Phage resistance and altered growth habit in a strain of Streptococcus bovis.

Bacteriophage (phi Sb01) of Streptococcus bovis, isolated from pooled rumen fluid of cattle, was a small siphovirus of morphotype B1. It contained double-stranded DNA of length 30.9 kb, which was digested by the restriction endonucleases, EcoRI, HindIII, and PvuII.

Morphology of three polycentric rumen fungi and description of a procedure for the induction of zoosporogenesis and release of zoospores in cultures.

Three polycentric rumen fungi, LL, LC2 and Ruminomyces elegans (C2), isolated from the rumen of cattle were grown in six culture media. LL and LC2 were morphologically similar. Their characteristics resembled those of Orpinomyces and Neocallimastix joyonii, and they grew well and produced sporangia after 3-4 d growth in all the media.

Inducible bacteriophages from ruminal bacteria.

The incidence of temperate bacteriophage in a wide range of ruminal bacteria was investigated by means of induction with mitomycin C. Supernatant liquid from treated cultures was examined for phagelike particles by using transmission electron microscopy. Of 38 ruminal bacteria studied, nine organisms (23.

The isolation and comparison of cellulase genes from two strains of Ruminococcus albus.

Endo-1,4-beta-glucanase genes have been cloned from two strains of Ruminococcus albus recently isolated in this laboratory. Although the strains were phenotypically similar, cross-hybridization studies between them showed significant genetic differences, with only 20% of the genome forming DNA heteroduplexes. Heteroduplexes displayed an average dissociation temperature 9 degrees C lower than that of the homoduplex.

Biology of gut anaerobic fungi.

The obligately anaerobic nature of the gut indigenous fungi distinguishes them from other fungi. They are distributed widely in large herbivores, both in the foregut of ruminant-like animals and in the hindgut of hindgut fermenters. Comparative studies indicate that a capacious organ of fermentative digestion is required for their development.

Morphological diversity of ruminal bacteriophages from sheep and cattle.

Large numbers of bacteriophages (2 x 10(7) to 1 x 10(8)/ml) were present in ruminal fluid from sheep and cattle. Twenty-six distinct types were identified and placed in three morphological groups; several phages possessed unusual structural features. The large numbers and diversity of phages observed indicates a possible role in bacterial lysis and hence in the population dynamics of the ruminal bacteria.

Ultrastructural description of a new chytrid genus of caecum anaerobe, Caecomyces equi gen. nov., sp. nov., assigned to the Neocallimasticaceae.

Vegetative and reproductive stages of Caecomyces equi gen. nov., sp.

Basal body loss during fungal zoospore encystment: evidence against centriole autonomy.

The controversial question of the possible autonomy of centrioles, as shown by the persistence of all or part of them in the generative cell line throughout the life cycle of organisms, remains unresolved. All previous reports on shedding or withdrawal of cilia and flagella showed that their basal bodies (= centrioles) were retained in the cells where they may, or may not, subsequently disassemble. We show that in the fungus Neocallimastix sp.

Glycosidases of the rumen anaerobic fungus Neocallimastix frontalis grown on cellulosic substrates.

The rumen anaerobic fungus Neocallimastix frontalis was grown on cellulosic substrates, and the cellular distribution and types of glycosidases produced by the organism were studied. Fungal cultures were fractionated into extracellular, insoluble (membrane), and intracellular fractions and assayed for glycosidase activity by using Avicel, carboxymethylcellulose, xylan, starch, polygalacturonic acid, and the p-nitrophenyl derivatives of galactose, glucose, and xylose as substrates. Enzymic activity was highest in the extracellular fraction; however, the membrane fraction also displayed appreciable activity.

Fermentation of Cellulose to Methane and Carbon Dioxide by a Rumen Anaerobic Fungus in a Triculture with Methanobrevibacter sp. Strain RA1 and Methanosarcina barkeri.

The fermentation of cellulose by a rumen anaerobic fungus in the presence of Methanobrevibacter sp. strain RA1 and Methanosarcina barkeri strain 227 resulted in the formation of 2 mol each of methane and carbon dioxide per mol of hexose fermented. Coculture of the fungus with either Methanobrevibacter sp.

Cellulose fermentation by a rumen anaerobic fungus in both the absence and the presence of rumen methanogens.

The fermentation of cellulose by an ovine rumen anaerobic fungus in the absence and presence of rumen methanogens is described. In the monoculture, moles of product as a percentage of the moles of hexose fermented were: acetate, 72.7; carbon dioxide, 37.

Rumen anaerobic fungi of cattle and sheep.

Plant fragments obtained from natural rumen digesta of fistulated cattle and sheep were examined by scanning electron microscopy. Various plant materials suspended in the rumen for different times were examined likewise. By 2 h large numbers of phycomycetous fungal zoospores were found attached to fibrous plant fragments, particularly vascular tissues.

The rumen ciliate epidinium in primary degradation of plant tissues.

Pieces of lucerne stem suspended in a sheep rumen in nylon bags were removed after different time intervals and examined by scanning electron microscopy. By 15 min large numbers of the ciliate protozoan Epidinium Crawley were attached to damaged areas of the stem, although a complex protozoal fauna was present in the rumen contents. Highest concentrations were on cortex and phloem tissues, with densely packed protozoa forming a complete ring around the transversely cut end of the stem between the epidermis and the vascular cylinder.

Attachment of the ciliate Epidinium Crawley to plant fragments in the sheep rumen.

High concentrations of the ciliate Epidinium Crawley are associated with damaged regions of fresh plant material undergoing digestion in the sheep rumen. This finding supports that postulate that sequestration in the rumen explains the low rate of passage of protozoa despite the high flow rate of liquid from the rumen. The maintenance of Epidinium in the rumen, despite their slow growth rate, is also explained.

Scanning electron microscope study of bacteria associated with the rumen epithelium of sheep.

Examination of the rumen epithelium of sheep by scanning electron microscopy revealed bacteria associated with the epithelial surface. Comparison of epithelial surfaces from 10 sheep revealed areas that were consistently densely covered with bacteria and other areas where the cover was consistently light. The bacterial populations were frequently of mixed morphological types, but areas populated with a single type were also observed.

Formate as an intermediate in the bovine rumen fermentation.

An average of 11 (range, 2 to 47) mumoles of formate per g per hr was produced and used in whole bovine rumen contents incubated in vitro, as calculated from the product of the specific turnover rate constant, k, times the concentration of intercellular formate. The latter varied between 5 and 26 (average, 12) nmoles/g. The concentration of formate in the total rumen contents was as much as 1,000 times greater, presumably owing to formate within the microbial cells.

Ruminant-like digestion of the langur monkey.

The adaptation of langur monkeys to a laboratory environment has made possible a detailed investigation of their digestive physiology. The diverticular form of the langur stomach permits a bacterial fermentation of the leafy diet, which results in important contributions to the nutrition of these primates. The demonstration of a ruminant-like digestion in langurs extends the known taxonomic distribution of this digestive adaptation.

Inhibition of rumen methanogenesis by methane analogues.

Extremely low concentrations of chloroform and carbon tetrachloride and somewhat larger concentrations of methylene chloride inhibited the formation of methane by the rumen microbiota in the presence or absence of added substrate. The accumulation of hydrogen at these low concentrations indicates a selective inhibition of methanogenesis. Presumably, these inhibitors affect one or more of the reactions by which methane is formed from hydrogen and carbon dioxide.