• 한국식품저장유통학회지
• /
• 제15권5호
• /
• pp.731-735
• /
• 2008

본 연구는 벌꿀의 내포되어 있을 수 있는 미생물의 포자의 제균에 관한 연구로 선행연구로 일반세균, 대장균군, 살모넬라균, 포도상구균을 분석하였으며, 벌꿀 음료 제조 후 유통 중에 문제시 되어지고 있는 내열호산성균의 제균에 관한 연구결과이다. 분석을 위한 내열호산성균 실험법은 진공감압기를 이용하여 $0.45\;{\mu}m$ micro filter를 이용한 막분리 배양법을 이용하였다. 미생물 실험 결과 일반세균, 대장균군, 살모넬라균, 포도상구균은 모두 음성으로 나타났으며, 내열호산성균 제균을 위하여 식품의 일반 살균법을 적용한 결과 농도별 전해수 살균, 오존수 살균, 자외선살균, 일반 마이크로 필터 처리, 고온 가열 살균, microwave 살균 등 모든 제균 방법에서 균이 제어 되지 않는 것으로나타났다. 또한 마이크로 필터를 이용한 제균 처리에서도 일반 (nominal type) 필터를 사용하였을 경우 $44.8{\sim}64.5%$ 제균 효과를 나타낸 반면 absolute type의 필터를 사용하였을 경우 0.45, $0.8\;{\mu}m$ 마이크로 필터의 사용 시 모든 처리구에서 음성으로 나타나 제균 효과가 다른 살균법에 비해우수한 것으로 나타났다.

• 생명과학회지
• /
• 제17권5호
• /
• pp.735-739
• /
• 2007

고온 내산성 미생물을 퇴비에서 분리하고, 생리 및 생화학적 특성을 조사하여 Bacillus sp. SJ-15로 명명하였다. 생장을 위한 최적 온도와 pH는 각각 $55^{\circ}C$와 5.0 이었다. 분리된 SJ-15 균주는 음식물쓰레기의 고온 고속 퇴비화 공정에 적용하였다. 퇴비화 과정에서 16시간 만에 최대 생균수인 $9.2{\times}10^9/ml$를 나타내었다. 본 퇴비화 공정은 개시 100일 후에 약 88%의 감량율을 나타내었고, 퇴비성분의 농도를 분석한 결과 본 공정을 통해 생산된 퇴비는 염분을 제외하면 유기질 비료의 기준을 모두 만족하는 것으로 나타났다.

• 한국미생물학회:학술대회논문집
• /
• 한국미생물학회 2001년도 추계학술대회
• /
• pp.39-45
• /
• 2001

Extremophiles are unique microorganisms that are adapted to survive in ecological niches such as high or low temperatures, extremes of pH, high salt concentrations and high pressure. These unusual microorganisms have unique biochemical features which can be exploited for use in the biotechnological industries. Due to the high biodiversity of extremophilic archaea and bacteria and their existence in various biotopes a variety of biocatalysts with different physicochemical properties have been discovered. The extreme molecular stability of their enzymes, membranes and the synthesis of unique organic compounds and polymers make extremophiles interesting candidates for basic and applied research. Some of the enzymes from extremophiles, especially hyperthermophilic marine microorganisms (growth above $85^{\circ}C$), have already been purified in our laboratory. These include the enzyme systems from Pyrococcus, Pyrodictium, Thermococcus and Thermotoga sp. that are involved in polysacharide modification and protein bioconversion. Only recently, the genome of the thermoalkaliphilic strain. Anaerobranca gottschalkii has been completely sequenced providing a unique resource of novel biocatalysts that are active at high temperature and pH. The gene encoding the branching enzyme from this organism was cloned and expressed in a mesophilic host and finally characterized. A novel glucoamylase was purified from an aerobic archaeon which shows optimal activity at $90^{\circ}C$ and pH 2.0. This thermoacidophilic archaeon Picrophilus oshimae grows optimally at pH 0.7 and $60^{\circ}C$. Furthermore, we were able to detect thermoactive proteases from two anaerobic isolates which are able to hydrolyze feather keratin completely at $80^{\circ}C$ forming amino acids and peptides. In addition, new marine psychrophilic isolates will be presented that are able to secrete enzymes such as lipases, proteases and amylases possessing high activity below the freezing point of water.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVI)
• /
• pp.327-333
• /
• 2005

Dihydroxy-acid dehydratase (DHAD, 2,3-dihydroxy-acid hydrolyase, EC 4.2.1.9) is one of the key enzymes involved in the biosynthetic pathway of the branched chain amino acid isoleucine and valine. Although the enzyme have been purified and characterized in various mesophiles including bacteria and eukarya, the biochemical properties of DHAD has bee not yet reported from hyperthermophilic archaea. In this study, we cloned, expressed, and purified a DHAD homologue from the thermoacidophilic archaeon Sulfolobus solfataricus P2, which grows optimally at $80\;^{\circ}C$ and pH 3, in E. coli. Characterization of the recombinant S. solfataricus DHAD (rSso_DHAD) revealed that it is the dimeric protein with a subunit molecular weight of 64,000 Da in native structure. rDHAD showed the highest activity toward 2,3-dihydroxyisovaleric acid among 17 aldonic acid substrates Interestingly, this enzyme also displayed 50 % activities toward some pentonic acids and hexonic acids when compared with the activity of this enzyme to the natural substrate. Moreover, rSso_DHAD indicated relatively higher activity toward D-gluconate than any other hexonic acids tested in substrates. $K_m$ and $V_{max}$ values of rSso_DHAD were calculated as $0.54\;{\pm}\;0.04\;mM$ toward 2,3dihydroxyisovalerate and $2.42\;{\pm}\;0.19\;mM$ toward D-gluconate, and as $21.6\;{\pm}\;0.4\;U/mg$ toward 2,3-dihydroxyisovalerate and $13.8\;{\pm}\;0.4\;U/mg$ toward D-gluconate, respectively. In the study for biochemical properties, the enzyme shows maximal activity between $70^{\circ}C$ and $80^{\circ}C$, and the pH range of pH 7.5 to 8.5. The half life time at $80^{\circ}C$ was 30 min. A divalent metal ion, $Mn^{2+}$, was only powerful activators, whereas other metal ions made the enzyme activity reduced. $Hg^{2+}$, organic mercury, and EDTA also strongly inhibited enzyme activities. Particularly, the rSso_DHAD activity was very stable under aerobic condition although the counterparts reported from mesophiles had been deactivated by oxygen.