環境ストレス下における納豆菌の胞子形成  [in Japanese] Spore Formation Caused by Environmental Stress in Natto Bacilli  [in Japanese]

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Abstract

納豆菌の栄養細胞から胞子のみを分離し,胞子懸濁液を製造することは新規納豆菌の実用化のために必須の条件である.Mn<SUP>2+</SUP>添加,冷蔵・乾燥処理の環境ストレスをかけることによって市販納豆菌から分離した<I>B. subtilis(natto)</I>KFP 2のスターター化条件を調べた.<BR>1.市販納豆菌を納豆工場16箇所から集め,胞子割合を測定した結果,値の低い2点を除くと平均94.0%であった.<BR>2.0.1mmol/lMn<SUP>2+</SUP>をNBP平板培地に添加することによって<I>B. subtilis(natto)</I> KFP 2(スターターBより分離)の胞子形成が促進されることを見いだした.最適Mn<SUP>2+</SUP>濃度は0.1mmol/lであった.<BR>3.KFP 2のスターター化を検討した結果,Mn<SUP>2+</SUP>添加培地で培養後菌液を冷蔵,完全に乾燥することによって収率97.3%で胞子を得ることができた.<BR>4.同様の方法で,市販納豆菌から分離したKFP 1, KFP 4と研究室保存の納豆菌KFP 419, KFP 827, KFP 828についてもスターター化した結果,KFP 4以外の菌では胞子割合90%以上を達成した.KFP 4では,71.4%と胞子割合が低かった.<BR>5.調製したKFP 2(スターターBより単離)の胞子懸濁液で小規模の納豆製造を行って官能検査を行った結果,糸引きはスターターBで製造した納豆よりもよく,菌の被り,香りでは同等と評価された.硬さ,うま味においてはやや劣るという評価であった.

The formation of spores by vegetative cells of natto bacilli, as occurs in the production of natto starter cultures, was investigated by subjecting the natto bacilli to environmental stress. This is an essential component of industrial natto production. We collected natto starter suspensions from sixteen natto factories and measured their spore ratios (%) according to the following equation : (spore/(spore+vegetative cell) ×100). The mean spore ratio was 94.0%, apart from two samples whose spore ratios were particularly low. The highest spore ratio, 97.3%, was achieved when stationary cells of <I>Bacillus subtilis (natto)</I> KFP 2, a commercial isolate, were cultured in NBP (NaCl-beef extract-phytone peptone) agar containing 0.1 mmol/l Mn<SUP>2+</SUP>, refrigerated, mixed with sea sand and dried under vacuum. We also induced sporulation and calculated spore ratios in KFP 1 strains isolated from commercial natto starter, and KFP 419, KFP 827 and KFP 828 strains from a culture collection held by our laboratory. Although KFP 4, one of the commercial natto strains, showed spore ratios as low as 71.4%, the ratios in the other strains exceeded 90%. Using spores prepared from KFP 2, we produced natto in a scaled-down version of the natto production process and used organoleptic testing to compare our product with natto made using commercial natto starter. Compared with natto made from commercial starter, the scores of our natto were higher for stickiness, the same for appearance and odor, and slightly lower for toughness and <I>umami.</I> Our new natto starter may be strongly recommended for use in commercial natto production.

Journal

  • Nippon Shokuhin Kagaku Kogaku Kaishi

    Nippon Shokuhin Kagaku Kogaku Kaishi 53(3), 165-171, 2006-03-15

    Japanese Society for Food Science and Technology

References:  16

Cited by:  3

Codes

  • NII Article ID (NAID)
    10017970097
  • NII NACSIS-CAT ID (NCID)
    AN10467499
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    1341027X
  • NDL Article ID
    7848891
  • NDL Source Classification
    ZP34(科学技術--食品工学・工業)
  • NDL Call No.
    Z17-126
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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