Katsuya Okuuchi's scientific contributions

Publications (6)

Article
本研究は,トリプトファン(Trp),インドールピルビン酸(IPA)およびインドール酢酸(IAA)を基質として,ルーメン細菌(B系),繊毛虫(P系)およびそれらの共存系(BP系)によるTrp,スカトール(Skt)および関連化合物の生成におよぼすサリノマイシン(SL)(5μg/ml)の影響を検討することを目的とした.ルーメン微生物は,1日2回アルファルファキューブと濃厚飼料を給与しているフィスチュラ装着山羊から採取した.12時間培養後,SL無添加のBP系およびB系におけるIPAからの遊離のTrp生成量は,それぞれ,0.7および2.2%と低い値であったが,SLを添加すると,それぞれ,58.9および16.4倍に増加した.P系におけるIPAからの遊離Trpの生成量はSL無添加でも35.3%と高かったが...
Article
In vitroでのルーメンプロトゾア(P懸濁液),ルーメンバクテリア(B懸濁液)およびそれらの混合懸濁液(BP懸濁液)によるL-トリプトファン(Trp)からのインドール(Ind)およびスカトール(Skt)の生成を確認するとともに,これらの微生物懸濁液によるTrpからのIndおよびSkt生成に及ぼすサリノマイシン(SL)の影響を検討する目的で本研究を計画した.また,同時に,IndおよびSktがプロトゾアの生存および上記の各種微生物懸濁液中における揮発性脂肪酸(VFA)の生成に及ぼす影響も検討した.ルーメン微生物は,フィスチュラ装着山羊から採取した.その結果,P懸濁液は,12時間の培養中にTrpからIndのみを生成した.SLはP懸濁液におけるIndの生成を促進した.BおよびBP懸濁液中では,と...

Citations

... Investigation of tryptophan metabolism by mixed rumen protozoa, bacteria and their combination has enabled the identification of the relative contribution of these micro organisms to the production of skatole.Mohammed et al. (2003) andOkuuchi et al. (1993) have demonstrated that skatole is fo rmed solely by rumen bacteria and not by protozoa, however the interaction of the two micro-organisms in mixed cultures has relevance to the in vivo production of skatole from tryptophan in grazing ruminants.Okuuchi et al. (1993) fo und that rumen protozoa have an excellent ability to transaminate indolepyruvic acid to yield microbial tryptophan thus stimulating the bacterial production of indoleacetic acid and skatole.Mohammed et al. (2003) reported that 43% of tryptophan was converted to skatole in mixed bacterial and protozoal cultures after 24 hours of incubation. This is close to the value of 39% conversion reported byYokoyama and Carlson (1974) during the 24 hour incubation of radio labelled tryptophan. ...
... Deamination determines the rate of ruminal amino acid degradation (Annison et al., 1959;Lewis, 1962). SL has been shown to decrease amino acid breakdown (Hoshino et al., 1992;Okuuchi et al., 1993), and this may be due to the inhibitory effect of deamination as has been observed with other ionophores (Hino and Russell, 1985;Newbold et al., 1990;Russell and Martin, 1984;Van Nevel and Demeyer, 1977;Wallace et al., 1981). In the case of tryptophan metabolism, Okuuchi et al. (1993) reported that tryptophan production from indolepyruvic acid in all the rumen bacterial and protozoal suspensions was greatly enhanced by SL, but skatole and indole production from tryptophan by SL were completely inhibited in the rumen bacterial suspensions. ...
... On the other hand, there have been some studies concerning the catabolic pathways of some amino acids. Of the aromatic amino acids, the tryptophan metabolism by rumen microorganisms has been investigated in detail (Okuuchi et al., 1993a(Okuuchi et al., , 1993bOnodera et al., 1992). Phenylalanine (Phe) has also been shown to be deaminated and converted to phenylacetic acid (PAA) by rumen bacteria (Van Den Hende et al., 1964), rumen protozoa Entodinium cau-datum (Coleman, 1967) and combination of rumen microorganisms (Martin, 1973;Patton and Kesler,1967). ...
... The lowering protozoal counts in ruminal fluid could be due to the highest NH 3 -N concentration, which has been reported by Kanjanapruthipong and Leng [20]. Protozoa did not utilize urea as a N source and amino acids are needed for protozoal synthesis [21]. This might potentially decrease protozoa synthesis in the rumen [20]. ...