In order to investigate novel insect growth regulators (IGRs) from actinomycetes, 363 isolates of actinomycetes were tested for their IGR activities. Among them, Streptomyces sp. AN120537 showed the highest juvenile hormone antagonist (JHAN) activity and significant insecticidal activities against larvae of Aedes albopictus and Plutella xylostella. In addition, the dead larvae showed morphological deformities such as contraction of body segments or pigmentation of all body parts. Through liquid chromatography and bioassay-guided fractionation, 7 IGR compounds were identified from the crude hexane extract of AN120537. These results suggested that Streptomyces sp. AN120537 could be useful resources for development of eco-friendly insecticidal agents.

Streptomyces has been reported to produce various secondary metabolites which have the potential to become environmentally safe insecticides. In this study, 1,274 streptomyces culture filtrates were screened for their JHAN activity in order to identify novel insecticidal compounds. 34 isolates with high levels of JHAN activity were selected, and their insecticidal activities were tested against Plutella xylostella larvae. Among them, IMBL-263 which was revealed to be Streptomyces anulatus by 16s rRNA sequencing showed the highest insecticidal activity. Also, systemic activities of secondary metabolites extracted from the S. anulatus on plant, Brassica napus, were investigated. These results suggested that secondary metabolites from the S. anulatus might be useful for development of novel environmentally benign insecticides.

Beet armyworm, Spodoptera exigua, is known to be hard-to-kill pest by having high resistance to insecticides and its control is intensely dependent on fewer insecticides. In this study, the ethyl acetate extract of Streptomyces sp. was evaluated to find novel insecticidal agents against S. exigua. In order to determine the identity of insecticidal compounds, the crude ethyl acetate extract was fractionated based on the TLC profiling and bioassay-guided monitoring. These results indicated that the non-polar fraction have high level of insecticidal activity against second instars of S. exigua. These findings suggested that secondary metabolites produced by Streptomyces sp. could be considerable potential resources as novel insecticidal formulation candidates.

A xylanolytic microorganism, strain DY-7, was isolated from the gut of the mole cricket, Gryllotalpa orientalis. The result of phylogenetic analysis based on its 16S rDNA sequence revealed that the isolate was a Gram-positive bacterium belonging to the genus Streptomyces. The cloned gene (1350-bp) encoding a GH family 10 β -1,4-xylanase (XylA) from Streptomyces sp. strain DY-7 was overexpressed in Escherichia coli BL21 and its gene products were characterized. The hydrolysis activities of rXylA and rXylAΔCBD II against xylosidic materials were maximum at pH 5.5 and 65oC. However, deletion of CBD II in the C-terminus region of XylA significantly increased the thermal stability of the enzyme at high temperatures above 50oC. The xylanolytic activity of rXylA was slightly enhanced in the presence of 1 mM Mn2+ and 5 mM sodium azide but it was completely inactivated by 1 mM Hg2+ and 5 mM N-bromosuccinimide. rXylA was capable of efficiently decomposing various xylosidic compounds, PNP-cellobioside, and PNP-xylopyranoside, whereas other hexose-based compounds were insensitive to the enzyme. The specific activities of rXylA toward oat spelts xylan and PNP-cellobioside were 649.8 U/mg and 328.1 U/mg, respectively. Enzymatic degradation of birchwood xylan and xylooligosaccharides (xylotriose to xylohexaose) resulted in the production of xylobiose (>75%) as the main hydrolysis product together with a small amount (4%<) of xylose as the final hydrolysis product.

항진균 활성 관련 단백질을 탐색하기 위해 미역류로부터 식물병원성 곰팡이의 생장을 저해하는 SAR01 균주를 분리하였고, FAME (fatty acid methyl ester) 분석 결과, Streptomyces sp.로 동정되었다. 방사선 조사(60Co)를 실시한 결과, Botrytis cinerea를 포함한 5종의 식물병원성 곰팡이에 대한 항진균 활성을 소실한 SAR535 균주 외 6종의 돌연변이 균주가 유도되었다. SAR01 야생형 균주와

Streptomyces sp. NS15 균주로부터 비단백질성 α-glucosidase 저해제의 생산을 위해 초기 배지의 최적 pH와 질소원, 탄소원, 금속 이온, 교반속도 및 통기량 등의 효과에 대하여 조사하였다. 배지의 초기 최적 pH는 7.0이었으며 가장 효과적인 질소원과 탄소원은 각각 soybean meal 2.0%(w/v)와 glucose 1.6%(w/v)였으며 금속이온에서는 Fe^+2에서 저해활성에 있어서 약간의 상승효과를 나타낸 반면 Cu^+2은 오히려 활성저하를 보였다. Jar fermentor 배양에서의 교반속도와 통기량은 각각 400rpm과 1vvm에서 효과적이었으며 최적 배지와 최적조건 하에서 4일간 배양한 배양여액의 저해활성이 돼지 소장의 α-glucosidase에 대해 3, 200units/ml로 기본배지(CYM)에서 보다 25배 높은 저해활동을 보였고 5일째부터는 저해활성이 점차 감소하는 양상을 보였다.

항생제에 대한 내성균의 출현은 매년 급격하게 증가되고 있으며 이에 대한 약제 개발이 요구되고 있다. 특히 메치실린내성 황색 포도상구균(MRSA)은 여러 항생물질에 대하여 다제내성을 나타내므로 감염증 치료에 어려운 문제점으로 남아 있다. 이러한 감염증치료에 사용할 목적으로 임상 가검물에서 분리한 MRAS를 시험균으로 사용하여 항균 활성이 강한 방선균인 YSK-681을 선별하였다. 균주 동정을 위하여 선별된 YSK-681을 형태적, 배양학적, 생리적, 화학적 분석을 하였으며 41개의 단위 항목을 조사하여 TAXON program으로 수리 동정한 결과 주군집 29에서 속하는 Streptomyces lydicus로 동정하였다.

본 실험에서는 GI활성이 높은 alkalophilic Streptomyces sp.를 사용하여 2% k-carrageenan에 균체를 고정화한 후 고정화 균체의 효소학적 특성을 살펴보았다. pH stability는 pH가 7.5∼8.5에서 GI활성이 가장 높았으며, reaction temperature는 70℃, Co^2+는 10 exp (-3)M, Mg^2+는 10 exp (-3)M일 때 GI 활성이 가장 높은 것으로 나타났다.

Experiments were performed using sweet potato starch-wheat composite flours to study the rheology and baking properties of bread with composite flours and to test sensory characteristics. Doughs were prepared from mixtures containing wheat flour and 10, 20, and 30% of sweet potato starch(SPS). Standard methods were used to evaluate the rheology and characteristics of wheat composite flour. The results were as follows : 1. The water absorption, developing time and stability measured by farinograph tended to decrease as SPS contents increased. 2. As the contents of SPS increased, the maximum viscosity of the composite flour by amylograph increased, yet gelatinization temperature was slightly low. 3. In the extensograph, extensibility decreased but the ratio of resistence to extensibility increased in proportion to the contents of SPS. 4. In the quality scoring of the bread, WF, WF + SPS 10%, WF + SPS 20% and WF SPS 30% were 84, 80, 77, 73, respectively. Specific volume and crumb characteristics of bread became inferior as SPS contents increased.