it has been investigated the growth of ice crystal in several kinds of water solution added non-ionic surfactant. The results shows that size of ice crystal was smaller with increasing in added surfactant. And ice crystal was not increased with added surfactant.

• Journal of Microbiology and Biotechnology
• /
• 제29권5호
• /
• pp.765-775
• /
• 2019

A new ${\alpha}$-amylase-encoding gene (amySL3) of glycoside hydrolase (GH) family 13 was identified in soda lake isolate Alkalibacterium sp. SL3. The deduced AmySL3 shares high identities (82-98%) with putative ${\alpha}$-amylases from the genus Alkalibacterium, but has low identities (<53%) with functionally characterized counterparts. amySL3 was successfully expressed in Escherichia coli, and the recombinant enzyme (rAmySL3) was purified to electrophoretic homogeneity. The optimal temperature and pH of the activity of the purified rAmySL3 were determined to be $45^{\circ}C$ and pH 7.5, respectively. rAmySL3 was found to be extremely halophilic, showing maximal enzyme activity at a nearly saturated concentration of NaCl. Its thermostability was greatly enhanced in the presence of 4 M NaCl, and it was highly stable in 5 M NaCl. Moreover, the enzyme did not require calcium ions for activity, and was strongly resistant to a range of surfactants and hydrophobic organic solvents. The major hydrolysis products of rAmySL3 from soluble starch were maltobiose and maltotriose. The high ratio of acidic amino acids and highly negative electrostatic potential surface might account for the halophilic nature of AmySL3. The extremely halophilic, calcium-independent, and surfactant-resistant properties make AmySL3 a promising candidate enzyme for both basic research and industrial applications.

• 대한화장품학회지
• /
• 제45권2호
• /
• pp.199-208
• /
• 2019

본 연구는 poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG) 삼중블록 고분자 계면활성제를 이용하여 제조된 우수한 사용감과 선택적인 클렌징 효과를 갖는 수중유(O/W) 에멀젼 타입의 내수성 자외선 차단 제형에 관한 것이다. 수영, 등산 등 다양한 야외 레저 활동이 많아짐에 따라 내수성 자외선 차단제의 수요가 증가하고 있다. 내수성 자외선 차단제는 물이나 땀에 지워지지 않아야하기 때문에 대부분 유중수(W/O) 에멀젼 제형으로 만들어진다. 하지만, W/O 에멀젼 제형은 오일리한 사용감과 클렌징이 어렵다는 단점이 있다. 이에 비해 O/W 에멀젼 제형은 사용감이 우수하고, 클렌징도 용이하지만, 물과의 재유화가 쉽기 때문에 내수성 특성을 갖는 것이 매우 어렵다. 본 연구에서는 이러한 문제를 해결하기 위해 O/W 에멀젼 제형의 HLB 값(~ 10)을 가지면서도 상대적으로 높은 계면장력을 가짐으로써 재유화에 강한 삼중블록 고분자 계면활성제를 도입하였고, 이를 통해 O/W 에멀젼형 지속내수성 자외선 차단제를 개발하였다. 본 연구를 통해 개발된 자외선 차단제는 우수한 사용감과 지속내수성, 그리고 폼 클렌저와의 선택적인 클렌징 효과를 보여준다. 향후 사용감이 다양화된 새로운 O/W 에멀젼형 자외선 차단제 제품 개발에 도움이 될 것으로 기대된다.

• Environmental Engineering Research
• /
• 제10권3호
• /
• pp.138-143
• /
• 2005

Laboratory batch experiments were conducted to evaluate the Fenton degradation rates of phenanthrene. Fenton reactions for the degradation of phenanthrene were carried out with aqueous and slurry phase, to investigate the effects of sorption of phenanthrene onto solid phase. Various types of surfactants and electrolyte solutions were used to evaluate the effects on the phenanthrene degradation rates by Fenton's reaction. A maximum 90% removal of phenanthrene was achieved in aqueous phase with 0.9% of $H_2O_2$ and 300 mg/L of $Fe^{2+}$ at pH 3. In aqueous phase reaction, inhibitory effects of synthetic surfactants on the removal of phenanthrene were observed, implying that surfactant molecules acted as strong scavenger of hydroxyl radicals. However, use of $carboxymethyl-{\beta}-cyclodextrin$ (CMCD), natural surfactant, showed a slight enhancement in the degradation of phenanthrene. It was considered that reactive radicals formed at ternary complex were located in close proximity to phenanthrene partitioned into CMCD cavities. It was also show that Fenton degradation of phenanthrene were greatly enhanced by addition of NaCl, indicating that potent radical ion ($OCI^-$) played an important role in the phenanthrene degradation, although chloride ion might be acted as scavenger of radicals at low concentrations. Phenanthrene in slurry phase was resistant to Fenton degradation. It might be due to the fact that free radicals were mostly reacting with dissolved species rather than with sorbed phenanthrene. Even though synthetic surfactants were added to increase the phenanthrene concentration in dissolved phase, low degradation efficiency was obtained because of the scavenging of radicals by surfactants molecules. However, use of CMCD in slurry phase, showed a slight enhancement in the phenanthrene degradation. As an alternative, use of Fenton reaction with CMCD could be considered to increase the degradation rates of phenanthrene desorbed from solid phase.

• Journal of the Korean Wood Science and Technology
• /
• 제52권2호
• /
• pp.145-156
• /
• 2024

Unlike resistant cells, persister cells resist antibiotics due to a decreased cellular metabolic rate and can transition back to normal susceptible cells when the antibiotic is removed. These persister cells contribute to the chronic symptoms of infectious diseases and promote the emergence of resistant strains with continuous antibiotic exposure. Therefore, eliminating persister cells represents a promising approach to significantly enhance antibiotic efficacy. Here, we found that Coicis Semen extract reduced Staphylococcus aureus persister cells at a concentration of 0.5 g/L. Linoleic acid and oleic acid, the major components of Coicis Semen extract, exhibited a comparable reduction in persister cells when combined with three antibiotics: ciprofloxacin, oxacillin, and tobramycin. Conversely, these effects were nullified in the presence of the surfactant Tween 80 (1%), suggesting that the hydrophobic characteristics of linoleic acid and oleic acids play a pivotal role in reducing the number of S. aureus persister cells. Considering the concentration-dependent effects of linoleic acid and oleic acid, the persister-reducing activity of Coicis Semen extract was primarily attributed to these fatty acids. Moreover, Coicis Semen extract, linoleic acid, and oleic acid increased the cell membrane permeability of S. aureus. Interestingly, this effect was counteracted by 1% Tween 80, indicating a close association between the reduction of persister cells and the increase in cell membrane permeability. The identified compounds could thus be used to eliminate persister cells, thereby enhancing therapeutic efficacy and shortening treatment duration. When used in conjunction with antibiotics, they may also mitigate chronic symptoms and significantly reduce the emergence of antibiotic-resistant bacteria.

• 한국의류학회지
• /
• 제2권1호
• /
• pp.167-176
• /
• 1978

The effect of additives in final rinse water during laundering on soiling, soil removal and some properties of fabrics has been studied with various fabrics. The additives examined were fabric softener (Sta-Puf), cationic surfactant (Apole PS), sizing materials such as CMC, PYA, cornstarch and mixture of CMC and cationic surfactant. The results obtained may be summerized as follows. L Addition of additives except PVA in final rinse water generally reduce the deposition of carbon-$CCl_4$ soil and it seems to be rather independant of the concentration of additives. The effect of additives on soil resistant is found to increase in the following order. cotton; Apole

• KSBB Journal
• /
• 제17권2호
• /
• pp.176-181
• /
• 2002

Astaxanthin (3,3＇-dihydroxy-${\beta}$, ${\beta}$-carotene-4-4＇-dione), a natural pigment of pink to red color, is widely distributed in nature particularly in the skin layer of salmonoids and the crust of shrimp, lobster, etc. Recently, it was produced from the yeast culture of Phaffia rhodozyma. Because of its high thermal stability and antioxidant functionality, its applications can be extended into food, cosmetics, and pharmaceutical ingredient beyond the traditional feed additive. Because of its very high lipophilicity, astaxanthin has been extracted traditionally by strong organic solvents such as chloroform, petroleum ether, acetone, etc. In this study, we developed a surfactant-based solubillization system for astaxanthin, and used it to extract astaxanthin from disrupted yeast cells. Among Tween 20, Triton X-100 and SDS, Tween 20 was identified as the most suitable surfactant in terms of extraction capacity and safety. The ethylene oxide group of Tween 20 was identified as the most significant factor to increase the HLB value that determined the extraction capacity. The effects of micelle formation condition, such as the molar ratio of astaxanthin and Tween 20, pH, and ionic strength were also investigated. pH and ionic strength showed no significant effects. The optimal molar ratio between astaxanthin and Tween 20 was 1 : 12. Antioxidant activity of astaxanthin was higher than ${\beta}$-carotene and ${\alpha}$-tocopherol. Astaxanthin in the crude extract from the yeast cell was more resistant to air and/or light degradation than pure astaxanthin, probably because of the presence of other carotenoids and lipids.

• 한국구조물진단유지관리공학회 논문집
• /
• 제20권2호
• /
• pp.60-66
• /
• 2016

본 연구는 실리콘계 정포제의 특성에 따른 폴리우레탄 폼 지수제의 cell 구조와 흡수량 변화를 알아보기 위하여 6종의 정포제를 사용하여 폴리우레탄 폼 지수제를 제조하여 FE-SEM으로 분석한 결과 실리콘 정포제의 실록산 주사슬 말단에 PO n개가 결합되어 있는 DC-193, DC-2585, DC-5125, DC-198의 cell 구조는 close cell로 확인이 되었고, 실리콘 정포제의 실록산 주사슬 말단에 EO n개가 결합 되어 있는 DC-5043과 DC-5598은 open cell 구조로 나타났다. 또한 cell 구조 변화에 따른 흡수량 에서는 close cell의 크기가 가장 세밀하고 균일한 DC-193의 흡수량이 가장 적게 나타나 내수성이 가장 우수한 것으로 나타났으며 open cell의 크기가 가장 크게 형성된 DC-5043의 흡수량이 가장 많은 것으로 나타났다. 이들의 방수성능을 콘크리트 구조물을 모사하여 시험한 결과 누수가 없음을 확인하였다.

• Journal of Pharmaceutical Investigation
• /
• 제35권2호
• /
• pp.95-99
• /
• 2005

Mucoadhesive microspheres were prepared by interpolymer complexation of chitosan with poly(acrylic acid) (PAA) and solvent evaporation method to increase gastric residence time. The chitosan-PAA complex formation was confirmed by differential scanning calorimetry and swelling study. The DSC thermogram of chitosan-PAA microspheres showed two exothermic peaks for the decomposition of chitosan and PAA. The swelling ratio of the chitosan-PAA microspheres was dependent on the pH of the medium. The swelling ratio was higher at pH 2.0 than at neutral pH. The results indicated that the microspheres were formed by electrostatic interaction between the carboxyl groups of PAA and the amine groups of chitosan. The effect of various process parameters on the formation and morphology of microspheres was investigated. The best microspheres were obtained when 1.5% of the high molecular weight chitosan and 0.3% of PAA were used as an internal phase. The optimum internal phase volume was 7%. The com oil was used as the external phase of emulsion, and span 80 was used as the surfactant. The prepared microspheres had spherical shape.