MDPIActa Medica Okayama2076-26071292024A Novel C-Terminal Truncated Bacteriocin Found by Comparison between Leuconostoc mesenteroides 406 and 213M0 Isolated from Mongolian Traditional Fermented Milk, Airag1781ENChihiroHasiqimugeGraduate School of Environmental and Life Science, Okayama UniversityChihiroHanoGraduate School of Environmental and Life Science, Okayama UniversityKensukeArakawaGraduate School of Environmental and Life Science, Okayama UniversitySakiYoshidaGraduate School of Environmental and Life Science, Okayama UniversityJunliangZhaoGraduate School of Environmental and Life Science, Okayama UniversityHidehiroTohAdvanced Genomics Center, National Institute of GeneticsHidetoshiMoritaGraduate School of Environmental and Life Science, Okayama UniversityTakuMiyamotoGraduate School of Environmental and Life Science, Okayama UniversityBacteriocins produced by lactic acid bacteria are known to be useful tools for food biopreservation and fermentation control. Leuconostoc mesenteroides subsp. mesenteroides 406 and 213M0 isolated from different samples of Mongolian traditional fermented milk, airag, had been reported to produce listericidal bacteriocin-like inhibitory substances with similar but slightly different properties. In this study, the antibacterial properties and the related gene sequences of both strains were compared, and then their bacteriocins were purified and identified. Strain 406 was superior to strain 213M0 in cell growth and antibacterial activity against many strains. However, the activity of 213M0 was stronger than that of 406 against a few strains. DNA sequencing revealed two and three plasmids in 406 and 213M0, respectively, and each one of them harbored an almost identical mesentericin Y105-B105 gene cluster. Removal of these plasmids resulted in a complete loss of activity, indicating that the antibacterial activity of both strains was generated by bacteriocins encoded on the plasmids. Mesentericins Y105 and B105 were purified from both cultures, and another novel bacteriocin, named mesentericin M, was identified from the 213M0 culture only. Its structural gene was coded on a 213M0 plasmid and, surprisingly, its C-terminal three amino acid residues were post-translationally cleaved. To our knowledge, this is the first report of a C-terminal truncated bacteriocin. In conclusion, the novel bacteriocin should be mainly responsible for the difference in antibacterial properties between the two strains.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551042015モンゴルの伝統的アルコール発酵乳アイラグに関する微生物学的研究3547ENTakuMiyamoto Airag, a traditional fermented milk well loved by Mongolians, has been drunk habitually since
ancient times as a unique drink. It is produced from cow, mare and camel milk by a traditional method using indigenous starter cultures containing lactic acid bacteria, yeasts and other fermentative microorganisms. Spontaneously fermented milk products have for centuries been consumed for their therapeutic value in promoting health and well-being, especially among the pastoral communities in Mongolia. Most traditional fermentations are conducted as uncontrolled processes, however, increasing
research, such as that focused on compositional properties and microbial biota properties, offers
prospective views for improving spontaneous fermented products with respect to safety, shelf life, sensory characteristics, and nutritional and functional qualities. The aim of this article is to investigate progress in the microbiological research on the traditional alcoholic fermented milk, airag, in Mongolia and to give an outline of the traditional preparation processes.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548511996Lactic Acid and Diacetyl Production of Nitrosoguanidine Mutants Derived from Lactobacillus casei 34143 in Soymilk4550ENTakuMiyamotoNarra SrinivasReddyKeiKataokaProduction of acid and diacetyl by nitrosoguanidine mutants of Lactobacillus casei 34143 was evaluated in soymilk. Optimum temperature for growthof the five cultures varied between 34.5 and 35.9℃. However, the temperature required for maximum production of diacetyl in soymilk in the parent culture was 32.7℃ and mutants such as N-14, N-15 and N-25 required a temperature of 29.6℃, while another mutant, L-7 required 26.4℃ for production of diacetyl. Parent and mutant cultures were deficient in citrate permease and citritase synthetic mechanisms, although lactose-utilising mutants (N-25 and S-3-1) possessed both β-galactosidase and phospho-β-galactosidase.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548711998食品汚染細菌に対して抗菌活性を示す乳酸菌の分離とその抗菌特性163167ENTakuMiyamotoOsamuMorinakaHiroshiMatsumotoKeiKataokaSoo JongMokThe 124 strains of lactic acid bacteria in this study were screened for antibacterial activities against food spoilage bacteria. All lactic strains were fermented for 3-5 days in 10% reconstituted skim milk supplemented with 0.5% yeast extract and 0.5% glucose. Culture filtrates from skim milk media adjusted to pH 4.5, centrifuged at 15,000-rpm and filter-sterilized for antagonistic activities by paper disc assays, using Escherichia coli, Pseudomonas fragi, Staphylococcus aureus and Bacillus subtilis as test organisms. One out of 124 lactic strains showed greater inhibitory activities against the 4 test organisms. The strain from lnner Mongolian cheese, designated as IMC-1, belonged to the Lactobacillus acidophilus group and was selected for further studies. This strain showed considerable inhibitory effects against other lactic strains such as Lactobacillus helveticus and Streptococcus thermophilus under conditions that reduced the effects of organic acids. The antibacterial activities against Pseudomonas fragi IFO 3458 were lost at more than ph 5.2 and remaining inhibition rate after treatments at 121℃ for 20 min was approximately 63.5%. The antibacterial substance was extracted from skim milk culture filtrates with ethanol and was passed through Sephadex G-25 columns. It was presumed to be a bacteriocin-like substance with a moleculr weight of 1,000〜3,500.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548811999カマンベールチーズの熟成中における軟化と塩類の動態7985ENKeiKataokaKazutakaNukadaTamaoKimuraTakefumiYoneyaTakuMiyamotoExperimental Camembert cheese softened from the surface to the center portion after 3-4 weeks of ripening.As ripening progressed,pH value rose from 4.5 to 7.8,lactic acid content decreased from 1.0% to 0.1%,ammonia content increased from 0.04g to 0.063g/100g,calcium content decreased from 0.3g to 0.048g/100g and phosphorus content decreased from 0.25g to 0.12g/100g in the center portion of cheese. The changes in these values were considered as criteria leading to softening of mold surface-ripened cheeses.Mold starter Penicillium candidum AM used the cheese manufacture possesses the abilities lactic acid,producing ammonia and lowering pH when supplemented with lactic acid and peptone Czapek Dox solution.However,normal softening was not observed by incubation of green cheese under ammonia atomsphere conditions.Also,lactic acid free cheese did not soften in spite of mold growth.It is proposed that the primary factor of softening in mold surface-ripened cheese is a rise of casein solubility caused by lowering of calcium crosslinking due to a decrease of calcium level in the cheese texture.The results suggested that the lactic acid metabolism and pH rise play a main part in inducement,and that insolble calcium phosphate accumulates in the cheese surface.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548912000食肉より分離した乳酸球菌が生産するバクテリオシンの抗菌特性3944ENShigetoOkabeJong-SooMokTomomitsuSewakiKeiKataokaMasatoshiIzumimotoTakuMiyamotoTo control the growth of foodborne spoilage bacteria in fermentes meat produncts, 732 strains of lactic acid bacteria were isolated from commercial meats, and their inhibitory activities were investigated by paper disc assay using Staphylococcus aureus IAM 1011 and Listeria monocytogenes VTU 206 as indicator starins. Four starins produced antibacterial substances and one of them showed greater activity against two indicator strains. It was identified as Enterococcus faecium, and it was designed as strain C210. Antibacterial activity was high between the late-logarithmic growth phase and early-stationary growth phase in broth media. Activity in the antibacterial substance was not detectable after treatments with proteolysis enzymes such as pepsin, carboxypeptidase, aminopeptidase, pronase E and proteinase K. The bacteiocin was heat-stable and showed greater antibacterial activity at low pH. The substance showed antibacterial activity against 5 species of lactic acid bacteria in addition to Staphylococcus aureus and Listeria monocytogenes, although it was not active against Gram-negative bacteria. It exhibited bacteriostatic action at pH 4.5, and bactericidal action at pH 6.5 against Listeira monocytogenes as an indicator strain.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02549012001食肉製品の製造工程におけるHACCPシステムによる微生物検査3744ENJaechulLeeMasatoshiIzumimotoTakuMiyamotoMeat product industries have been introduced to HACCP, Hazard Analysis and Critical Control Point, which is internationally recognized as the best method for assuring product safety by controlling potential food safety hazards. The present research was carried out to evaluate the safety of meat production after applying the HACCP system to the manufacturing line of meat products. Factors such as raw meat, the middle product, the final product, the stored product, the equipment and factory workers' conditions were investigated to confirm whether safe meat production is achieved and if an enterprize can maintain such production and marketing. As a result, on one hand, in the case of meat processing, the bacteria in products after cooking were found. Also, no secondary bacteria contamination could be found under good sanitary management of the packaging process. Detection of bacteria in products during storage for 25 days at 4℃ was negligible or even negative. The bacteria
in the equipment and working environment and in the bacteria in the packaging process were at lower levels than in the manufacturing process. The levels ov bacteria and mold from the air in the factory suggested to habe no influence on products. The HACCP system effectively managed the sanitation of the manufacturing process in this factory. Furthermore, education of the workforce, and the sanitary management of tools and materials are constantly necessary in order to maintain product safety.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02549212003食肉タンパク質におよぼすイチジク果実プロテアーゼの基本的性状5356ENChengchunSunMasatoshiIzumimotoTakuMiyamotoKokoroMiyaseThe fundamental properties of fig protease on meat protein were determined and the possibilioty of meat tenderization by this proteolytic enzyme was examined. The amount of liberated peptide from the meat protein increased until one hour of reaction time and because almost constant after taht. Fig protease activity was held by freezing at -80℃ for 7 months. The activities were a little different in 0-8% of salt concentration. On the pH dependency, though activity was higher in the neutral range at pH 6-7 than acidic range, it was almost constant. Optimum temperature was found in higher temperature at 80-90℃. Activity was inhibited with N-ethylmaleimide. The activity of fig 1g was equivalent to the protease of Taka-diastase 10mg. No bitterness was recognized in the meat after treatment with fig homogenate.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-0254 9612007連続咀嚼筋電位の測定と解析5963ENMasatoshiIzumimotoSeiyaHirotsuIchiroNaitoMakikoYoneharaTakuMiyamotoPetrPipek In the palatability of food, texture is a major factor of food quality. The physical shear force value of
meat has been measured. However, quantitative relationship and characterization between shear force value and tenderness as a sensory perception has not been clear. Therefore, a computer system was developed to analyze and to measure the electromyography (EMG) for mastication.<br>
The integral EMG values were almost constant by sequential mastication up to five times. The average of integral EMG values were 63.6 mV with tender meat of pork fillet and 153.8 mV with firm meat of beef round, giving a ratio of 2.4 times. The shear force values of similar samples were 2,300 g and
8,300 g each, and the ratio was 3.6 times. Sensory texture of the subjective feeling was 3ﾝ4 times that corresponded with the shear force value. The integral EMG value could be thought to compress the amount of texture sense.<br>
The integral EMG varied greatly in food, and showed lower value in order of boiled fish surimi, steamed fish paste, pork sausage, konnyaku (devil’s tongue), pork fillet, beef loin, pork ham portion, roast beef, pork loin and beef round. Generally this order reflected the sensory texture of chewing. The deviation of the integral EMG value was smaller than expected, so it has a definite possibility for practical
use.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548011992細胞接合によるラクトース非発酵性Lactobacillus caseiの代謝機能改造の試み139146ENTakuMiyamotoHidetoshiMoritaKohshiNishiokaKeiKataokaラクトース非発酵性Lactobacillus caseiはラクトース発酵能を欠くために,牛乳培地では酸生成がみられず,乳業用乳酸菌として応用する場合,ラタトース発酵性をこの菌株に付与する必要がある.そこで,Lactobacillus casei subsp. caseiのラクトース非発酵性(Lac-株である.34143S(ストレプトマイシン耐性,Strr)および34143P(ペニシリン耐性,Penr)株を分離し,それらを受容菌として液体培地中や寒天培地上での接合法によって,Lac+交配菌の作出を検討した.その結果,受容菌と供与菌Lactobacillus delbrueckii subsp. bulgaricus7235との交配で得られたLac+StrrやLac+Penrの交配菌,Lactobacillus rhamnosus IFO3245とのLac+StrrやLac+Penr株およびStreptococcus salivarius subsp. Thermophilus 18235とのLac+Penr株を3回の繰り返し試験で再現性高く得ることができた.それらの接合頻度は,供与菌当たり,1.1×10-5から1.6×10-2の範囲であり,比較的高い頻度でLac+交配菌の得られる組合せもあった. 得られた交配菌はほとんどが脱脂乳を凝固し,ラクトース発酵性は安定であった.また交配菌の糖類発酵性やその他の性状試験から,受容菌と供与菌にない性質を発現した交配菌や受容菌のもつ性質の一部を欠落した交配菌もあった.しかし形態はいずれも受容菌と同一であった.これらのラクトース発酵性交配菌の出現は,自然突然変異,形質導入および形質転換によるものではなく,受容菌と供与菌の細胞接合によりラクトース発酵性が発現したものと考えられた.またこのラクトース発酵性の発現は,プラスミドの伝達によるものではないと思われた.しかし詳細については今後さらに検討する必要がある。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02545811981全脂大豆乳を強化した発酵乳の製造6573ENTakuMiyamotoJunkoSatoToshitakaNakae全脂大豆乳を強化した発酵乳の製造に関する種々の影響要因を調べ,実用化可能なヨーグルト様食品を製造する目的で本研究を行ったところ,次のような結果を得た. 1) 豆乳･脱脂乳の混合培地では,S. lactis527の酸生成量が他菌に比べて全般的に低い値であった. 豆乳のみの培地では,使用した3種のスターターは酸の生成量が少なく,乳糖を添加することによって酸生成が促進された. 2) 10%豆乳での乳酸菌による酸生成は5%豆乳の場合よりまさっていた. 3) 豆乳培地にクエン酸を添加することによって,L. casei 6のジアセチル生成量が増加した. 4) 脱脂乳に豆乳を加えることで,ヨーグルト様食品のゲル強度が適切となり,多価不飽和脂肪酸を多く含むヨーグルト様食品が得られた. 5) 官能検査で最も良好な豆乳入りヨーグルトはスターターにL. bulgaricus B-1を用い,ショ糖を10%添加し,35℃で18時間培養したものであり,この豆乳入りヨーグルトに香料を加えるとかなり良好なヨーグルト様食品が得られた. 本実験より,豆乳100%のヨーグルト様,チーズ様などの発酵食品を有利に製造するには,豆乳中で顕著な酸生産性,芳香生産性を示す菌株を検索する必要性が示唆された。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02545511980加糖酸乳飲料におけるショ糖とタンパク質の酸分解について1523ENTakuMiyamotoKeiKataokaToshitakaNakae加糖酸乳飲料の長期間保存中におこる褐色化や味覚の変化は,ショ糖の酸分解による転化糖に起因するものと考え,加糖酸乳飲料に類似した各種の条件下でショ糖の酸分解を経時的に観察し,併せてタンパク質の酸分解についても検討を加えた. その結果,次のような結論を得た. 1)モデル系によるショ糖とカゼインの酸分解は,温度の高いほど,また加熱時間や保存時間が長いほど速く進行するる. 温度が一定のときには酸度が高いものほど酸分解が起こりやすい. ショ糖濃度は高いものほど,またカゼイン濃度は低いものほど酸分解が起こりやすい. 2)実際の製品の場合,乳タンパク質の有する緩衝作用のためにモデル系と同じ条件でもそのpHがモデル系よりもやや高く,それだけ酸分解が起こりにくい. 3)製品の品質維持,すなわち褐色化や味覚の変化を防止するためには製造段階において転化糖の含量が多い不純なショ糖を使用したり,グルコースを併用したりせず,良質のショ糖を使用するのが望ましい. また殺菌時間を最小にして殺菌後すみやかに冷却し,保存時は冷蔵することが必要と思われる。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02545211978岡山県の原料乳の乳質について 細菌数検査の部6167ENToshitakaNakaeKeiKataokaTakuMiyamotoKatsushiSegawa前報の岡山県で生産された原料乳の成分的乳質の調査に引きつづき,今回はその細菌学的乳質を調査した. その結果次のような結論を得た. 1)原料乳の細菌学的乳質は,夏季の乳温の上昇とともに低下した. また乳温は細菌数のみならず細菌叢にも影響するものと思われる. 2)細菌数の地域的な差違はほとんど認められなかった. 3)総菌数,生菌数,低温細菌数および耐熱性細菌数の平均値はそれぞれ4.7×106/ml,1.1×106/ml,5.6×104/mlおよび2.7×104/mlであった. 4)63℃,30分,85℃,20分および100℃,10分の加熱処理乳より耐熱性細菌を分離し,その分離菌株の耐熱性を再試験した. それらの分離菌株の中には63℃,30分あるいは85℃,20分の加熱処理に生存するものがあった。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02545111978岡山県の原料乳の乳質について 化学的組成の部5762ENToshitakaNakaeKeiKataokaTakuMiyamotoAkitakaKondo1976年4月より1977年2月までの各月に,岡山県内10地区の原料乳,合計110個の試料を採取し,その化学的組成を調査した. その結果次のような結論を得た. 1)季節的にみると,脂肪は春と夏季が低く,秋と冬季が高い. 乳糖は一般に秋季に低い値であった. 蛋白質および無脂乳固形分は8月に最低値を示す. また無脂乳固形分においては8%未満のものが季節により若干みられた. 2)地域的にみると,特定地区の乳質が他地区に比較して全般的に劣るものがみられた. 3)成分的にみると,PHは6.70〜6.90,酸度は0.13〜0.15%,比重は1.0301〜1.0338,脂肪は3.25〜3.70%,蛋白質は2.95〜3.35%,乳糖は4.20〜4.45%,灰分は0.68〜0.73%そして無脂乳固形分は8.15〜8.75%の範固にあるものが多い. なおpH,酸度,比重,蛋白質,乳糖,灰分および無脂乳固形分の平均値はそれぞれ6.80,0.14%,1.0313,3.39%,3.13%,4.28%,0.68%および8.29%であった. 4)全般的にみると,全国平均と比較して脂肪はほぼ等しく,無脂乳固形分は若干高く,岡山県の原料乳の乳質は全国的にみて標準ないしはそれ以上のものと思われる。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02544811976モンゴルの乳および乳製品の化学的性状について6367ENToshitakaNakaeKeiKataokaTakuMiyamotoモンゴルよりもち帰ることのできた乳汁試料2点,バター1点およびチーズ様製品5点について一般組成,窒素化合物および脂質構成脂肪酸組成を分析し,わが国における市販の乳製品の分析結果と比較検討した. 馬乳の一般組成は牛乳に比べ蛋白質含量が低く乳糖含量が高い. またモンゴル牛の乳汁組成はホルスタイン乳よりも全固形分含量が高い値であった. 一方チーズ様製品の一般組成は水分含量10.03〜16.94%,蛋白質含量13.50〜44.25%,脂肪含量12.62〜54.94%であり種類によりかなりの変動がみられた. また市販のナチュラルチーズの分析結果とかなりの相違がみられたが,これは原料乳と製造方法が異なるためと考えられる. モンゴルチーズの全窒素含量は21.16〜69.36mg/g,水溶性窒素含量は1.27〜9.49mg/gであり,熟成指数は3.0〜15.5の範囲にあった. これらは市販のゴーダチーズに比べ一般にかなり低い値であった. 一方脂質構成脂肪酸については,牛乳と馬乳で構成脂肪酸の種類に相違がみられ,馬乳脂質の脂肪酸組成は牛乳脂質のそれに比較してC4:0とC6:0酸が存在せず,C18:0酸含量が低く,C18:1,C18:2およびC18:3酸の不飽和脂肪酸含量が高い特徴を示した. またバターおよびチーズ様製品の脂質構成脂肪酸組成は牛乳脂質の脂肪酸組成と本質的なちがいはみられなかった。No potential conflict of interest relevant to this article was reported.