Studies on cell grouth and aminc acid requirement of rumen fungi

本研究旨在阐明瘤胃厌氧真菌生长所需的氨基酸，有助于改进瘤胃厌氧真菌的培养，更好地了解瘤胃微生物生态位。用含10种必需氨基酸(10EAA)和8种非必需氨基酸(8NEAA)或两者同时添加(18AA)的补充剂，研究了绵羊瘤胃Neocallimastix sp.N13的氨基酸需要量。虽然该真菌可以在以硫酸铵为唯一氮源的培养基中生长，但氨基酸的补充，特别是18AA极大地促进了真菌的生长。从18AA中去掉含硫氨基酸(SCAA)显著降低了促生长作用，部分用硫化物而不是硫酸盐代替了SCAA。与添加18AA相比，去掉芳香族、支链、酸性、脂肪族和羟基氨基酸，以及Pro单独或组合，都在一定程度上抑制了真菌的生长。补充3种氨基酸(亮氨酸、蛋氨酸和组氨酸)对真菌有很强的刺激作用，而另一种组合(谷氨酸、蛋氨酸和丝氨酸)则无效。青霉菌的生长。18AA和8NEAA对瘤胃非优势K1的生长也有促进作用，但10EAA不能促进K1的生长。

This study is aimed at elucidating amino acid requirement of rumen anaerobic fungi for their growth, which could contribute to improved culturing of this organisms and better understanding of their niches in the rumen microbial ecosystem. Amino acid requirements of Neocallimastix sp.N13 isolated from sheep rumen were studied with supplements containing 10 essential amino acids (10EAA) or 8 non-essential aminoacids (8NEAA) , or both (18AA). Although the fungus could grow in a medium containing ammonium sulphate as a sole source of nitrogen, amino acid supplement, especially 18AA greatly stimulated fungal growth. Omission of sulphur containing amino acids (SCAA) from 18AA reduced markedly the growth-stimulating effect, and sulphide, but not sulphate, substituted for SCAA partly. Omission of aromatic, branched chain, acidic, aliphatic, and hydroxy amino acids, and proline, singly or in combination, all reduced fungal growth in some degree as compared with 18AA supplement. A 3 amino acids (leucine, methionine, and histidine) supplement was a potent stimulator for the fungus, whereas the other combination (glutamic acid, methionine, and serine) , known to be potent for Neocallimastix patriciarum was ineffective. Growth of Caecomyces sp. K1 less dominant in the rumen was also stimulated with 18AA and 8NEAA,but not with 10EAA.These results suggest that requirements of amino acids for rumen fungal growth may differ among genera, species and even strains.