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At least 19 recordsLinked to original sources
PubMed2006

Lactic acid bacteria inducing a weak interleukin-12 and tumor necrosis factor alpha response in human dendritic cells inhibit strongly stimulating lactic acid bacteria but act synergistically with gram-negative bacteria.

The development and maintenance of immune homeostasis indispensably depend on signals from the gut flora. Lactic acid bacteria (LAB), which are gram-positive (G+) organisms, are plausible significant players and have received much attention. Gram-negative (G-) commensals, such as members of the family Enterobacteriaceae, may, however, be immunomodulators that are as important as G+ organisms but tend to be overlooked. Dendritic cells (DCs) are crucial immune regulators, and therefore, the present study aimed at investigating differences among human gut flora-derived LAB and G- bacteria in their patterns of DC polarization. Human monocyte-derived DCs were exposed to UV-killed bacteria, and cytokine secretion and surface marker expression were analyzed. Profound differences in the DC polarization patterns were found among the strains. While strains of LAB varied greatly in their capacity to induce interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-alpha), G- strains were consistently weak IL-12 and TNF-alpha inducers. All strains induced significant amounts of IL-10, but G- bacteria were far more potent IL-10 inducers than LAB. Interestingly, we found that when weakly IL-12- and TNF-alpha-inducing LAB and strong IL-12- and TNF-alpha-inducing LAB were mixed, the weakly IL-12- and TNF-alpha-inducing LAB efficiently inhibited otherwise strong IL-12- and TNF-alpha-inducing LAB, yet when weakly IL-12- and TNF-alpha-inducing LAB were mixed with G- bacteria, they synergistically induced IL-12 and TNF-alpha. Furthermore, strong IL-12- and TNF-alpha-inducing LAB efficiently up-regulated surface markers (CD40, CD83, CD86, and HLA-DR), which were inhibited by weakly IL-12- and TNF-alpha-inducing LAB. All G- bacteria potently up-regulated surface markers; however, these markers were not inhibited by weakly IL-12- and TNF-alpha-inducing LAB. These much divergent DC stimulation patterns among intestinal bacteria, which encompass both antagonistic and synergistic relationships, support the growing evidence that the composition of the gut flora affects immune regulation and that compositional imbalances may be involved in disease etiology.

Bifidobacterium↗
PubMed2004

Seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria.

Based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the Bacteria. However, members of the two taxa that comprise this group, the green sulfur bacteria (Chlorobi) and the filamentous anoxygenic phototrophic bacteria ("Chloroflexales"), are otherwise quite different, both physiologically and phylogenetically. This review summarizes how genome sequence information facilitated studies of the biosynthesis and function of the photosynthetic apparatus and the oxidation of inorganic sulfur compounds in two model organisms that represent these taxa, Chlorobium tepidum and Chloroflexus aurantiacus. The genes involved in bacteriochlorophyll (BChl) c and carotenoid biosynthesis in these two organisms were identified by sequence homology with known BChl a and carotenoid biosynthesis enzymes, gene cluster analysis in Cfx. aurantiacus, and gene inactivation studies in Chl. tepidum. Based on these results, BChl a and BChl c biosynthesis is similar in the two organisms, whereas carotenoid biosynthesis differs significantly. In agreement with its facultative anaerobic nature, Cfx. aurantiacus in some cases apparently produces structurally different enzymes for heme and BChl biosynthesis, in which one enzyme functions under anoxic conditions and the other performs the same reaction under oxic conditions. The Chl. tepidum mutants produced with modified BChl c and carotenoid species also allow the functions of these pigments to be studied in vivo.

Bacterial Proteins↗
PubMed1999

Growth rates of mesophilic bacteria, aerobic psychrotrophic bacteria, and lactic acid bacteria in low-dose-irradiated pork.

Frozen pork patties, thawed overnight at 0 degrees C or temperature abused through storage at 15 degrees C for 24 h, were packaged using both vacuum and air packaging methods. Immediately after packaging, both sets of patties were irradiated at 0, 0.5, 1, and 2 kGy. All the samples were stored at 2 degrees C and were analyzed for populations of mesophilic, psychrotrophic, and lactic acid bacteria every 3 days for 30 days. By using a mesophilic population of 10(7) cells/g as a criteria for spoilage, fresh pork patties receiving a dose of 0 kGy had shelf lives of 11 and 16 days with air and vacuum packaging methods, respectively, whereas temperature-abused patties had a shelf life of 7 days with both air and vacuum packaging methods. Both fresh and abused patties that received a dose of 2 kGy had shelf lives that were greater than 30 days at 2 degrees C with both air and vacuum packaging methods. Descriptive models based on the Gompertz equation for mesophilic, psychrotrophic, and lactic acid bacteria were developed, and the generation time and lag-phase duration for each bacterial population were calculated.

Animals↗
PubMed2003

Sponge-associated bacteria: general overview and special aspects of bacteria associated with Halichondria panicea.

Increasing evidence is accumulating that highlights the important role of bacteria in bacteria-sponge associations. It appears to be equally important to analyse the specific association of bacteria with sponges, to realise the biological function of biologically active substances produced by sponge-associated bacteria, and to consider the relationship between bacteria and sponges in the search for new pharmaceutical products. In this chapter the current knowledge on bacteria-sponge associations is briefly reviewed. Results are summarised that were obtained by three major methodological approaches: (1) classical microscope observations, (2) investigations attempting to characterise sponge-associated bacteria by describing pure culture isolates, and (3) the rapidly growing evidence from genetic analyses of sponge-associated bacteria. Special emphasis is given to the evidence of possible symbiotic interactions between bacteria and sponges and to the synthesis of natural products by bacteria isolated from or associated with marine sponges. Case studies including morphological and genetic studies together with results from pure culture studies have been performed with bacteria from the sponges Rhodopaloeides odorabile, Aplysina cavernicola, and Halichondria panicea. In addition, new results on bacteria associated with Halichondria panicea are also presented.

Animals↗
PubMed2005

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2003 and March 2004].

Tendency of isolated bacteria from infections in general surgery during the period from April 2003 to March 2004 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 455 strains including 14 strains of Candida spp. were isolated from 191(75.2%) of 254 patients with surgical infections. Two hundred and thirty-nine strains were isolated from primary infections, and 216 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-positive bacteria and aerobic Gram-negative bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. The isolation rate of aerobic Gram-positive bacteria, such as Enterococcus spp. and Staphylococcus aureus were higher from both types of infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae, Enterobacter cloacae and Pseudomonas aeruginosa in this order, and from postoperative infections, E. coli was the most predominantly isolated, followed by P. aeruginosa, E. cloacae, and K. pneumoniae. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. The isolation rate of anaerobic Gram-positive bacteria from primary infections and that of aerobic Gram-positive bacteria from postoperative infections were high in the last several years. In this series, we noticed no vancomycin-resistant Gram-positive cocci, but a few strains of moderately arbekacin-resistant MRSA. Carbapenm-resistant P. aeruginosa was seen in less than 10 per cents. Last year we noticed that there were cefazolin-resistant E. coli producing extended spectrum beta-lactamase, but there was no highly cefazolin-resistant E. coli in this year. In the next series, increase of both anaerobic bacteria and Enterococcus spp. should be carefully followed up.

Anti-Bacterial Agents↗
PubMed2004

Ecophysiological interaction between nitrifying bacteria and heterotrophic bacteria in autotrophic nitrifying biofilms as determined by microautoradiography-fluorescence in situ hybridization.

Ecophysiological interactions between the community members (i.e., nitrifiers and heterotrophic bacteria) in a carbon-limited autotrophic nitrifying biofilm fed only NH(4)(+) as an energy source were investigated by using a full-cycle 16S rRNA approach followed by microautoradiography (MAR)-fluorescence in situ hybridization (FISH). Phylogenetic differentiation (identification) of heterotrophic bacteria was performed by 16S rRNA gene sequence analysis, and FISH probes were designed to determine the community structure and the spatial organization (i.e., niche differentiation) in the biofilm. FISH analysis showed that this autotrophic nitrifying biofilm was composed of 50% nitrifying bacteria (ammonia-oxidizing bacteria [AOB] and nitrite-oxidizing bacteria [NOB]) and 50% heterotrophic bacteria, and the distribution was as follows: members of the alpha subclass of the class Proteobacteria (alpha-Proteobacteria), 23%; gamma-Proteobacteria, 13%; green nonsulfur bacteria (GNSB), 9%; Cytophaga-Flavobacterium-Bacteroides (CFB) division, 2%; and unidentified (organisms that could not be hybridized with any probe except EUB338), 3%. These results indicated that a pair of nitrifiers (AOB and NOB) supported a heterotrophic bacterium via production of soluble microbial products (SMP). MAR-FISH revealed that the heterotrophic bacterial community was composed of bacteria that were phylogenetically and metabolically diverse and to some extent metabolically redundant, which ensured the stability of the ecosystem as a biofilm. alpha- and gamma-Proteobacteria dominated the utilization of [(14)C]acetic acid and (14)C-amino acids in this biofilm. Despite their low abundance (ca. 2%) in the biofilm community, members of the CFB cluster accounted for the largest fraction (ca. 64%) of the bacterial community consuming N-acetyl-D-[1-(14)C]glucosamine (NAG). The GNSB accounted for 9% of the (14)C-amino acid-consuming bacteria and 27% of the [(14)C]NAG-consuming bacteria but did not utilize [(14)C]acetic acid. Bacteria classified in the unidentified group accounted for 6% of the total heterotrophic bacteria and could utilize all organic substrates, including NAG. This showed that there was an efficient food web (carbon metabolism) in the autotrophic nitrifying biofilm community, which ensured maximum utilization of SMP produced by nitrifiers and prevented buildup of metabolites or waste materials of nitrifiers to significant levels.

Autoradiography↗
PubMed2004

Percentage of gelatinolytic bacteria among heterotrophic bacteria as indicator of water quality.

The relationship between the physiological group of gelatinolytic bacteria and the abundance of heterotrophic bacteria in freshwater ecosystems was described, based on analysis of 1082 different freshwater samples collected in Croatia. Percentages of gelatinolytic bacteria among the population of heterotrophic bacteria showed a significant negative correlation with the abundance of heterotrophic bacteria. The relation between the physiological group (gelatinolytic bacteria) and heterotrophic bacteria can be considered to be an indicator of the pollution degree of freshwaters. A high relative content of gelatinolytic bacteria (> 76%) always indicates the colony-forming units of heterotrophic bacteria < 1000/mL, which corresponds to the high water quality; gelatinolytic bacteria < 11% indicate polluted waters. Isolated strains of aerobically grown gelatinolytic bacteria were Gram-negative rod-shaped or Gram-positive endospore-forming rod-shaped cells.

Bacteria↗
PubMed1999

Cytokine secretion by stimulated monocytes depends on the growth phase and heat treatment of bacteria: a comparative study between lactic acid bacteria and invasive pathogens.

The consumption of food containing lactic acid bacteria (LAB) has been shown to exert immunomodulatory effects in humans. The specific cellular interaction of these bacteria with immuno-competent cells has not yet been fully understood. Since the TNF-alpha secretion of stimulated monocytes is an important initial response to a bacterial challenge, we investigated the potential of LAB originating from the human intestine or fermented food in comparison to the effect of invasive pathogens. The challenge of monocytes with three LAB strains, Listeria monocytogenes or enterohaemorrhagic Escherichia coli (EHEC) elicited a strain specific, dose-dependent biphasic TNF-alpha secretion. The concentration (EDmax) of bacteria or bacterial cell wall components necessary to induce maximal TNF-alpha secretion (TNFmax) by monocytes was mathematically approximated. It was shown for exponentially growing LAB strains that the maximal TNF-alpha secretion (TNFmax) was stronger (57 to 78%) upon stimulation with living bacteria than with heat killed cells. In contrast to log-phase bacteria, the maximal TNF-alpha secretion of monocytes (TNFmax) was higher (15 to 55%) after the stimulation with heat killed, stationary-phase bacteria when compared to that of live LAB. Thus, monocyte stimulation was clearly affected by the growth phase of bacteria. Purified cell walls of LAB strains revealed only a limited potential for monocyte stimulation. LPS exhibited a higher capacity to stimulate monocytes than purified gram positive cell walls or muramyldipeptide. In comparison to pathogenic bacteria, the maximal secretory TNF-alpha response (TNFmax) was up to 2 fold higher with LAB strains. In general, the amount of bacteria (EDmax) necessary to induce maximal TNF-alpha secretion (TNFmax) was approximately 1 to 3 log higher for heat killed bacteria when compared to live bacterial cells illustrating the significant lower potential of heat killed bacteria to activate monocytes.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

[Occurrence and incidence of bacteria in the area of drinking water with antagonistic relations to indicator bacteria].

During a period of 8 months about 3000 drinking water samples derived from different water works and distribution systems around the area of the city Bonn were examined for colony count, E. coli and coliform bacteria and bacteria suppressing the growth of E. coli and S. faecalis. A modified agar diffusion test was used for the determination of antagonistic substances. Bacteria which revealed an antagonistic activity were isolated and identified. The majority of water samples (81.9% of the samples examined for antagonistic bacteria against E. coli) contained no bacteria in 1 ml and therefore were not examined for antagonistic substances. Only 2.5% of the samples had bacterial counts greater 100 per ml. In 64.2% of the samples examined for bacteria antagonistic to S. faecalis, no counts were found and 2.4% had counts greater 100. The occurrence of fecal indicators was very low in samples with low colony forming units (cfu). At counts greater than 100 we found E. coli within 30.6% and coliform bacteria in 38.8% of the samples examined for bacteria showing antagonistic activity against E. coli. E. coli and coliform bacteria were determined in 24.2% and 33.3% of the samples examined for antagonistic bacteria against S. faecalis. 20% of the samples with colony counts between 1 to 10 contained bacteria showing antagonistic activity against E. coli and at counts greater than 100 they were found in 57.1% of the samples. On the other hand, the quantity of samples with suppression of S. faecalis was 10 to 20% lower and reached a maximum of 39.4% at cfu greater 100. Most of the isolated antagonistic strains belong to the genus Pseudomonas and even 57.8% of the inhibitory strains against E. coli and 26.5% against S. faecalis were found to be P. fluorescens.

Bacteriological Techniques↗
PubMed2006

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2003 and March 2004].

Tendency of isolated bacteria from infections in general surgery during the period from April 2004 to March 2005 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 645 strains including 17 strains of Candida spp. were isolated from 226 (79.0%) of 286 patients with surgical infections. Three hundred and seventeen strains were isolated from primary infections, and 345 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-positive bacteria and anaerobic Gram-negative bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. The isolation rate of aerobic Gram-positive bacteria, such as Enterococcus spp. and Staphylococcus aureus were higher from both types of infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Pseudomonas aeruginosa, Klebsiella pneumoniae and Citrobacter freundii in this order, and from postoperative infections, P. aeruginosa was the most predominantly isolated, followed by E. coli, E. cloacae, and K. pneumoniae. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both primary infections followed by Bilophila wadsworthia. While the isolation rate of B. fragilis group was also the highest from postoperative infections, the following bacteria were Bacteroides thetaiotaomicron and B. wadsworthia in this order. In this series, we noticed no vancomycin-resistant Gram-positive cocci, but a few strains of moderately arbekacin-resistant MRSA. Carbapenem-resistant P. aeruginosa but not multidrug-resistant was seen in 13.3 per cents. Also cefazolin-resistant E. coli probably producing extended spectrum beta-lactamase was seen in 7.0 per cents. We should be carefully followed up the facts that an increasing isolation rates of B. fragilis group and B. wadsworthia which were resistant to both penicillins and cephems.

Anti-Bacterial Agents↗
PubMed2005

Prevalence of etiologic bacteria and beta-lactamase-producing bacteria in acute and chronic maxillary sinusitis at Phramongkutklao Hospital.

BACKGROUND: To date, there is an increasing trend of prescribing antibiotics that cover beta-lactamase-producing bacteria as the first line drug for sinusitis patients in Thailand This practice dose not only increases the treatment cost but might also induce resistance to antimicrobial agents. OBJECTIVE: To determine the prevalence of the pathogenic bacteria in acute and chronic maxillary sinusitis as well as the prevalence of beta-lactamase-producing bacteria. MATERIAL AND METHOD: The maxillary aspiration fluid specimens of 52 acute and chronic sinusitis patients at Phramongkutklao Hospital, Bangkok, Thailand during May 2002-May 2003, were collected. Aerobic and anaerobic cultures were performed and the beta-lactamase activities of isolated bacteria were determined. RESULTS: Of 58 specimens, 44 (75.9%) and 14 (24.1%) specimens were collected from acute and chronic maxillary sinusitis patients, respectively. Of 44 specimens of acute maxillary sinusitis, the predominant isolates were Haemophilus influenzae (13, 29.5%), Streptococcus pneumoniae (4, 9%), Streptococcus viridan (4, 9%), and Klebsiella pneumoniae (4, 9%). 6 (13.6%) of them were beta-lactamase-producing bacteria. Of 14 specimens of chronic maxillary sinusitis, the predominant isolates were Pseudomonas aeruginosa (3, 16.6%), Staphylococcus spp (3, 17.5%) and Streptococcus spp. (2, 11.6%). 1 (7.1%) Haemophilus influenza isolate from this group was beta-lactamase-producing bacteria. The percentage of anaerobe was 8.9%, 23.3% for acute and chronic maxillary sinusitis, respectively. CONCLUSION: The present study was indicated that the common organisms in acute maxillary sinusitis were Haemophilus influenzae and Streptococcus pneumoniae, Streptococcus viridians which were similar to a previous study. But the authors found an increased prevalence of anaerobe bacteria in acute maxillary sinusitis and also found beta-lactamase-producing bacteria, 21.4% Hemophilus influenzae less than the previous studies (which found beta-lactamase-producing bacteria around 50% to 70%). The authors found 23.3% anaerobe bacteria in the chronic maxillary sinusitis, less than the previous studies, and the authors also found 8.9% anaerobe in acute maxillary sinusitis.

Acute Disease↗
PubMed2003

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2001 and March 2002].

Isolated bacteria from infections in general surgery during the period from April 2001 to March 2002 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, four hundred and twenty strains were isolated from 175 (79.2%) of 221 patients with surgical infections. One hundred and eighty-six strains were isolated from primary infections, and 234 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-positive bacteria were predominant, while from postoperative infections, aerobic Gram-positive bacteria were predominant. Among aerobic Gram-positive bacteria, although the isolation rate of Staphylococcus aureus was the highest, followed by that of Enterococcus faecalis from primary infections, the isolation rate of E. faecalis was the highest from postoperative infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa in this order, and from postoperative infections, P. aeruginosa was the most predominantly isolated, followed by Enterobacter spp., E. coli and Klebsiella spp. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. The isolation rate of aerobic Gram-negative bacteria from primary infections and that of aerobic Gram-positive bacteria from postoperative infections were high in the last several years. We noticed no vancomycin-resistant Gram-positive cocci.

Anti-Bacterial Agents↗
PubMed2006

Genomic evidence for antibiotic resistance genes of actinomycetes as origins of antibiotic resistance genes in pathogenic bacteria simply because actinomycetes are more ancestral than pathogenic bacteria.

Although in silico analysis have suggested that the antibiotic resistance genes in actinomycetes appear to be the origins of some antibiotic resistance genes, we have shown that recent horizontal transfer of antibiotic resistance genes from actinomycetes to other medically important bacteria have not taken place. Although it has been speculated in Benveniste and Davies' attractive hypothesis that antibiotic resistance genes of actinomycetes are origins of antibiotic resistance genes in pathogenic bacteria because the actinomycetes require mechanisms such as metabolic enzymes (encoded by the antibiotic resistance genes) to degrade the antibiotics they produce or to transport the antibiotics outside the bacterial cells, this hypothesis has never been proven. Both the phylogenetic tree constructed using 16S rRNA gene sequences and that constructed using concatenated amino acid sequences of 15 housekeeping genes extracted from 90 bacterial genomes showed that the actinomycetes is more ancestral to most other bacteria, including the pathogenic Gram-negative bacteria, Gram-positive bacteria, and Chlamydia species. Furthermore, the tetracycline resistance gene of Bifidobacterium longum is more ancestral to those of other pathogenic bacteria and the actinomycetes, which is in line with the ancestral position of B. longum. These suggest that the evolution of antibiotic resistance genes of antibiotic-producing bacteria in general parallels the evolution of the corresponding bacteria. The ancestral position of the antibiotic resistance genes in actinomycetes is probably unrelated to the fact that they produce antibiotics, but simply because actinomycetes are more ancestral than pathogenic bacteria.

Actinobacteria↗
PubMed2004

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2002 and March 2003].

Tendency of isolated bacteria from infections in general surgery during the period from April 2002 to March 2003 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 334 strains were isolated from 131 (75.3%) of 174 patients with surgical infections. One hundred and seventy-one strains were isolated from primary infections, and 163 strains were isolated from post-operative infections. From primary infections, anaerobic Gram-positive bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. Among aerobic Gram-positive bacteria, although the isolation rate of Staphylococcus aureus was the highest, followed by that of Enterococcus faecalis from primary infections, the isolation rate of E. faecalis was the highest from postoperative infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa in this order, and from postoperative infections, E. coli was the most predominantly isolated, followed by P. aeruginosa, Enterobacter cloacae, and Citobacter freundii. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. The isolation rate of aerobic Gram-negative bacteria from primary infections and that of aerobic Gram-positive bacteria from postoperative infections were high in the last several years. We noticed no vancomycin-resistant Gram-positive cocci nor P. aeruginosa producing metallo-beta-lactamase. But we noticed cefazolin-resistant E. coli probably producing extended spectrum beta-lactamase.

Anti-Bacterial Agents↗
PubMed1987

Urease activity of adherent bacteria and rumen fluid bacteria.

In experiments on six sheep fed on a low nitrogen diet (3.7 g N/day), urease (EC 3.5.1.5) activity (nkat X mg-1 bacterial dry weight) 3 h after feeding was found to be highest in the bacteria adhering to the rumen wall (13.25 +/- 2.10), lower in the rumen fluid bacteria (8.96 +/- 1.35) and lowest in the bacteria adhering to feed particles in the rumen (5.69 +/- 2.13). The urease activity of bacteria adhering to the rumen wall and of the rumen fluid bacteria of six sheep fed on a high nitrogen diet (21 g N/day) was significantly lower than in sheep with a low N intake and in both cases was roughly the same (3.81 +/- 1.37 and 3.76 +/- 1.02 respectively); it was lowest in bacteria adhering to feed particles in the rumen (1.92 +/- 0.90). It is concluded from the results that the urease activity of rumen fluid bacteria and of bacteria adhering to the rumen wall and to feed particles in the rumen is different and that it falls significantly in the presence of a high nitrogen intake. From the relatively high ureolytic activity of bacteria adhering to the rumen wall in the presence of a low nitrogen intake it is assumed that this is one of the partial mechanisms of the hydrolysis of blood urea entering the rumen across the rumen wall and of its reutilization in the rumen-liver nitrogen cycle in ruminants.

Animal Feed↗