1986年5月上旬から1987年5月下旬にかけて, 宮崎県内の河川水から病原大腸菌の分離を試みた. その結果, 分離した大腸菌158株のうち病原大腸菌の血清に型別されたものは10株 (6.3%) であった. その内訳は毒素原性大腸菌 (Enterotoxigenic E. coli: ETEC) 該当血清型O159: K⁺に型別されたもの5株, 病原性大腸菌 (Enteropathogenic E. coli: EPEC) 該当血清型のO127a: K63型のもの1株, O128: K67型のもの3株, それに細胞侵入性大腸菌 (Enteroinvasive E. coli: EIEC) 該当血清型のO112ac: K66型の1株であった. これら分離株の生物学的性状についてはO159: K⁺に型別された5株はいずれもエンテロトキシン (LT, ST) を産生せず, Colonization Factor Antigens (CFA) 保有時のHAパターンIまたはII型を示さなかった. しかし, EPEC該当血清型のO127a: K63とO128: K67の4株はすべてHeLa細胞への付着試験でマンノース抵抗性の限局した付着を示した. この現象はSCALETSKYらの提案しているEPECの特異的付着パターンに類似した.

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感染型食中毒起因菌である腸炎ビブリオの弱酸性下における生存に及ぼす消化酵素ペプシンの影響, 及び微アルカリ性下における本菌の酸損傷からの回復・増殖に及ぼすトリプシンの影響を検討した結果, 次のような成績が得られた.
1. ペプシンはpH4～5において酸損傷菌に作用を及ぼし, その死滅を促進させた.
2. トリプシンはpH8付近において, コール酸との共存下においても, 酸損傷菌に阻害作用を発揮せず, 酸損傷からの回復・増殖を許した.

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焼竹輪およびその原料となるスケトウ冷凍すり身の生菌数測定, また前回, 多少相関係数の低かった乳酸菌飲料の乳酸菌数測定において, Bactometer法を応用するに必要な諸条件を検討した.
スケトウ冷凍すり身89例および焼竹輪56例の生菌数測定におけるBactometer法と公定法の相関係数は, それぞれ0.86, 0.82でまずまずの相関が得られた.
乳酸菌飲料の乳酸菌数測定において, Bactometer法ではLM培地を使用し, ブランドごとに測定コードを変えることで, 現在わが国で市販されている20ブランドのBactometerによる乳酸菌数の測定が可能になることが明らかになった.

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厚生省が公表した畜水産食品の微生物規格案 (昭和62年) の「液卵の微生物規格」にもとづき, 一液卵製造施設の未殺菌液卵及び殺菌液卵の細菌数, 大腸菌群, サルモネラ汚染状況を調査した. 本調査においてサルモネラの汚染等が著しかったので, 工程中における汚染防止と汚染源追求の目的で, 工程別のふきとり検査や原料卵等の検査を行った. その結果, 原料卵の卵殻が汚染源として重要であり, 洗卵時の塩素消毒 (200ppm) が汚染除去に有効であることが判明した. 原料卵の消毒や施設内のパイプライン等の洗浄, 消毒の徹底を指導した後の検査では, 液卵の汚染を大幅に減少させることができた.
また液卵ヘサルモネラ (3血清型), 病原大腸菌 (4血清型) を実験的に接種し, 25℃, 5℃, -20℃における各菌の増殖, 生存について検討したところ, 卵黄は両菌種の増殖に適していたが, 卵白は両菌種の増殖を抑制した. なお, 液卵中の両菌種は凍結によっても菌数の減少はほとんどみられないことがわかった.

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Potassium sorbate (PS), sodium nitrate (SN), condensed phosphate, sodium chloride, and glycine, added singly or in combinations, to Brain Heart Infusion (BHI) at different pH values were examined for the inhibitory effects on growth and enterotoxin A production of Staphylococcus aureus (S. aureus) in inoculum sizes of 10³ and 10⁶ cells/ml and at 35°C. Only a slight inhibition of S. aureus was observed at pH 5.0 and aw0.99, and it decreased as pH was raised to 6.0 and 7.0.
Some inhibitory effects of PS were seen at 1, 000 ppm and 2, 000 ppm inoculated with 10³ and 10⁶ cells/ml of S. aureus at pH 5.0, respectively and 20, 000 ppm at pH 6.0 and 40, 000 ppm at pH 7.0 and aw 0.97 on the both inocula.
Growth and enterotoxin production of S. aureus were inhibited by SN of 75 ppm with the inoculum of either size at pH 5.0, but was not controlled by the addition of 750 ppm SN at pH 6.0.
Sodium acid pyrophosphate (SAPP) at 4, 000 ppm was not effective on S. aureus at any pH, but sodium ultrapolyphosphate (SUPP) and sodium metaphosphate (SMP) at 4, 000 ppm were very effective on the both inocula at pH 7.0. Sodium tripolyphosphate (STPP) and a 2: 1 mixture of STPP and SAPP (TPAP) at 4, 000 ppm inhibited growth and enterotoxin production of S. aureus on the inoculum of either size at pH 5.0, and on the inoculum of 10³ cells/ml at pH 6.0, respectively. STPP at 2, 000 ppm was effective on the inoculum of 10³ cells/ml of S. aureus.
The combination of 200 ppm of PS and 35 ppm of SN at pH 5.0 and 2, 000 ppm of PS and 35 ppm of SN at pH 5.5 exhibited a synergistic activity on the both inoculums of S. aureus.
The combination of 75 ppm of SN and 2, 000 ppm or 1, 000 ppm of TPAP at pH 6.0 also showed clear inhibition on the both inocula and on the inoculum of 10³cells/ml of S. aureus, respectively. At pH 6.5, 75 ppm of SN and 4, 000 ppm of TPAP showed a effective inhibition on the inoculum of either size.
The combination of three agents, 2, 000 ppm of TPAP, 75 ppm of SN, and 2, 000 ppm of PS showed a high effect more rapidly in about 12 hours than without PS at pH 6 .0 on S. aureus. When NaCl was further supplemented, growth was slightly inhibited, especially by the addition of 3.5% NaCl that has got up speed about 8 and 16 hours when inoculated with 10³ and 10⁶ cells/ml of S. aureus, respectively.
At pH 6.5 and aw 0.95, growth and enterotoxin production of S. aureus in BHI inoculated with 10³cells/ml were completely inhibited by the combination of 3, 000 ppm of TPAP, 75 ppm of SN, 1, 000 ppm of PS, 3.5% of NaCl and 1% of glycine after 72 hours of incubation.

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A synthetic medium for the production of trichothecene mycotoxins by Fusarium species has been developed. Fusarium sporotrichioides F-135 strain was inoculated in a synthetic medium (SSA) containing sucrose, salts, asparagine and Ca-panthothenate. In 14 days of still incubation at 25°C, the organisms produced 2, 265μg/ml of T-2 toxin and 420μg/ml of diacetoxyscirpenol. The medium also supported production of a large amount of fusarenone X, nivalenol, neosolaniol, butenolide and moniformin by the organisms. The results indicate that the SSA medium appears to be suitable for production of trichothecens and other mycotoxins by Fusarium species.
The medium consists of the following components: sucrose 200g, Asparagine 10g, Capanthothenate 0.01g, NaNO₃ 1g, MgSO₄·7H₂O 1g, KH₂PO₄ 0.75g, ZnSO₄·7H₂O 0.1g, FeSO₄·7H₂O 0.01g, MnCl₂·4H₂O 0.001g, CuSO₄·5H₂O 0.001g, Co (NO₃) ₂·6H₂O 0.0001g, NaMoO₄·2H₂O 0.001g, NiCl₂·6H₂O 0.001g, Na₂B₄O₇ 0.001g and distilled water 1, 000ml.

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The effect of low pH on survival and growth of C. jejuni and C. coli were studied in Brain Heart Infusion broth acidified with hydrochloric, acetic, citric, maleic, succinic, malic or lactic acid. The survival and growth of C. jejuni and C. coli at low pH depended in the type of acid present. The cells of C. jejuni and C. coli died within 3 h at pH 4.0 adjusted with each organic acid at either 10 or 25°C. In broth adjusted to pH 5.0 with lactic or acetic acid, the cells decreased in number within 24 h and 48 h, respectively, at 10°C. At pH 5.0 adjusted with other acids and at 10°C, the cells survived over 48 h. The cells of C. jejuni held for 48 h at 25°C decreased in number in broth adjusted to pH 5.5 with any organic acid. C. jejuni and C. coli grew at pH 5.7 acidified with hydrochloric, citric, succinic, malic or lactic acid; however they failed to grow at the same pH value acidified with acetic or malic acid. The lowest pH at which C. jejuni and C. coli grew in these acids was 6.5.

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