Kenkichi Oba

The filamentous fungusmortierella alpina, high in arachidonic acid

Arachidonic acid is not available readily, although it is widely distributed in animal tissue. We found that in some strains ofMortierella alpina, arachidonic acid accounted for 68.5–78.8% of the total fatty acids. This is more than twice the arachidonic acid content of any organism previously reported. The content of arachidonic acid per dry cell weight was about 25%. Our findings offer a method for the efficient isolation of arachidonic acid in large amounts.

A simple method for production of arachidonic acid byMortierella alpina

SummaryA filamentous fungus,Mortierella alpina was incubated aerobically on a medium made from potato paste and dextrose at 20 °C for 20 days. The yield of arachidonic acid reached 11.8 g/kg medium, which is more than 10 times higher than that by any other method reported previously. The highest content of the acid was 67.4% of the total fatty acids.

Biodegradation of 2-sulfonatofatty acid methyl ester (α-SFMe)

The biodegradation pathways of α-SFMe were determined based on changes in the chemical structure of C 14 -α-SFMe by IR, NMR and HPLC analyses in the MITI test. Microbial attack on the surfactant structure was initiated by ω-oxidation to form a carboxyl group and continued with β-oxidation, causing the removal of two carbons at a time, to form a temporary intermediate, monomethyl α-sulfosuccinate. Degradation subsequently occurred by desulfonation

A Simplified Disc Technique for Quantitating Mouse DNA, RNA and Protein Synthesis: Circadian Rhythms

1) A modified disc technique has been developed for quantitating DNA, RNA and protein synthesis in epidermal hairless mouse skin and utilized in examining circadian rhythms. 2) The modified epidermal assay for DNA synthesis, utilizing dissolution of epidermis before scintillation counting, yields three times the specific activity than does the original disc technique. The modified disc technique also gives satisfactory results for RNA and protein synthesis. 3) The incorporation of 3H‐thymidine (3H‐TdR) into DNA was highest from 23:00 to 03:00. RNA synthesis, as measured by 3H‐uridine (3H‐UR) incorporation, and protein synthesis, as measured by 3H‐leucine (3H‐Leu) and 14C‐histidine (14C‐His) incorporation, did not show any obvious circadian rhythm.

Biodegradation of 2-sulfonato fatty acid methyl ester (α-SFMe) : identification of microorganisms isolated from activated sludge and their capability for degrading α-SFMe

Three bacterial strains, A, B and C, were isolated from activated sludge as 2-sulfonato-fatty-acid-methyl-ester (α-SFMe)-degrading microorganisms. From the results of morphological, physiological and biochemical studies, and analyses of 16S rRNA gene sequences, isolate A was identified as Agrobacterium tumefaciens while B and C were Pseudomonas putida, respectively. To demonstrate their capability for the ultimate biodegradation of α-SFMe, the degradation kinetics have been investigated using C14-α-SFMe and 2-14C-labeled C16-α-SFMe. The biodegradation was determined by measuring dissolved organic carbon (DOC) and released SO42−, in the shake-culture test, and evolved 14CO2 in the modified Organisation for Economic Co-operation and Development (OECD) test. In the shake culture test with C14-α-SFMe, DOC removal was progressive throughout the test. Liberation of inorganic sulfate started after DOC removal and then rapidly increased. During the 14CO2 evolution tests, the mineralization of radiolabeled carbon started quickly and reached about 80% of the initially added radioactivity at the end of the tests. The results obtained indicated that all of the isolates had the capability for ultimately degrading α-SFMe through the oxidation of the alkyl carbons and desulfonation (cleavage of the C-S linkage).

Nutritive evaluation of fish protein hydrolysate.

脱脂イワシ魚粉の酵素加水分解物 (FPH) について栄養価を検討して以下の結果を得た。1) アミノ酸組成からみると, FPHは脱脂イワシ魚粉に比べてトリブトファンの比率が若干低下するものの, 全体的に加水分解によるアミノ酸組成の変動は少なかった。アミノ酸スコアはFAO/WHO (1973) のパターンに対して, 100であり, もとの魚粉に遜色のない良質なタンパク素材であることが示された。2) 成長期ラットを用いた栄養試験の結果, FPHは増体重5.3g/日, タンパク効率 (PER) 3.2, 正味タンパク効率 (NPR) 5.2, 生物価 (BV) 86, 真の消化率 (TD) 99%, 正味タンパク利用率 (NPU) 85の値を示した。FPHのタンパク栄養価はアミノ酸混合物には若干及ばないが, 脱脂イワシ魚粉とほぼ同等, カゼインに比べるとやや上回るレベルであり, 非常に優れていることが確認された。3) さらに, 上記栄養試験に用いたラットについて血液成分12項目, 肝臓重量および肝脂質量を測定した結果, FPHは他の供試品とともにほぼ正常値の範囲と考えられ, これらに対する特異的な影響はないものと思われた。