Tuning the functional properties of lignocellulosic films by controlling the molecular and supramolecular structure of lignin.

This study investigated the relationships between lignin molecular and supramolecular structures and their functional properties within cellulose-based solid matrix, used as a model biodegradable polymer carrier. Two types of derivatives corresponding to distinct structuration levels were prepared from a single technical lignin sample (PB1000): phenol-enriched oligomer fractions and colloidal nanoparticles (CLP). The raw lignin and its derivatives were formulated with cellulose nanocrystals or nanofibrils to prepare films by chemical oxidation or pressure-assisted filtration. The films were tested for their water and lignin retention capacities, radical scavenging capacity (RSC) and antimicrobial properties. A structural investigation was performed by infrared, electron paramagnetic resonance spectroscopy and microscopy. The composite morphology and performance were controlled by both the composition and structuration level of lignin. Phenol-enriched oligomers were the compounds most likely to interact with cellulose, leading to the smoothest film surface. Their RSC in film was 4- to 6-fold higher than that of the other samples. The organization in CLP led to the lowest RSC but showed capacity to trap and stabilize phenoxy radicals. All films were effective against S. aureus (gram negative) whatever the lignin structure. The results show the possibility to tune the performances of these composites by exploiting lignin multi-scale structure.

Analysis of Xanthomonas oryzae pv. oryzicola population in Mali and Burkina Faso reveals a high level of genetic and pathogenic diversity.

Bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola was first reported in Africa in the 1980s. Recently, a substantial reemergence of this disease was observed in West Africa. Samples were collected at various sites in five and three different rice-growing regions of Burkina Faso and Mali, respectively. Sixty-seven X. oryzae pv. oryzicola strains were isolated from cultivated and wild rice varieties and from weeds showing BLS symptoms. X. oryzae pv. oryzicola strains were evaluated for virulence on rice and showed high variation in lesion length on a susceptible cultivar. X. oryzae pv. oryzicola strains were further characterized by multilocus sequence analysis (MLSA) using six housekeeping genes. Inferred dendrograms clearly indicated different groups among X. oryzae pv. oryzicola strains. Restriction fragment length polymorphism analysis using the transcriptional activator like effector avrXa7 as probe resulted in the identification of 18 haplotypes. Polymerase chain reaction-based analyses of two conserved type III effector (T3E) genes (xopAJ and xopW) differentiated the strains into distinct groups, with xopAJ not detected in most African X. oryzae pv. oryzicola strains. XopAJ functionality was confirmed by leaf infiltration on 'Kitaake' rice Rxo1 lines. Sequence analysis of xopW revealed four groups among X. oryzae pv. oryzicola strains. Distribution of 43 T3E genes shows variation in a subset of X. oryzae pv. oryzicola strains. Together, our results show that African X. oryzae pv. oryzicola strains are diverse and rapidly evolving, with a group endemic to Africa and another one that may have evolved from an Asian strain.

Phenotypic and genetic diversity of rice seed-associated bacteria and their role in pathogenicity and biological control.

AIMS: To study the phenotypic and genetic diversity of culturable bacteria associated with rice seed and to asses the antagonistic and pathogenic potential of the isolated bacteria. METHODS AND RESULTS: Seed of rice cultivar PSBRc14 was collected from farmers' fields of irrigated lowland in southern Luzon, Philippines. Isolations of distinct colonies yielded 498 isolates. Classification of the isolates according to similarities in cellular characteristics, whole-cell fatty acid composition, and colony appearance differentiated 101 morphotype groups. Predominant bacteria were Coryneform spp., Pantoea spp. and Pseudomonas spp. Other bacteria regularly present were Actinomycetes spp., Bacillus pumilus, B. subtilis, Burkholderia glumae, Enterobacter cloacae, Paenibacillus polymyxa, Staphylococcus spp. and Xanthomonas spp. The genetic diversity among isolates was assessed by BOX-PCR fingerprinting of genomic DNA and represented 284 fingerprint types (FPTs). Most FPTs (78%) were not shared among samples, while eight FPTs occurred frequently in the samples. Seven of these FPTs also occurred frequently in a previous collection made from rainfed lowlands of Iloilo island, Philippines. Sixteen per cent of the isolates inhibited in vitro the mycelial growth of the rice pathogens Rhizoctonia solani and Pyricularia grisea, whereas 4% were pathogens identified as Burkholderia glumae, Burkholderia gladioli and Acidovorax avenae ssp. avenae. CONCLUSIONS: This study reveals a broad morphological and genetic diversity of bacteria present on seed of a single rice cultivar. SIGNIFICANCE AND IMPACT OF THE STUDY: This line of work contributes to a better understanding of the microbial diversity present on rice seed and stresses its importance as a carrier of antagonists and pathogens.

Pseudomonads associated with midrib rot and soft rot of butterhead lettuce and endive.

During the past ten years, bacterial soft rot and midrib rot of glasshouse-grown butterhead lettuce (Lactuca sativa L. var. capitata) and field-grown endive (Cichorium endivia L.) has become increasingly common in the region of Flanders, Belgium. Severe losses and reduced market quality caused by bacterial rot represent an important economical threat for the production sector. Symptoms of midrib rot are a brownish rot along the midrib of one or more inner leaves, often accompanied by soft rot of the leaf blade. Twenty-five symptomatic lettuce and endive samples were collected from commercial growers at different locations in Flanders. Isolations of dominant bacterial colony types on dilution plates from macerated diseased tissue extracts yielded 282 isolates. All isolates were characterized by colony morphology and fluorescence on pseudomonas agar F medium, oxidase reaction, and soft rot ability on detached chicory leaves. Whole-cell fatty acid methyl esters profile analyses identified the majority of isolates (85%) as belonging to the Gammaproteobacteria, which included members of the family Enterobacteriaceae (14%) and of the genera Pseudomonas (73%), Stenotrophomonas (9%), and Acinetobacter (3%). Predominant bacteria were a diverse group of fluorescent Pseudomonas species. They were further differentiated based on the non-host hypersensitive reaction on tobacco and the ability to rot potato slices into 4 phenotypic groups: HR-/P- (57 isolates), HR-/P+ (54 isolates), HR+/P (16 isolates) and HR+/P+ (35 isolates). Artificial inoculation of suspensions of HR-, pectolytic fluorescent pseudomonads in the leaf midrib of lettuce plants produced various symptoms of soft rot, but they did not readily cause symptoms upon spray inoculation. Fluorescent pseudomonads with phenotype HR+ were consistently isolated from typical dark midrib rot symptoms, and selected isolates reproduced the typical midrib rot symptoms when spray-inoculated onto healthy lettuce plants.

Bacterial populations associated with rice seed in the tropical environment.

ABSTRACT During the 1995 wet season, harvested rice seed was collected from farmers' fields at different locations in Iloilo, Philippines. Bacterial isolations from crushed seed yielded 428 isolates. The isolates were characterized by BOX-polymerase chain reaction fingerprinting of total genomic DNA and represented 151 fingerprint types (FPT). Most FPTs were found on a single occasion, although matching fingerprints for isolates from different samples also were found. Identifications were made by cellular fatty acid methyl ester analysis and additional use of Biolog GN/GP MicroPlates and API 20E/50CHE systems. The predominant bacteria were Enterobacteriaceae (25%), Bacillus spp. (22%), and Pseu-domonas spp. (14%). Other bacteria regularly present were identified as Xanthomonas spp., Cellulomonas flavigena, and Clavibacter michiganense. Of the total number of isolated bacteria, 4% exhibited in vitro antifungal activity against Rhizoctonia solani or Pyricularia grisea. Two percent of isolates were pathogens identified as Burkholderia glumae and Burkholderia gladioli. Five percent of isolates induced sheath necrosis on only 50 to 90% of inoculated plants and were related to Bacillus pumilus, Paenibacillus spp., Pseudomonas spp., and Pantoea spp.

Effect of yeast supplementation on health, performance and rumen fermentation in beef bulls.

The effect of 0, 6 or 60 g yeast (Saccharomyces cerevisiae) daily on health and performance was investigated in 90 double-muscled and 48 non-double-muscled Belgian White-blue bulls during 60 and 51 days, respectively, upon arrival at the experimental farm. The yeast was incorporated in the concentrate, which was fed at 2 kg d-1 during the first ten days and at 2.5 kg d-1 afterwards. Besides, maize silage was fed up to 8 kg d-1, while grass hay was offered ad libitum. Feed intake, growth rate and number of sick animals were not affected by the yeast addition. Morbid animals required a similar number of days with antibiotic therapy for each yeast level within each beef strain. Rumen samples taken from 6 non-double-muscled bulls in the last but one week showed a decreased concentration of volatile fatty acids when 6 g yeast was fed daily. Except butyric acid concentration, rumen fermentation parameters were not altered. Yeast supplementation during an adaptation period after purchase did not affect health status and growth performance.

Beet fed as such or ensiled with maize and fresh potatoes in diets for finishing bulls.

The use of beet for beef production after ensiling together with maize was studied in two experiments involving 112 and 114 White-blue bulls. In the first experiment maize silage (I) was compared with mixed silage of maize and fodder beet (II) or sugar beet (III) (ratio: 2/1, DM-basis). In the second experiment maize silage (I) was compared with mixed silage of 0.67 maize and 0.33 sugar beet (II) or maize silage and fresh sugar beet (ratio: 2/1, DM basis) (III) or fresh sugar beet and potatoes afterwards at 4% of the live weight and maize silage (IV). From day 113 onwards, mixed silage was also fed to group III and sugar beet were replaced by raw potatoes in group IV. The basic diet was always supplemented with concentrate at 0.75% of the live weight. In experiment 1 live weight gain was slightly but not significantly higher for the mixed silages, although daily net energy intake per kg metabolic weight was higher. Feed efficiency was not significantly different among groups. Mixed silages yielded more fat in the carcass. In the second experiment initial growth rates were not significantly affected by the use of sugar beet or mixed silages. Afterwards, they were increased in comparison with maize silage. Also in this experiment, daily net energy intake was increased by sugar beet, or by potatoes. Energy efficiency did not differ among groups. This experiment did not show significant differences for the carcass composition. However, EUROP fatness score was higher for diets containing one third sugar beet. Most meat quality parameters were not affected by the diets. Only the lightness was different between III and IV.

Effect of a viable yeast culture on digestibility and rumen fermentation in sheep fed different types of diets.

Five mature wethers fitted with rumen fistulas were fed grass hay and a sugarbeet-pulp-based concentrate or maize silage and a cereal-based concentrate (50/50 digestible organic matter basis), or without with 5 g yeast supplement (Saccharomyces cerevisiae, Biosaf) per day in a latin square design. Diets were given for a 28-d adaptation period, followed by a 10-d collection period to determine digestibility and nitrogen retention data. Afterwards, rumen samples were taken on 3 consecutive days and analysed for volatile fatty acids, pH and ammonia. Digestibility and nitrogen balance were not affected by yeast treatment. Supplementation of yeast increased acetate: propionate ratio, butyrate, isoacids, pH and ammonia. The effects were more pronounced for the maize silage diet. These results demonstrate that the effect of yeast culture on rumen fermentation may depend on the nature of the diet. Living yeast cell number in the rumen fluid rapidly declined when dietary yeast was ceased. Furthermore, yeast cells survived the passage through the digestive tract.

Effect of duration of a beta-agonist treatment on growth, feed intake and carcass characteristics in finishing bulls.

Two experiments were conducted to study the effect of a different duration of dietary cimaterol on animal performances and carcass characteristics in finishing Belgian White-blue bulls. They received a concentrate diet ad libitum during 228 days on average, containing no cimaterol (control) or 4 ppm cimaterol during 71, 127 or 246 days (experiment 1) or during the last 76, 108 or 136 days before the end of the fattening period (experiment 2). Prior to slaughter a 6-day withdrawal period was applied. There was a significant increase in the growth rate immediately after the onset of the cimaterol feeding. A long-term cimaterol administration of 4.5 to 8 months tended to decrease daily gain towards the end of the experiment. Average daily feed intake was only slightly reduced when cimaterol was fed from the beginning of the experiment. Feed conversion was improved by cimaterol, but the effect was smaller after a long-term administration. Increased Longissimus dorsi area and hindleg width revealed muscle hypertrophy in cimaterol-treated bulls. Dressing percent and carcass meat content were increased. Optimum duration of 4 ppm dietary cimaterol varied between 2.5 and 4 months.

Transient occurrence of extrachromosomal DNA of an Arabidopsis thaliana transposon-like element, Tat1.

Analysis of 11 genomic clones containing the S-adenosylmethionine synthetase 1 gene (sam1) of Arabidopsis thaliana revealed the presence of a 431-base-pair (bp) insertion in the 3' end of sam1 in one of these clones. The inserted sequence, called Tat1, shows structural features of a transposon. It is flanked by a 5-bp duplication of the target site DNA and has 13-bp inverted repeats at its termini. Two highly homologous elements situated in a different genomic context were isolated from a genomic library. Genomic Southern analysis indicates that there are at least four copies of Tat1 present in the A. thaliana ecotype Columbia genome. Different hybridization patterns are observed with DNAs derived from different ecotypes of Arabidopsis thaliana, indicating that the element has moved since the divergence of these ecotypes. In two populations of A. thaliana, linear extrachromosomal Tat1-homologous DNA has been observed. The presented data are consistent with the hypothesis that Tat1 is an active transposable element.

The estimation of nutritive value of dairy cattle feed.

A survey is given of different methods used for the estimation of the net energy lactation and the digestible crude protein content of forages (grass hay, grass silage, maize silage) as well as tuber crops (fodder beet, turnips, raw potatoes), by-products (dried sugarbeet pulp, pressed sugarbeet pulp), compound feeds and raw ingredients for dairy cattle. The following methods are discussed: --methods only based on chemical parameters: crude fibre and cell walls. --methods using rumen fluid from fistulated animals: the two step in vitro digestibility technique, the Hohenheim Futterwert test. --methods using enzyme (cellulase) preparations. --the near infrared reflection spectroscopy. The estimation of the energy value of raw ingredients is discussed more in detail. Formulas for the rapid calculation of the energy value of pulp and tubers are reported. The results obtained at the National Institute for Animal Nutrition in Melle-Gontrode with the two step in vitro digestion technique and a developed cellulase method are illustrated more in detail.

Effect of grain processing on in sacco digestibility and degradability in the rumen.

Effect on nylon-bag digestibility of rolling and steam-flaking as such or followed by grinding through a 1-mm screen was studied in wheat, barley and maize grains. Digestibilities of ground grains were not different, irrespective of rolling or steam-flaking, except flaked and ground barley, which was less digestible than ground barley. Rolled and flaked grains were less digestible than ground grains, except for rolled wheat which was not different from ground wheat. These results suggest that particle size due to grinding is more important than other methods of processing. Dry matter and protein degradabilities of steam-flaked grains were investigated by in sacco technique and compared with unprocessed grains. Dry matter degradability during incubation periods up to 24 h was reduced for steam-flaked wheat and barley, but increased for flaked maize. Protein degradability was lower for flaked grains.

Effect of virginiamycin on in vivo digestibility, rumen fermentation and nitrogen balance.

Three experiments were conducted to investigate the effect of virginiamycin. Digestibility was determined with wethers, fed a diet of 0.65 maize silage and 0.35 concentrate on a dry matter basis (Experiment I) or a complete dry feed (Experiment II) at maintenance, and with growing bulls fed a maize silage diet ad libitum supplemented with 7.5 g concentrate per kg live weight (Experiment III). Virginiamycin was incorporated at 0 or 65 ppm in the concentrate and 0 or 25 ppm in the complete dry feed. No significant effect on dry or organic matter digestibility was observed, although digestibilities of protein and ether extract were reduced by virginiamycin in experiments I and II, respectively. Rumen fermentation was studied in experiments I and II. Virginiamycin increased acetic acid concentration and reduced butyric acid concentration in experiment I, but exerted no significant effect in experiment II. An interaction between diet type and virginiamycin was found for the C2/C3 ratio. Nitrogen balance, measured in experiment III, was not affected by virginiamycin.

Response to virginiamycin in finishing beef bulls fed a maize silage diet or a complete dry feed.

Two experiments have been conducted to study the effect of virginiamycin in a maize silage diet (I) or a complete dry feed (II). Virginiamycin was incorporated at 0 or 65 mg per kg concentrate which was fed at 0.75% of the live weight of 43 Belgian white-red bulls (I), or at 0 or 25 mg per kg complete dry feed for 24 Belgian white-blue bulls (II). In the first experiment daily gain was increased by virginiamycin from 1.28 to 1.38 kg without effect on intake, but with an improved feed conversion from 5.99 to 5.60 kg dry matter/kg gain. In the second experiment daily gain, daily dry matter intake and feed conversion were not influenced by virginiamycin. The differences between experiments may suggest that the response to virginiamycin probably depends on the diet type, although no significant interaction was found between diet type and virginiamycin with regard to growth rate (P greater than 0.10). In both experiments, fasting weight loss, dressing percent and carcass classification and composition were not affected by virginiamycin.

[Effects of the addition of iso-acids to feed on ruminal fermentation, in sacco degradation of dry matter and the concentration of several blood parameters in cows]. / Effets de l'addition d'iso-acides à la ration sur la fermentation ruminale, la dégradation in sacco de la matière sèche et la concentration de quelques paramètres sanguins chez la vache.

Three rumen-fistulated cows fed maize silage and concentrates were supplemented with either soybean oil meal or urea, associated or not with isoacids. The isoacids increased the volatile fatty acid concentration, lowered the ruminal ammonia concentration and in sacco dry matter disappearance and did not influence blood parameters.

[Effect of cimaterol on nitrogen metabolism in fattening bullocks]. / Effet du cimatérol sur le métabolisme de l'azote chez des taurillons à l'engrais.

Nitrogen balance was studied in 5 bulls fed a concentrated diet containing 0 or 4 ppm cimaterol. Cimaterol increased nitrogen retention, mainly by reducing urinary nitrogen excretion due to decreased body protein degradation. There was a tendency for reduced nitrogen utilization efficiency when treatment was prolonged.

Effect of a ß-agonist on meat quality and myofibrillar protein fragmentation in bulls.

Three experiments were conducted to study the effect of cimaterol on meat quality and myofibrillar protein fragmentation of the Longissimus dorsi muscle. In two experiments (Experiments 1 and 2), conducted with 16 double-muscled Belgian white-blue bulls and 15 Charolais bulls, respectively, half of the animals received 60 µg cimaterol daily per kg liveweight in the diet, during 135 and 93 days, respectively. In a third experiment, 46 normal Belgian white-blue bulls received no or 4 ppm cimaterol in the diet for 246, 127 or 71 days on average. A withdrawal period of 6 days was always applied for cimaterol-treated animals. Ultimate pH, colour and waterholding capacity were not significantly affected. The effect of cimaterol on moisture content was variable, while protein content was increased and fat was reduced. Warner-Bratzler shear force values were increased by cimaterol P < 0·05 in Experiments 2 and 3 and P = 0·07 in Experiment 1). The lower tenderness cannot be explained by differences in sarcomere length or hydroxyproline content. Myofibrillar protein fragmentation was lower when cimaterol was fed, suggesting that cimaterol may reduce myofibrillar protein degradation via a lower activity of the proteolytic enzymes. Length of cimaterol administration only exerted minor effects on meat quality.

Structure and expression analyses of the S-adenosylmethionine synthetase gene family in Arabidopsis thaliana.

The plant, Arabidopsis thaliana, contains two S-adenosylmethionine synthetase-encoding genes (sam). Here, we analyze the structure and expression of the sam-2 gene and compare it with the previously described sam-1 gene. Northern-blot analysis using gene-specific probes shows that both sam-1 and sam-2 are highly expressed in stem, root, and callus tissue. This similar expression pattern might be mediated by the presence of three highly conserved sequences in the 5' region of both sam genes. Using a chimeric beta-glucuronidase (GUS)-encoding gene, we show that in transgenic tobacco plants, 748 bp of 5' sam-1 sequences generate high GUS activity in the same type of tissues as previously observed in transgenic A. thaliana plants. A deletion analysis of these 5' sam-1 sequences indicates that 224 bp of 5' sam-1 sequences can still induce higher expression of the gene in stem and root relative to leaf. However, the level of expression is reduced when compared to the expression level obtained with the full-length promoter.

Effect of purified immunoglobulins or pooled colostrum on performance of rearing calves.

Fifty Belgian white-blue male calves, purchased from the market at about 10 days of age, were divided into three groups. The basic diet was the same for all calves, and consisted of a restricted amount of commercial milk replacer containing 50 ppm zinc bacitracin and 20 pm virginiamycin, calf starter and grass hay. Weaning occurred when daily starter intake over 7 consecutive days averaged 0.5 kg. Maximum starter intake was restricted to 3 kg day-1, and grass hay was fed ad libitum. The experiment lasted 20 weeks. Group 1 (control) received the basic diet. Groups 2 and 3 were supplemented with either 2 g purified immunoglobulins (Ig) or 25-ml pooled colostrum (CO) twice daily, via the milk replacer as used in Group 1. Neither Ig nor CO exerted a positive effect on growth rate and feed efficiency. Six calves died: two, one and three in Groups 1, 2 and 3, respectively. Their serum IG content was significantly lower than that of the surviving animals. Mechanisms explaining the lack of any protective effect are discussed. It is supposed that the main reason was due to the gap between the CO feeding at birth and the onset of the administration of Ig or CO at the start of the experiment. At that time, 31 of the 50 calves excreted rota-and/or coronaviruses.

Long-term supplementation of lasalocid-sodium for beef bulls during grazing and subsequent finishing period.

117 white-red beef bulls were involved to investigate the effect of lasalocid-sodium when fed either during the grazing period, or the finishing period, or during both subsequent periods. The ionophore was fed at 250 mg daily per head incorporated in 1 kg dry sugar beet pulp on pasture and at 65 mg per kg concentrate afterwards (corresponding with 27 ppm in the ration DM). The finishing diet consisted of maize silage ad libitum and 0.75 kg concentrate per 100 kg liveweight per day. On pasture lasalocid significantly increased daily gain form 0.6 to more than 0.7 kg, without affecting the grazed area per animal. During the finishing period growth rate was only slightly affected by lasalocid, but feed intake was reduced (P less than 0.05) and feed conversion improved (P less than 0.05). Feeding lasalocid permanently for more than 400 days did not reduce these positive effects. Cumulative daily gain, total feed intake per head and feed conversion were 1.12 kg, 2176 kg dry matter (DM) and 4.70 kg DM. These figures amounted to 1.05 kg, 2283 kg DM and 5.16 kg DM when no lasalocid was fed; 1.06 kg, 2141 kg DM and 4.87 kg DM when lasalocid was only fed during the finishing period and 1.09 kg, 2246 DM and 4.99 kg DM when lasalocid was only fed during the grazing period. Daily gains of 1.05 and 1.06 kg were significantly lower (P less than 0.05) than 1.12 kg. Most carcass data were unaffected, except fatness. The permanent feeding of lasalocid increased carcass fatness, mainly as the result of a higher final weight.