
Paul J WeimerUniversity of Wisconsin–Madison | UW · Department of Bacteriology
Paul J Weimer
Ph.D.
About
137
Publications
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Introduction
Anaerobic microbiology, Rumen microbiology, Plant fiber degradation, Microbial production of fuels and chemicals
Additional affiliations
January 1991 - September 2017
Education
October 1975 - August 1978
May 1973 - October 1975
September 1969 - May 1973
Publications
Publications (137)
Characterisation of pomace from citrus fruits, grapes and apples has shown to be rich in compounds that contain untapped energetic value with potential to serve as feedstock for biochemical and biofuel production. This study aimed to investigate the potential of recovering the energy in citrus (CtP), grape (GP) and apple (AP) pomace by extraruminal...
In vitro digestion of pomace with DMSO cryo-rumen fluid is similar to fresh rumen. • Extraruminal fermentations with glycerol cryo-rumen lead to elevated VFA yields. • Fermentation products of DMSO cryo-rumen have distribution similar to fresh rumen. • Unweighted unifrac distance metrics clustered DMSO cryo-rumen with fresh rumen. A R T I C L E I N...
Biomass derived from low-value, high-volume invasive plant species is an attractive, alternative feedstock to produce biofuels and biochemicals. This study aimed to use the carboxylate platform to valorize the invasive leguminous shrub, Prosopis juliflora (Mesquite), by utilizing in vitro rumen fermentations without chemical pretreatment to produce...
Methodology can play a critical rôle in the measurement of digestion kinetics, especially when the objective is to define kinetic parameters for use in formulating rations or modelling animal responses. Measurement of gas production kinetics provides the opportunity to evaluate the rate of digestion of the soluble, more rapidly fermenting fractions...
The rumen is a large bioreactor that enables dairy cattle to derive nutrition from otherwise indigestible plant polymers and compounds. Despite the direct contribution of the rumen's microbial community toward the nutrition of the dairy cow, only a general knowledge has been gained of the metabolic processes within the rumen, and less still is know...
Hemicelluloses are major components of plant biomass, but their fermentation in the rumens of cattle and other ruminants is poorly understood. We compared four species of the ruminally dominant genus Prevotella and the well-known hemicellulose utilizer, Butyrivibrio fibrisolvens, with respect to degradation of several isolated hemicelluloses (xylan...
The microbial community of the rumen is diverse, containing perhaps thousands of individual species. These communities are highly individualized (i.e., vary among animals with respect to relative abundance of individual species) but display functional redundancy that allows conversion of feedstuffs to somewhat similar concentrations and proportions...
Aims:
To assess the effect of two additives on alfalfa silage and on in vitro ruminal fermentation when using ruminal inocula from high feed-efficient (HE) and low feed-efficient (LE) lactating cows.
Methods and results:
First and second cut alfalfa was harvested at 40% bloom stage, treated with control (no additive), Lactobacillus plantarum (LP...
The ruminal microbiome rapidly converts plant biomass to short-chain fatty acids (SCFA) that nourish the ruminant animal host. Because of its high species diversity, functional redundancy, and ease of extraruminal cultivation, this mixed microbial community is a particularly accomplished practitioner of the carboxylate platform for producing fuels...
The fermentation system of mixed ruminal bacteria is capable of generating large amounts of short-chain volatile fatty acids (VFA) via the carboxylate platform in vitro. These VFAs are subject to elongation to larger, more energy-dense products through reverse β-oxidation, and the resulting products are useful as precursors for liquid fuels product...
Full-season corn (Zea mays L.) hybrids take advantage of more of the growing season than shorter-season hybrids oft en leading to greater grain and biomass yield. Many agronomic experiments aimed at corn stover production have been performed at forage harvest rather than later when stover is normally harvested for biofuel measurements. The objectiv...
Fructans are an important nonfiber carbohydrate in cool season grasses. Their fermentation by ruminal microbes is not well described, though such information is needed to understand their nutritional value to ruminants. Our objective was to compare kinetics and product formation of orchardgrass fructan (phlein; PHL) to other nonfiber carbohydrates...
Megasphaera elsdenii is a lactate-utilizing bacterium whose ruminal abundance has been shown to be greatly elevated during milk fat depression (MFD). To further examine this association, a total of 23 cannulated multiparous Holstein cows were examined in 3 experiments in which strains of M. elsdenii were directly dosed into the rumen (∼2 × 10(12) c...
The ruminal microbial community is remarkably diverse, containing 100s of different bacterial and archaeal species, plus many species of fungi and protozoa. Molecular studies have identified a “core microbiome” dominated by phyla Firmicutes and Bacteroidetes, but also containing many other taxa. The rumen provides an ideal laboratory for studies on...
Mixed bacterial communities from the rumen ferment cellulosic biomass primarily to C2–C4 volatile fatty acids, and perform only limited chain extension to produce C5 (valeric) and C6 (caproic) acids. The aim of this study was to increase production of caproate and valerate in short-term in vitro incubations. Co-culture of mixed ruminal microbes wit...
The ruminant animal has evolved to effectively utilize relatively recalcitrant cellulosic biomass to fulfill its needs for growth and reproduction. Although the animal has developed a unique biomass pretreatment process based on mastication and rumination, the key driver of biomass utilization is the microbiota residing in the rumen. The ruminal mi...
Bacteria in the genus Ruminococcus are ubiquitous members of the mammalian gastrointestinal tract. In particular, they are important in ruminants where they digest a wide range of plant cell wall polysaccharides. For example, Ruminococcus albus 7 is a primary cellulose degrader that produces acetate usable by its bovine host. Moreover, it is one of...
Arboreal herbivory is rare among mammals. The few species with this lifestyle possess unique adaptions to overcome size-related constraints on nutritional energetics. Sloths are folivores that spend most of their time resting or eating in the forest canopy. A three-toed sloth will, however, descend its tree weekly to defecate, which is risky, energ...
Sixty samples of 'ForagePlus' oat (Wisconsin Foundation Seeds, Madison, WI) were selected from a previous plot study for analysis of in vitro gas production (IVGP) on the basis of 2 factors: (1) high (n = 29) or low (n = 31) neutral detergent fiber (NDF; 62.7 ± 2.61 and 45.1 ± 3.91%, respectively); and (2) the range of water-soluble carbohydrates (...
M. Lin W. Guo Q. Meng- [...]
D.M. Schaefer
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
M. Lin W. Guo Q. Meng- [...]
D.M. Schaefer
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
M. Lin W. Guo Q. Meng- [...]
D.M. Schaefer
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
M. Lin W. Guo Q. Meng- [...]
D.M. Schaefer
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
M. Lin W. Guo Q. Meng- [...]
D.M. Schaefer
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
"Green juice", obtained by squeezing fresh alfalfa leaves inoculated with lactic acid bacteria, was fermented at room temperature for 7-21d to obtain 12-47glactic acidL(-1). Inoculation of green juice with Streptococcus bovis and incubation at 39°C reduced fermentation time to 8-12h. The resulting "brown juice" from either fermentation had a pH of...
Although clinical benefits of dietary fiber supplementation seem to depend partially on the extent of fiber degradation and fermentation by colonic bacteria, little is known about the effect of supplemental fiber type on bacterial metabolism. In an experiment using a non-adapted human bacterial population from three normal subjects, extent of in vi...
Megasphaera elsdenii T81 grew on either DL-lactate or D-glucose at similar rates (0.85 h(-1)) but displayed major differences in the fermentation of these substrates. Lactate was fermented at up to 210-mM concentration to yield acetic, propionic, butyric, and valeric acids. The bacterium was able to grow at much higher concentrations of D-glucose (...
The purpose of this study was to investigate variability among individual cows in their severity of ruminal acidosis (RA) pre- and postpartum, and determine whether this variability was related to differences in their ruminal bacterial community composition (BCC). Variability in the severity of RA among individual cows was characterized based on ru...
Some silage inoculants help to improve silage quality and promote an increase in milk production, possibly through altering the rumen microflora. We hypothesized that rumen bacterial community composition (BCC) would be different in cows fed alfalfa ensiled with the inoculant Lactobacillus plantarum MTD/1 (LP) compared with those fed alfalfa ensile...
Mixed ruminal microbes were incubated for 24h in vitro with mixed forage and concentrate rations under conditions that differed in starch level (200 or 300g/kg dry matter (DM)), initial pH (6.3 or 6.7) and corn oil (0 or 10g/kg DM), in order to determine effects on fermentation (fiber digestibility, volatile fatty acid (VFA) production) and relativ...
Fibrobacter succinogenes is a cellulolytic bacterium that degrades plant cell wall biomass in ruminant animals and is among the most rapidly fibrolytic of all mesophilic bacteria. The complete genome sequence of Fisuc was completed by the DOE Joint Genome Institute in late 2009. Using new expression tools developed at Lucigen and C5-6 Technologies...
The purpose of this study was to examine the stability and host specificity of a cow's ruminal bacterial community following massive challenge with ruminal microflora from another cow. In each of 2 experiments, 1 pair of cows was selected on the basis of differences in ruminal bacterial community composition (BCC), determined by automated ribosomal...
The performance of two pretreatment methods, sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) and dilute acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production at 180 degrees Celsius for 30 min with a sulfuric acid loading of 5% on oven-dry wood and a 5:1 liquor-to-wood ratio. SPORL was suppleme...
Some perennial grasses, such as reed canarygrass (RCG) and switchgrass (SWG), have prolific yield and low inputs, making them attractive as biomass feedstocks. When harvested as biomass, these grasses are more mature and have much greater yield than when harvested as animal forage. Much is unknown about how harvest equipment performance and storage...
Eighteen ruminally cannulated dairy cattle were fed a series of diets (in 28-d periods) designed to elicit different degrees of milk fat depression (MFD) for the purpose of relating MFD to ruminal bacterial populations. Cows were fed a TMR containing 25% starch (DM basis) supplied as corn silage, a slowly fermented starch (SFS treatment, period 1),...
The influence of pH dynamics on ruminal bacterial community composition was studied in 8 ruminally cannulated Holstein cows fitted with indwelling electrodes that recorded pH at 10-min intervals over a 54-h period. Cows were fed a silage-based total mixed ration supplemented with monensin. Ruminal samples were collected each day just before feeding...
Some perennial grasses, such as reed canarygrass (RCG) and switchgrass (SWG), have prolific yield and low inputs, making them attractive as biomass feedstocks. When harvested as biomass, these grasses are more mature and have much greater yield than when harvested as animal forage. Much is unknown about how harvest equipment performance and storage...
This article unfortunately contained a mistake. The strain designations of two species, Prevotella brevis and Prevotella bryantii, were inadvertently reversed in Table 2. The names and sequences of the corresponding species-specific primers were not in error. The corrected table appears below.
Maize (Zea mays L.) stover has been identified as an important feedstock for the production of cellulosic ethanol. Our objectives were to measure hybrid effect and combining ability patterns of traits related to cellulosic ethanol production, determine if germplasm and mutations used for silage production would also be beneficial for feedstock prod...
Corn stover was harvested with a modified combine that simultaneously harvested grain and stover in separate streams. The harvester was used to collect the following stover fractions using three different heads: cob and husk (ear-snapper head); stalk and leaves (stalk-gathering head); and stalks, leaves, husk, and cob (whole-plant head). Cob and hu...
Abstract The rumen is a highly developed digestive organ in which feed material, particularly plant fiber, is efficiently digested by a complex microbial fermentation. Cellulose, the major component of plant fiber, is digested in the rumen by an assemblage of anaerobic bacteria, fungi, and protozoa. While pure cellulose itself is completely digesti...
The technologies currently in place to convert lignocellulosic biomass to energy are either biochemical or thermochemical, the efficiencies of which may vary depending on the composition of the feedstock. One variable that conversion technologists have wrestled with, particularly in the simultaneous saccharification and fermentation process, is bio...
Effects of sucrose (Suc) concentration on fermentation kinetics and products were evaluated using 3 concentrations of Suc, with 1 concentration of isolated NDF from Bermudagrass fermented together in batch culture in vitro with rumen inoculum. Fixed amounts of medium and inoculum were the protein sources, so protein:Suc decreased with increasing Su...
Plant biomass has attracted interest as a feedstock for biofuels production, but much of this work has been focused on relatively few plant species. In this study, three relatively-unstudied species of warm-season perennial grasses, grown at multiple locations in the eastern and central US and harvested over a three year period, were examined for f...
A grain combine was equipped with a whole-plant corn head and modified to produce single-pass, whole-plant corn harvesting with two crop streams: grain and stover. Capture of potential stover DM varied from 48% to 89% for leaves, from 49% to 92% for stalks, and was greater than 90% for husks and cobs, depending on corn head height. Stover aggregate...
Corn stover has great potential as a biomass feedstock, but harvest and storage of this material is challenged by weather conditions at harvest; material moisture; and equipment shortcomings. Field drying characteristics, harvest efficiency and rate, product bulk density, and storage characteristics were quantified for stover harvested and stored i...
This research investigated the ability of on-farm pretreatments with acid, alkali, ozone or novel enzymes to improve enzymatic degradability of cellulose and hemicelluloses in biomass at the biorefinery. Two perennial grasses, switchgrass (Panicum virgatum) and reed canarygrass (Phalaris arundinacea L.), were direct-cut harvested, pretreated, and s...
Cellulosic biomass, because of its massive availability, represent a feedstock source for production of ethanol and other fuels. Proposed processes based on cellulase enzymes combined with yeast fermentation have received intensive study but are currently not economical due to high enzyme cost and lack of a high-value co-product. An alternative cel...
Seasonal time of switchgrass (Panicum virgatum L.) harvest affects yield and biofuel quality and balancing these two components may vary depending on conversion system. A field study compared fall and spring harvest measuring biomass yield, element concentration, carbohydrate characterization, and total synthetic gas production as indicators of bio...
Real-time polymerase chain reaction (RT-PCR) was used to quantify seven species of lactic acid bacteria (LAB) in alfalfa silage prepared in the presence or absence of four commercial inoculants and in uninoculated corn stover harvested and stored under a variety of field conditions. Species-specific PCR primers were designed based on recA gene sequ...
Current methods for measuring ethanol yields from lignocellulosic biomass are relatively slow and are not well geared for analyzing large numbers of samples generated by feedstock management and breeding research. The objective of this study was to determine if an in vitro ruminal fermentation assay used in forage quality research was predictive of...
Fermentation residues (consisting of incompletely fermented fiber, adherent bacterial cells, and a glycocalyx material that enhanced bacterial adherence) were obtained by growing the anaerobic cellulolytic bacteria Ruminococcus albus 7 or Clostridium thermocellum ATCC 27405 on a fibrous fraction derived from lucerne (Medicago sativa L.). The dried...
The rumen bacterial strains Butyrivibrio fibrisolvens H17c, Fibrobacter succinogenes S85, Lachnospira multiparus 40, Ruminococcus albus 7 and R. flavefaciens FD-1 were compared individually and as a five-species mixture with a rumen inoculum for their ability to degrade lucerne (Medicago sativa L.) stem cell wall polysaccharides. Two maturity stage...
Residues from the fermentation of cellulose by the anaerobic bacteria Ruminococcus albus (strain 7) or Ruminococcus flavefaciens (strains FD-1 or B34b) containing residual cellulose, bacterial cells and their associated adhesins, were examined for their ability to serve as components of adhesives for plywood fabrication. The residues contained diff...
Aims: To determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF), and to identify those that survive best.
Methods and Results: Twelve commercial silage inoculants were added at 107 CFU ml−1 to strained RF (SRF) taken from dairy cows, with and without 5 g l−1 glucose and incubated in vitro at 39°C....
Cysteine is the preferred reducing agent used in the preparation of culture media for the growth of many strictly anaerobic microorganisms; however, redox potential reduction of cysteine is very slow, making it inconvenient if the medium is needed immediately or in large quantity. The time required to reduce culture medium containing resazurin (an...
To determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF), and to identify those that survive best.
Twelve commercial silage inoculants were added at 107 CFU ml-1 to strained RF (SRF) taken from dairy cows, with and without 5 g l-1 glucose and incubated in vitro at 39 degrees C. Changes in pH, LAB...
Treatment of rice straw by the proprietary FIBEX process resulted in increased in vitro digestibility by ruminal microorganisms due to a reduced lag time, increased rate of digestion, increased extent of digestion, and possible removal of inhibitory agents present in untreated rice straw. To determine the value of treated rice straw as a feed ingre...
The direct fermentation of cellulosic biomass to ethanol has long been a desired goal. To this end, we screened the environment for fungal strains capable of this conversion when grown on minimal medium. One strain, identified as a member of the genus Trichoderma and designated strain A10, was isolated from cow dung and initially produced about 0.4...
For the growth of several strictly anaerobic microorganisms, cysteine is the preferred reducing agent because of its low toxicity, but cysteine reduces media only slowly, making it inconvenient if the medium is needed immediately. A culture medium employed to cultivate ruminal anaerobic bacteria supplied with cysteine achieved the desired degree of...
Polydextrose (PD) is a synthetic additive to human foods that has many physical properties of fat, but is poorly metabolized by nonruminant animals. PD was fermented in vitro by mixed ruminal microorganisms, but the kinetics of the fermentation were complex and varied with different ruminal inocula. Gas production during digestion of PD was describ...
In vitro fermentations of pure cellulose by mixed ruminal microorganisms were conducted under conditions in which pH declined within ranges similar to those observed in the rumen. At low cellulose concentrations (12.5 g/L), the first-order rate constants (k) of cellulose disappearance were successively lower at initial pH values of 6.86, 6.56, and...
Competition among three species of ruminal cellulolytic bacteria - Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD-1 and Ruminococcus albus 7 - was studied in the presence or absence of the non-cellulolytic ruminal bacteria Selenomonas ruminantium or Streptococcus bovis. Co-cultures were grown under either batch or continuous conditions...
Growth of the cellulose-synthesizing bacterium Acetobacter xylinum ATCC 53524 in media supplemented with 5% (w/v) glucose and 0.2% (w/v) of a water-soluble, nearly linear xylan from tobacco stalks resulted in the synthesis of a highly crystalline composite having a xylose/glucose ratio ranging from 0.06 to 0.24. The digestion of one composite (88%...