• Korean Journal of Environmental Biology
• /
• v.25 no.3
• /
• pp.267-272
• /
• 2007

Microorganisms capable of degrading poly(butylene succinate-co-butylene adipate) (PBSA) were isolated from 40 soil samples such as landfill site soil, cultivating soil and activated sludge soil from 20 different sites in Korea by using the enrichment culture and the clear zone test at $37^{\circ}C$. Based on the 16S rDNA sequences, the isolated bacterium was identified to be Streptomyces sp. PBSA-1. Morphological and cultural characteristics were employed for the identification of the isolated fungi and they were proved to be Aspergillus fumigatus PBSA-2 and Aspergillus fumigatus PBSA-3. The PBSA degradation activity of the isolated microorganisms was enhanced through the serial acclimation in PBSA plate medium. The PBSA degrading microorganisms appeared to be highly active for the PBSA degradation in that 83% of PBSA was degraded by Streptomyces sp. PBSA-l, and 65% and 75% of PBSA was mineralized by A. fumigatus PBSA2 and A. fumigatus PBSA-3 respectively during 40 days of the modified Sturm test.

• Korean Journal of Environmental Biology
• /
• v.27 no.2
• /
• pp.198-204
• /
• 2009

From leaf mold and reclamation site soil of the Capital area of Korea, 3 poly(butylene succinate-co-butylene adipate: PBSA)-degrading strains were isolated through the clear zone test. The PBSA-degrading activities of the strains were assessed by means of a modified Sturm test using 0.01% of PBSA film as a sole carbon source. After the modified Sturm tests for 40 days at the respective isolation temperatures, the 3 strains degraded 30%, 55% and 43% of PBSA, respectively. The isolated strains were identified to be Burkholderia cepacia PBSA-4, Bacillus licheniformisPBSA-5 and Burkholderia sp. PBSA-6 through the 16S rDNA gene sequence analysis. Among them, PBSA-5 degraded both PBSA and Poly(vinyl alcohol). The degradation activity of the PBSA degrading strains appeared to be high at moderate temperatures such as $27^{\circ}C$ and $37^{\circ}C$, and initial inoculum size of $10^{10}cfu\;mL^{-1}$ degraded PBSA 1.2~1.3 more times than that $10^9cfu\;mL^{-1}$. Addition of 0.1 or 0.5% (w/w) of gelatin, yeast extract and ammonium sulfate raised the PBSA degrading activity, and especially addition of 0.1% (w/w) of gelatin enhanced the PBSA degrading activity by more than 33%. The mixed strains degraded PBSA faster than the single strain.

• Korean Journal of Environmental Biology
• /
• v.28 no.2
• /
• pp.95-100
• /
• 2010

Burkholderia cepacia PBSA-7, Bacillus licheniformis PBSA-8 and Burkholderia sp. PBSA-9 previously collected from Korea soil (Joo and Kim, 2009) were analyzed for the presence of genes encoding proteins operative in the degradation of poly(butylene succinate-co-butylene adipate; PBSA). Polymerase chain reaction analyses revealed a 1.5 kb fragment of the lipase gene (lip A) in B. cepacia PBSA-7 and Burkholderia sp. PBSA-9, while B. licheniformis PBSA-8 harbored the same gene fragment at 600 bp. The three strains possessed "Gly-X1-Ser-X2-Gly" and "Ala-X1-Ser-X2-Gly" lipase sequence regions. Burkholderia sp. PBSA-7 lip A displayed 36~40% homology with the family 1-1 lipases and 82~92% homology with the family 1-5. Burkholderia sp. PBSA-8 lip A was 64~65% homologous with the subfamily 1-4 lipases, but displayed no homology with the subfamily 1-5 lipases. Burkholderia sp. PBSA-9 lip A displayed 35~37% homology with the family I1 lipases and 83~94% homology with the family I2 lipases, similar to Burkholderia sp. PBSA-7.

• Korean Journal of Environmental Biology
• /
• v.28 no.3
• /
• pp.150-157
• /
• 2010

Biodegradation behavior of poly(butylene succinate-co-butylene adipate) (PBSA) was examined when PBSA was buried in the natural soil and the soil inoculated with Burkholderia cepacia after sterilization. After 80 days of the soil burial test at room temperature, the PBSA film buried in the natural soil lost 34.0% of its intial weight, while the same film lost 59.2% of its initial weight when buried in the sterile soil inoculated with B. cepacia. The optical and SEM observations of the surface morphology of the PBSA film also indicated that the surface erosion and rupture took place faster when the film was buried in the sterile soil inoculated with B. cepacia compared to the film buried in the natural soil. Viable cell number in the natural soil and that the sterile soil inoculated with B. cepacia increased by a factor of 6~7 and 10~14, respectively as compared to the initial viable cell number.

• Korea-Australia Rheology Journal
• /
• v.17 no.2
• /
• pp.71-77
• /
• 2005

We investigated thermal, rheological, morphological and mechanical properties of a binary blend of poly(lactic acid) (PLA) and poly(butylene succinate adipate) (PBSA). The blends were extruded and their molded properties were examined. DSC thermograms of blends indicated that the thermal properties of PLA did not change noticeably with the amount of PBSA, but thermogravimetric analysis showed that thermal stability of the blends was lower than that of pure PLA and PBSA. Immiscibility was checked with thermal data. The rheological properties of the blends changed remarkably with composition. The tensile strength and modulus of blends decreased with PBSA content. Interestingly, however, the impact strength of PLA/PBSA (80/20) blend was seriously increased higher than the rule of mixture. Morphology of the blends showed a typical sea and island structure of immiscible blend. The effect of the blend composition on the biodegradation was also investigated. In the early stage of the degradation test, the highest rate was observed for the blend containing $80wt\%$ PBSA.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.54 no.2
• /
• pp.135-142
• /
• 2009

This experiment was conducted to determine the usability of biodegradable plastic in the mulching cultivation of sweetpotato. For this, we investigated the physical characteristics, biodegradability, leaching, yield, workability, etc. of biodegradable films. Compared with general mulching materials, biodegradable Poly butyleneadipate-co-butylene succinate (PBSA) and PLC+starch showed $2{\sim}27$% higher tensile strength, but $2{\sim}22$% lower elongation and $2{\sim}6$% lower tear strength. In the leaching test on the biodegradable films, heavy metals were detected very little or not at all. As to difference in ground temperature according to mulching material, the temperature was high in order of PLC+starch > PBSA > Low Density Polyethylene (LDPE) > Control during the period from late June to mid July, but in order of LDPE > PLC+starch > PBSA > None during the period from late July to late September. In the mulching cultivation of sweet potato, biodegradable films PBSA (EA, EB, EC) and PLC+starch (DD, DE, DF) began to degrade after 60 days from the cut planting of sweet potato, and over 95% degraded after 120 days. The quantity of roots was 3,070 kg/10a for PBSA, 3,093 kg/10a for PLC-starch, and 2,946 kg/l10a for LDPE, showing no significant difference according to mulching material. Considering the physical characteristics, biodegradability, environment, convenience in harvesting work, yield, etc. of the films in the mulching cultivation of sweet potato, biodegradable films are expected to be very useful.

• The monthly packaging world
• /
• s.150
• /
• pp.140-143
• /
• 2005

식품의약품안전청은 기구 및 용기 포장의 재질로 사용되는 폴리부틸렌숙시네이트(PBSA) 재질을 신설하는 내용을 입안.예고 했다. PBSA 수지는 토양매립시 자연에서 분리되는 친환경 소재로 최근 일회용 식품용기 등에 사용이 가능하다. 본고에서는 개정(안)과 신.구조문을 비교해 살펴본다.

• Korean Journal of Environmental Biology
• /
• v.26 no.3
• /
• pp.247-251
• /
• 2008

Degradation behavior in the seawater of Tongyeong, Incheon, Kunsan and Hongsung was explored for Mater-Bi$^{(R)}$, poly(3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV), poly(butylene succinate-co-butylene adipate) (PBSA) and polycaprolactone (PCL) which can eventually be used for various fishery tools. Acinetobacter lwoffu/junii and Shewanella algae/putrefaciens inhabited all the seawater samples. Eikenella corrodens was also detected in all the seawater samples, although identified with poor confidence by VITEK system. Mater-Bi$^{(R)}$ was degraded faster than PHBV, PBSA and PCL in the seawater in contradiction to the degradation behavior in soil environment. The seawater retrieved from Incheon exhibited the most elevated activity for the plastic degradation, which may be partly ascribed to the largest number of total viable counts.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3719-3726
• /
• 2012

Formation of Z-DNA, a left-handed double helix, from B-DNA, the canonical right-handed double helix, occurs during important biological processes such as gene expression and DNA transcription. Such B-Z transitions can also be induced by high salt concentration in vitro, but the changes in the relative stability of B-DNA and Z-DNA with salt concentration have not been fully explained despite numerous attempts. For example, electrostatic effects alone could not account for salt-induced B-Z transitions in previous studies. In this paper, we propose that the B-Z transition can be explained if counterion entropy is considered along with the electrostatic interactions. This can be achieved by conducting all-atom, explicit-solvent MD simulations followed by MM-PBSA and molecular DFT calculations. Our MD simulations show that counterions tend to bind at specific sites in B-DNA and Z-DNA, and that more ions cluster near Z-DNA than near B-DNA. Moreover, the difference in counterion ordering near B-DNA and Z-DNA is larger at a low salt concentration than at a high concentration. The results imply that the exclusion of counterions by Z-DNA-binding proteins may facilitate Z-DNA formation under physiological conditions.

• Journal of Integrative Natural Science
• /
• v.5 no.4
• /
• pp.216-219
• /
• 2012

Structure-based drug design possibly benefit from in silico methods that precisely predict the binding affinity of small molecules to target macromolecules. There are many limitations arise from the difficulty of predicting the binding affinity of a small molecule to a biological target with the current scoring functions. There is thus a strong interest in novel methodologies based on MD simulations that claim predictions of greater accuracy than current scoring functions, helpful for a regular use designed for drug discovery in the pharmaceutical industry. Herein, we report a short review on free energy calculations using MMPBSA method a useful method in structure based drug discovery.