Ecological factors determining establishment of cellulolytic bacteria and protozoa in the rumens of meroxenic lambs

Ecological factors that control the establishment of cellulolytic bacteria and ciliate protozoa in the lamb rumen were studied in meroxenic animals. Axenic lambs received dilutions of rumen liquor from either conventional lambs and sheep (pool A) or meroxenic lambs (pool B). The total number of bacteria established in the rumen was between 10(9) and 5 x 10(10) g-1. In lambs inoculated with dilutions (10(-6), 10(-7), 10(-8)) of pool A, cellulolytic bacteria did not become established. However, subsequent inoculation with Bacteroides succinogenes, resulted in colonization in lambs that had received 10(-6) and 10(-7) dilutions of pool A. However, B. succinogenes became established in only one of three lambs that received the 10(-8) dilution. Similar results were obtained for the protozoan Entodinium sp. With pool B, lambs were inoculated earlier and cellulolytic bacteria were established directly from the 10(-6) and 10(-7) inocula. Polyplastron multivesiculatum establishment occurred readily when inoculated into the lambs which had received the 10(-6) dilution of pool B. Results obtained in this study suggest that establishment of cellulolytic bacteria and protozoa requires an abundant and complex flora and is favoured by early animal inoculation.     

浅谈几种微生物价值开发再利用

微生物从发现、发展到现在已经有多年历史,其利用价值的开发也不断的被广大科研人员所研究,从最初的单一发酵食品到现在广泛应用于食品、医药卫生、植物疾病防治、畜禽养殖废弃物处理等均表现出微生物在人类、动植物乃至所有生物及非生物方面均有不可比喻的利用价值.本研究以霉菌和酵母菌两个菌属的不同菌种为例对其作用、发展前景及相关内容进行阐述,并对微生物系列中的微生态制剂进行探讨,表明微生物是一种潜在的可利用资源,其在未来的世界发展中占有重要位置.     

Influence of climatic factors on the development of pneumonia in lambs

Pneumonia is responsible for important economical losses in the sheep industry in Spain and many other sheep-rearing countries, being the main cause of lamb death, and of losses due to condemnations in abattoirs and of drug costs. This respiratory syndrome is a complex disease involving the relationship between host and environment. The present study analyses the influence of environmental factors on the development of pneumonia in lambs. Statistically significant correlations were found between pneumonia as a cause of lamb death and climatic factors such as rainfall, humidity and intensity and direction of wind. The type of farm building was also an important factor to take into account in order to improve the prevention of pneumonia in lambs. Moreover, the age of the lambs was seen to be a significant item in the study of pneumonia. Respiratory pathology increased from 23 days of age. This fact permits the implementation of measures from birth to 23 days with a view to reducing pneumonia and its negative influence on lamb production. The paper discusses the practical implications of these findings for sheep production.     

Influence of climatic factors on the development of pneumonia in lambs

Pneumonia is responsible for important economical losses in the sheep industry in Spain and many other sheep-rearing countries, being the main cause of lamb death, and of losses due to condemnations in abattoirs and of drug costs. This respiratory syndrome is a complex disease involving the relationship between host and environment. The present study analyses the influence of environmental factors on the development of pneumonia in lambs. Statistically significant correlations were found between pneumonia as a cause of lamb death and climatic factors such as rainfall, humidity and intensity and direction of wind. The type of farm building was also an important factor to take into account in order to improve the prevention of pneumonia in lambs. Moreover, the age of the lambs was seen to be a significant item in the study of pneumonia. Respiratory pathology increased from 23 days of age. This fact permits the implementation of measures from birth to 23 days with a view to reducing pneumonia and its negative influence on lamb production. The paper discusses the practical implications of these findings for sheep production.     

Carcass traits and meat fatty acid composition of Barbarine lambs reared on rangelands or indoors on hay and concentrate

The objective of this study was to compare carcass and meat quality between Barbarine lambs raised on rangelands and those reared indoors. A total of 24 weaned male lambs (23.2 kg) were allotted into two groups. The first group (GS) grazed pasture dominated by natural shrubs and was supplemented with 100 g of concentrate. The second group (HS) received oat hay and 200 to 300 g supplement of the same concentrate in order to obtain the same average daily gain (ADG) as the GS group. Six lambs from each group were slaughtered. Lambs to be slaughtered were randomly identified at the beginning of the trial. Carcass traits (offals percentage, dressing percentage, cuts yield, tissue composition, fatness and conformation) were determined; pH and meat and fat color were measured. Samples from longissimus lumborum were collected to analyze fatty acid composition. The GS group was characterized by a higher offals percentage, associated with higher lungs, heart, liver and kidney percentage. Carcass dressing percentage defined as the rate between hot carcass weight and empty BW was lower by 3.4% in the GS group. No differences were observed for carcass meat yield and carcass and leg compactness. Shoulder bone percentage of the GS group was higher, without differences in fat and lean percentages. Fat thickness, kidney and tail fats were lower in the GS lambs. However, intramuscular fat content was not affected. Percentages of saturated fatty acids and polyunsaturated fatty acids (PUFA) were not modified, whereas levels of n-3 and long n-3PUFA (EPA, DPA and DHA) as well as Δ⁵ desaturase plus Δ⁶ desaturase index were higher for the GS group. Thrombogenic and atherogenic indexes were not altered. No significant effects were observed for meat pH, meat and fat color. Despite having the same ADG, lambs from the GS group were less fatty, and their meat was richer in beneficial fatty acids.     

Effects of methanogenic inhibitors on methane production and abundances of methanogens and cellulolytic bacteria in in vitro ruminal cultures

The objective of this study was to systematically evaluate and compare the effects of select antimethanogen compounds on methane production, feed digestion and fermentation, and populations of ruminal bacteria and methanogens using in vitro cultures. Seven compounds, including 2-bromoethanesulphonate (BES), propynoic acid (PA), nitroethane (NE), ethyl trans-2-butenoate (ETB), 2-nitroethanol (2NEOH), sodium nitrate (SN), and ethyl-2-butynote (EB), were tested at a final concentration of 12 mM. Ground alfalfa hay was included as the only substrate to simulate daily forage intake. Compared to no-inhibitor controls, PA, 2NEOH, and SN greatly reduced the production of methane (70 to 99%), volatile fatty acids (VFAs; 46 to 66%), acetate (30 to 60%), and propionate (79 to 82%), with 2NEOH reducing the most. EB reduced methane production by 23% without a significant effect on total VFAs, acetate, or propionate. BES significantly reduced the propionate concentration but not the production of methane, total VFAs, or acetate. ETB or NE had no significant effect on any of the above-mentioned measurements. Specific quantitative-PCR (qPCR) assays showed that none of the inhibitors significantly affected total bacterial populations but that they did reduce the Fibrobacter succinogenes population. SN reduced the Ruminococcus albus population, while PA and 2NEOH increased the populations of both R. albus and Ruminococcus flavefaciens. Archaeon-specific PCR-denaturing gradient gel electrophoresis (DGGE) showed that all the inhibitors affected the methanogen population structure, while archaeon-specific qPCR revealed a significant decrease in methanogen population in all treatments. These results showed that EB, ETB, NE, and BES can effectively reduce the total population of methanogens but that they reduce methane production to a lesser extent. The results may guide future in vivo studies to develop effective mitigation of methane emission from ruminants.     

Influence of vanillin on the production of cellulolytic and xylanolytic enzymes from a wood-rotting fungus,Coriolus versicolor

To examine the influence of a phenolic compound on the production of cellulolytic and xylanolytic enzymes of a woodrotting fungusCoriolus versicolor, a two-dimensional map of enzyme activity was constructed with various concentrations of cellobiose and vanillin. The productions of CMCase, xylanase, β-glucosidase, and β-xylosidase increased with higher cellobiose concentration and were markedly enhanced by addition of vanillin. Higher ratio of vanillin/cellobiose activated the production of these enzymes. Only acetyl esterase, which is not actively produced at the ligninolytic stage ofC. versicolor, was inhibited by the monolignol vanillin. As the presence of vanillin is considered to approximate conditions of wood decay more closely than its absence, the present result demonstrates that addition of vanillin, a phenolic compound, enhanced the production of cellulolytic and xylanolytic enzymes for wood cell wall degradation.     

Influence of various nitrogen and carbon sources on the production of pectolytic,cellulolytic and proteolytic enzymes byAspergillus niger

Three isolates ofAspergillus niger produced polygalacturonase (PG) and pectin methyl galacturonase (PMG) in the presence of organic and inorganic nitrogen sources. Complete inhibition of PG PMG cellulase (C_x) and proteinase synthesis was found in the presence of cystine in all isolates. Maximum biomass was found in sodium nitrate whereas no isolate could grow in the presence of cystine. A correlation between biomass and enzyme production could be obtained when sodium nitrate and cystine were added to the medium separately. All isolates produced pectic cellulolytic and proteolytic enzymes in the presence of various native carbon sources. Sodium polypectate was found to be the best carbon source for the production of PG and PMG; pectin inhibited completely the production of PG and PMG. Maximum cellulase production was brought about by cotton in all three isolates. Maximum proteinase production was observed with gelatin which served as poor substrate for fungal growth. Sucrose supported maximum fungal growth in comparison with all other native carbon sources. The increased production of pectolytic cellulolytic and proteolytic enzymes in the presence of sodium polypectate reflected a stimulation rather than an induction of synthesis of these enzymes.     

The use of stoned olive cake and rolled linseed in the diet of intensively reared lambs: effect on the intramuscular fatty-acid composition

The aim of the present study was to evaluate the effect of the inclusion of stoned olive cake and rolled linseed in a concentrate-based diet for lambs on the fatty-acid composition of polar and non-polar intramuscular lipids of the longissimus dorsi muscle. To achieve this objective, 32 Appenninica lambs were randomly distributed into four groups of eight lambs each and were fed conventional cereal-based concentrates (diet C); concentrates containing 20% on a dry matter (DM) basis of rolled linseed (diet L); concentrates containing 35% DM of stoned olive cake (diet OC); and concentrates containing both rolled linseed (10% DM) and stoned olive cake (17% DM; diet OCL). The concentrates were administered together with grass hay at a 20:80 forage:concentrate ratio. Growing performances and carcass traits were evaluated. The fatty-acid composition was analysed in the total intramuscular lipids, as well as in the polar and neutral lipids. The average feed intake and the growth performance of lambs were not affected by the dietary treatments, as a consequence of similar nutritional characteristics of the diets. The inclusion of rolled linseed in the L and OCL diets increased the content of C18:3 n-3 in intramuscular total lipids, which was threefold higher in meat from the L lambs and more than twofold higher in meat from the OCL lambs compared with the C and OC treatments. The n-6:n-3 ratio significantly decreased in the meat from lambs in the L and OCL groups, reaching values below 3. The L treatment resulted in the highest level of trans-18:1 fatty acids in the muscle. Regardless of the dietary treatment, the t10-18:1 was the major isomer, representing 55%, 45%, 49% and 45% of total trans-18:1 for C, L, OC and OCL treatments, respectively. Neutral lipids from the OC-fed lambs contained the highest amount of c9-18:1 (more than 36% of total fatty acids); however, the content of c9-18:1 did not differ between the OC and C lambs, suggesting an intensive biohydrogenation of dietary c9-18:1 in the case of OC treatment. The highest content of c9,t11-18:2 was detected in the intramuscular fat from the L-fed lambs, followed by the OCL treatment. A similar trend was observed in the neutral lipid fraction and, to a lower extent, in the polar lipids.     

Influence of pH on methane and sulfide production from methanol

To investigate the influence of pH on methane and sulfide production, continuous cultures were done using a bio-reactor packed with pumice stone. Sulfate (1 g SO₄²⁻·l⁻¹) in a methanol defined medium (10 g·l⁻¹) was almost completely reduced to sulfide at pHs between 7.0 and 7.5 in methane fermentation, but at pHs between 6.2 and 6.8, sulfate reduction to sulfide was suppressed up to 40%. In addition, methane fermentation was not inhibited by 10 g sulfate·l⁻¹.     

Formate and glucose stimulation of methane and hydrogen production in rumen liquor

Membrane-inlet mass spectrometry was used to investigate the effects of increasing the concentration of the rumen metabolites, formate and glucose, upon CH₄ and H₂ production during fermentation by unfractionated rumen liquor. Additions of formate up to 3.6 mM stimulated CH₄ and then excess H₂ production. Each addition caused a large accumulation of H₂ (>40 µM), which returned to in situ concentrations after periods of more than 1 h. Glucose additions up to 2.0 mM gave linear increases in CH₄ and H₂ production. The conversion of substrate carbon into CH₄ was found to decrease from 34% to 9% for formate, as concentrations were increased (1.6–3.6 mM); approximately 13.5% of the glucose carbon was converted to CH₄.     

Influence of plants on redox potential and methane production in water-saturated soil

Three chironomid midge (Diptera: Chironomidae) species (Cricotopus sylvestris (Fabricius); Psectrocladius limbatellus (Holmgren), Tanytarsus fimbriatus Reiss and Fittkau) live at high densities and dominate the midge assemblage found in slow sand filter beds. After filter beds are drained and cleaned, the substratum consists of sand of different particle sizes, but once beds are refilled and in operation, organic material accumulates on the sand and Cladophora grows. In laboratory experiments, we found that larvae of the three midge species preferred different substratum types: C. sylvestris preferred sand to both Cladophora and organic material, P. limbatellus preferred Cladophora, and Tanytarsus sp. preferred organic material. Some evidence of preference for one particle size was also found, but compared with substratum types, this was neither as marked or contrasting between the three species. The contrasting preferences that we found in the laboratory suggest that the substratum will influence the microdistribution of the three species in filter beds, and provide further evidence of the importance of substratum in midge assemblages.     

Effect of nickel on methane production and butyric acid utilization in a downflow fixed-film reactor

Summary Butyric acid conversion by a mixed methanogenic population in a pilot scale anaerobic downflow fixed-film reactor (DFFR), treating a cheese factory effluent was increased by the addition of nickel (30 mg/l NiCl₂. 6H₂O). The butyric acid concentration dropped abruptly (2300 to 150 mg/l) when the reactor was fed with Ni (II). Furthermore, when running two lab. scale DFFRs butyric acid utilization and methane production were slightly higher within the reactor supplemented with nickel than in the control reactor (without nickel).     

Influence of Ni, Co, Fe, and Na additions on methane production in Sphagnum-dominated Northern American peatlands

Although Sphagnum (moss)-dominated, northern peatlandecosystems harbor methane (CH₄)-producing microorganisms(methanogens) and are a significant source of atmosphericCH₄, rates of CH₄ production vary widely amongdifferent systems. Very little work has been done to examine whetherconcentrations of cations and metal elements may account for thevariability. We examined rates of CH₄ production in peat fromfive geographically and functionally disparateSphagnum-dominated peatlands by incubating peat samples invitro with and without additions of trace metals (Fe, Ni, Co) andbase cations (Ca, Li, Na). In peat from the most mineral poor sites, theaddition of metals and Na enhanced CH₄ production beyond thatobserved in controls. The same treatments in mineral rich sites yieldedno effect or an inhibition of CH₄ production. None of thetreatments affected anaerobic respiration, measured as CO₂production, in the in vitro incubations of peat, except addedcitrate, suggesting that methanogens, and not the entire anaerobiccommunity, can be limited by the availability of metal elements andcations.     

Colonization, persistence, and tissue tropism of Escherichia coli O26 in conventionally reared weaned lambs

Escherichia coli O26 is recognized as an emerging pathogen associated with disease in both ruminants and humans. Compared to those of E. coli O157:H7, the shedding pattern and location of E. coli O26 in the gastrointestinal tract (GIT) of ruminants are poorly understood. In the studies reported here, an stx-negative E. coli O26 strain of ovine origin was inoculated orally into 6-week-old lambs and the shedding pattern of the O26 strain was monitored by serial bacteriological examination of feces. The location of colonization in the GIT was examined at necropsy at two time points. The numbers of O26 organisms excreted in feces declined from approximately 10(7) to 10(4) CFU per gram of feces by day 7 and continued at this level for a further 3 weeks. Beyond day 30, excretion was from few animals, intermittent, and just above the detection limit. By day 38, all fecal samples were negative, but at necropsy, O26 organisms were recovered from the upper GIT, specifically the ileum. However, no attaching-effacing (AE) lesions were observed. To identify the location of E. coli O26 within the GIT early after inoculation, two lambs were examined postmortem, 4 days postinoculation. High numbers of O26 organisms were recovered from all GIT sites examined, and approximately 10(9) CFU were recovered from 1 gram of ileal tissue from one animal. Despite high numbers of O26 organisms, AE lesions were identified on the mucosa of the ascending colon of only one animal. These data indicate that E. coli O26 readily colonizes 6-week-old lambs, but the sparseness of AE lesions suggests that O26 is well adapted to this host, and mechanisms other than those dependent upon intimin may play a role in persistence.     

Establishment of cellulolytic bacteria and development of fermentative activities in the rumen of gnotobiotically-reared lambs receiving the microbial additive Saccharomyces cerevisiae CNCM I-1077

We studied the effects of a yeast additive used in ruminant nutrition on the establishment of cellulolytic bacteria, on plant cell wall degradation and on digestive functions in the rumen of gnotobiotically-reared lambs. Cellulolytic bacteria inoculated to the lambs tended to become established earlier in the presence of Saccharomyces cerevisiae CNCM I-1077 (SC). In addition, their population was maintained at a higher level, when the physico-chemical conditions of the biotope were altered. In these lambs, specific activities of fibrolytic enzymes were greater, and in sacco degradation of wheat straw tended to increase. In the presence of SC there was a decrease in ruminal ammonia concentration and a higher volatile fatty acid (VFA) concentration when lambs were 20 to 50 days old. These data suggest that this yeast strain may stimulate the development of cellulolytic microflora and enhance microbial activity in the rumen of young ruminants. Such activity could be beneficial in preventing microbial imbalance and a reduction of rumen function efficiency in the case of nutritional transitions. Further studies with conventional animals will soon be performed in order to verify these dings.     

Effect of organic zinc supplementation on growth, nutrient utilization and mineral profile in lambs

To study the efficacy of organic zinc (Zn) supplementation on growth, nutrient utilization and mineral profile as compared to inorganic source [zinc sulphate (ZnSO₄)], 18 Muzaffarnagari male lambs of 11.30 ± 0.45 kg mean body weight (4–5 months of age) were divided into three groups of six animals in each in a randomized block design. Lambs in the control group were fed a standard total mixed ration (TMR) consisted of 60 kg/100 kg of concentrate mixture (CM) and 40 kg/100 kg of wheat straw. CM was consisted of 300 g/kg crushed maize grain, 270 g/kg soybean meal, 400 g/kg wheat bran, 20 g/kg mineral mixture (without Zn) and 10 g/kg common salt. Animals in the experimental groups were additionally supplemented with 20 mg Zn/kg of diet either through inorganic (ZnSO₄) or organic [Zn-methionine AA complex (Zn-meth)] sources. Experimental feeding was done for a period of 150 days including a 6 days metabolism trial. The intake of dry matter (DM), organic matter (OM), crude protein (CP), digestible CP and total digestible nutrients and digestibility of DM, OM, CP, ether extract, neutral detergent fibre and hemicellulose were comparable (P>0.05) among the three groups. However, digestibility of cellulose and acid detergent fibre was significantly (P<0.05) higher in Zn-meth group as compared to control group. Though the balance of calcium was adversely affected (P<0.01) in both the Zn supplemented groups, but it was significantly higher in Zn-meth group compared to ZnSO₄ group. While apparent absorption and retention of nitrogen, phosphorus, copper, iron and manganese were similar (P>0.05) among different groups, retention of Zn (P<0.05) as well as its concentration in the serum (P<0.01) were highest in Zn-meth group, followed by ZnSO₄ group and lowest in the control group, suggesting higher bioavailability of Zn from Zn-meth as compared to ZnSO₄. Average daily gain of the lambs and feed conversion efficiency were also significantly (P<0.05) higher in Zn-meth group as compared to control and ZnSO₄ groups, suggesting a positive role of organic zinc supplementation on the performance of lambs.     

Effect of hydrogen peroxide production and the Fenton reaction on membrane composition of Streptococcus pneumoniae

As part of its aerobic metabolism, Streptococcus pneumoniae generates high levels of H(2)O(2) by pyruvate oxidase (SpxB), which can be further reduced to yield the damaging hydroxyl radicals via the Fenton reaction. A universal conserved adaptation response observed among bacteria is the adjustment of the membrane fatty acids to various growth conditions. The aim of the present study was to reveal the effect of endogenous reactive oxygen species (ROS) formation on membrane composition of S. pneumoniae. Blocking carbon aerobic metabolism, by growing the bacteria at anaerobic conditions or by the truncation of the spxB gene, resulted in a significant enhancement in fatty acid unsaturation, mainly cis-vaccenic acid. Moreover, reducing the level of OH(.) by growing the bacteria at acidic pH, or in the presence of an OH(.) scavenger (salicylate), resulted in increased fatty acid unsaturation, similar to that obtained under anaerobic conditions. RT-PCR results demonstrated that this change does not originate from a change in mRNA expression level of the fatty acid synthase II genes. We suggest that endogenous ROS play an important regulatory role in membrane adaptation, allowing the survival of this anaerobic organism at aerobic environments of the host.