Research Rept. Biotechnical Fac. University of Ljubljana Agricultural Issue. Zootechnica 72(1998)

SENSORY CHARACTERISTICS FOR POULTRY MEAT OF DIFFERENT HYBRIDS

R. VADNJAL^a), Antonija HOLCMAN, Milena KOVAČ, Lea GAŠPERLIN, B. ŽLENDER
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
The effect of provenance of chickens, sex of animals and parts of meat (legs vs. breasts) on sensory and instrumental parameters of meat quality was studied. Three foreign provenances (Arbor Acres, Avian and Ross) and two domestic hybrids (Prelux-bro1 and Prelux-bro2) were fattened in cages to the age 47 days. Eight animals from each group (4 female, 4 male) were chosen for analysis. After roasting (Tm = 80^o C) meat from breasts and legs was sensory analysed (colour, flavour and texture) was instrumentally measured by INSTRON apparatus as cutting value-across (CVAc) and -along (CVAl). Statistically significant effect of provenance on the smell and flavour was established. They were the lowest in Ross hybrid, yet its meat contained the most fat and had the best tenderness. Sensory parameters for male meat were higher than for female one while values for juiciness, fatness and mouth feeling differed significantly. Breasts had higher CVAc and CVAl values in comparison to legs, which was in accordance with lower sensory evaluated tenderness. Breasts had higher values for colour and smell in comparison to legs, while juiciness, fatness and mouth felling had lower values. Significant correlations were established between instrumental parameters and sensory parameters for the texture of meat.

Key words: poultry / genetics / provenance / meat / quality / instrumental parameters / sensory parameters

 

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SENSORY CHARACTERISTICS OF THE WHOLE THERMAL TREATED CHICKENS OF DIFFERENT PROVENANCE

B. ŽLENDER^a), Antonija HOLCMAN, Alenka RAJAR, R. VADNJAL, Milena KOVAČ
^a) Univ. of Ljubljana, Biotechnical Fac., Dept. Food Sci. Tech., Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
The aim of the study was to investigate the effect of provenance of fattened chickens and sex of animals on sensory quality of whole chickens after the thermal treatment. Eight chickens (4 female and 4 male) of three foreign provenances, Arbor Acres (AA), Avian (A), Ross (R) and two crossbred of domestic provenance Prelux-bro1 (PB1) and Prelux-bro2 (PB2), were examined. After slaughtering and freezing chickens were thermally treated by roasting at 190^o C till the temperature in the breast was Tc = 80^o C. Whole chickens were sensory analyzed: colour, texture, fatness and flavour of skin, while common impression was determined after the complete analysis of legs and breasts. Results showed that the provenance of chickens significantly affected the colour and common impression and to some extent fatness of skin. The best colour was found in chickens A and the worst in PB1 which were the least fat. Texture and flavour of skin of roasted chickens were not affected by provenance of chickens. Male chickens were assessed better that female at all sensory traits except the flavour of skin, which did not differ between sexes. The effect of assessors on estimations of sensory characteristics was evidently significant.

Key words: poultry / chickens / genetics / provenance / meat / skin / thermal treatment / sensory parameters

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 SUPERANTIGENS

Mojca NARAT^a)
a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Review article
Language: English

ABSTRACT
Superantigens are bacterial, viral, retroviral and some naturally occurring proteins that can specifically activate a large proportion of T and/or B cells. In contrast to classical peptide antigen recognition, superantigens do not require processing to small peptides. T-cell superantigens interact with the immune system by binding to major histocompatibility complex (MHC) class II proteins outside the classical antigen binding groove and activate T cells through the variable region of the T cell receptor beta-chain. B-cell superantigens target B cells, which have restricted usage of variable heavy and light chain and by binding to immunoglobulins outside the conventional antigen binding site, stimulate a high frequency of B cells. Studies of T-cell and B-cell superantigens are important since they are involved in many human diseases and represent a great tool in unravelling some of the basic mechanisms of immune response.

Key words: immunology / microbiology / superantigens / T cells / B cells

 

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THE INFLUENCE OF Bacillus subtilis PROTEINS DegU, SinR AND SinIR ON BACITRACIN BIOSYNTHESIS IN Bacillus licheniformis

A. GASPARIČ^a), Tina DULAR, Alenka GROŠEL, G. SLADIČ, I. RADEŽ and Ines MANDIČ MULEC
^a) Krka, Pharmaceutical, Šmarješka cesta 6, SI-8000 Novo mesto, Slovenia

Original scientific paper
Language: English

ABSTRACT
A vast array of natural peptides diverse in their structure that are produced by microorganisms living in different aquatic and terrestrial environments are not gene encoded but are synthetized nonribosomally on peptide synthetases. The branched cyclic dodecyl peptide antibiotic bacitracin, produced by special strains of Bacillus, is synthesized nonribosomally by a large multienzyme complex composed of the three bacitracin synthetases BA1, BA2 and BA3. The rate of peptide antibiotic bacitracin biosynthesis positively correlates with the level of the alkaline protease production. To define some positively acting factors in terms of bacitracin production we performed an experiment expressing genes involved in the process of sporulation and competence (B. subtilis): degU on pBD1834, sinIR on pIS74 and sinR on pIS119 in B. licheniformis. Bacterial clones were analyzed for the proteolytic activity and bacitracin production. In 9 clones (2 x pBD1834, 2 x pIS74 in 5 x pIS119) higher rate of the peptide antibiotic bacitracin production was determined.

Key words: microbiology / bacteria / Bacillus / antibiotics / bacitracin / biosynthesis

 

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NUTRITION OF DAIRY COWS IN SUMMER AND NITROGEN EXCRETION

Marija RAJČEVIČ^a), Jasna M. A. STEKAR, J. ŽLINDRA, J. LEVSTEK
^a) Ulica bratov Učakar 6, SI-1117 Ljubljana, Slovenia

Original scientific paper
Language: English

ABSTRACT
Nutrition and production of 200 Friesian cows, which produced 24 kg milk a day, were monitored during five summer months. In September, the amount of total non-protein and ammonia nitrogen were determined in faeces, which were taken from ten cows' recta, and in slurry. A model of regression equations, which were introduced by Kirschgessner et al. (1993), was used to estimate daily amount of excreted nitrogen depending on few parameters. Cows excreted on average 301 g nitrogen a day depending on average consumed dry matter, depending on average consumed nitrogen 341 g, and depending on daily amount of milk 271 g. Faeces contained 34.04 ± 1.69 g total, 6.36 ± 0.76 g non-protein and 2.07 ± 0.33 g ammonia nitrogen, slurry contained 96.77 g total, 72.22 g non-protein and 57.15 g ammonia nitrogen, all per kg of dry matter. Protein surpluses in a ration reflected in more excreted nitrogen by urine while only in traces by faeces.

Key words: cattle / cows / dairy cows / animal nutrition / summer nutrition / nitrogen / excrements

 

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THE EFFECT OF MAIZE GRAIN TYPE ON DIGESTIBILITY OF STARCH IN THE RUMEN OF SHEEP

J.(Jože) VERBIČ^a), D. BABNIK, Vida ŽNIDARŠIČ-PONGRAC
^a) Kmetijski inštitut Slovenije, Hacquetova 17, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: English

ABSTRACT
Ruminal starch digestibility of dried maize grain and whole plant maize silage was determined by the in sacco method. It was found out that starch of dent type maize hybrid is more extensively digested in the rumen than starch of flint type hybrid. Digestibilities of dried maize grain from dent and flint type hybrids were 683 and 554 g kg^-1 respectively. Ruminal digestibilities of corresponding silages were 915 and 743 g kg^-1. Ruminal digestibility of starch in whole plant maize silage was on average about 200 g kg^-1 higher than in dried grain samples. Ruminal starch digestibility of maize silages can not be estimated directly on the basis of measurements done on dried grain samples. Some practical implications of differences among hybrids and between dried and ensiled maize are discussed.

Key words: sheep / animal nutrition / feed / maize / grain / silage / starch / rumen / digestibility

 

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NUMBER AND HETEROGENEITY OF rRNA OPERONS IN RUMEN BACTERIAL MEMBERS FROM THE GENUS Prevotella

M. PETERKA^a) and G. AVGUŠTIN
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
The number of rRNA operons and internal spacer region heterogeneities in members of the rumen genus Prevotella were analysed. Chromosomal DNA from 20 strains belonging to P.ruminicola, P.albensis, P.bryanti and P.brevis was isolated, digested by five restriction enzymes, and hybridized with 16S and 23S rDNA probes. The resulting hybridization patterns indicate that P. albensis strains possess 4 or 5 rRNA operons, strains belonging to P. brevis possess 4 rRNA operons and P. bryantii strains 6 or 7 rRNA operons. Strains belonging to P. ruminicola probably possess 4 rRNA operons, with one exception having 6 or 7 rRNA operons. 16S-23S spacer region was also PCR amplified. The results suggest that there are at least three size variable 16S-23S spacer regions in P. albensis and P. brevis, two in P. ruminicola, and only one spacer region in P. bryantii.

Key words: microbiology / molecular genetic / bacteria / Prevotella / rRNA operon / internal spacer region / rumen

 

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XYLANOLYTIC ENZYME SYSTEM OF RUMEN BACTERIUM Prevotella bryantii B₁4

Romana MARINŠEK LOGAR^a), A. GASPARIČ and F. V. NEKREP
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
Prevotella spp. are recognised as one of the most numerous strictly anaerobic bacteria inhabiting the rumen. Potentially significant activities include the degradation of plant cell wall polysaccharides, starch, proteins and peptides. P. bryantii B₁4 is not cellulolytic but actively degrades hemicellulose xylan and carries multiple xylanase genes. Four regions encoding xylanase activity have been isolated, one of which encodes a previously isolated CMC-ase. Of the remaining regions, one encodes activities against p-nitrophenyl-b -xyloside and p-nitrophenyl-a -L-arabinofuranoside (genes xyn A and xynB). The gene xynC encodes another endoxylanase. SDS PAGE xylanograms revealed four endoxylanolytic bands at 29 kDa, 45 kDa, 66 kDa and 88 kDa. The majority of endoxylanase and CMC-ase activity was found in periplasmic cell fraction while most of the a -L-arabinofuranosidase and b -xylosidase activities were found in the crude membrane fraction. HPLC separation of periplasmic proteins by CIM DEAE 8 tubes resulted in partial isolation of CMC-ase and 66-kDa endoxylanase.

Key words: microbiology / bacteria / Prevotellabryantii / enzymes / xylanases / rumen

 

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MICROBIAL DIVERSITY AND THE MODERN APPROACH TO THE INVESTIGATION OF COMPLEX MICROBIAL ECOSYSTEMS

G. AVGUŠTIN^a)
a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Review paper
Language: English

ABSTRACT
Our knowledge about microbial diversity has been rapidly accumulating due to the application of the modern molecular biology based techniques. DNA sequence based taxonomy and phylogenetic studies were among the first that implemented molecular biology techniques but the field of microbial diversity seems to be the one that will profit most. Traditional estimations of the numbers of different microorganisms inhabiting our planet have been surpassed by the first molecular screenings of the natural microbial ecosystems and while everybody agrees that the known microorganisms can only represent a minor share of planetary microbiota, nobody can really estimate the actual size of it. Techniques that are not tied to the isolation and cultivation procedures are the only ones that could make progress in the field. A review of the history of implementation of molecular biology methods in microbiology is presented.

Key words: microbiology / microbial diversity / molecular biology / phylogenetics

 

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PHYLOGENETIC DIVERSITY OF BACTERIAL POPULATION IN RUMEN

Andreja RAMŠAK^a*) and G. AVGUŠTIN
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia
^*present address: Friškovec 2, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: English

ABSTRACT
In order to investigate the microbial diversity in rumen, bacterial 16S rRNA genes were amplified from total microbial DNA isolated from rumen fluid. The amplificated genes were incorporated into pBluescript SK II vector and electroporated into E.coli JM109 cells. The transformants, recognized in hybridization experiments (colony blot) by oligonucleotide DNA probe specific for the Cytophaga-Flavobacterium subgroup of the Cytophaga-Flexibacter-Bacteroides phylum and Prevotella-Bacteroides specific probe, were subjected to the RFLP analysis. On the basis of the RFLP profiles the Jaccard’s similarity coefficients were calculated and the dendrograms were created using the UPGMA method. The representative clones were chosen from the established groups of clones and the 16S rDNA was partially sequenced, compared to already known rRNA sequences in data banks and analysed using Clustal and Phylip phylogenetic packages. A large genetic variability of the rumen bacteria belonging to the Cytophaga-Flexibacter-Bacteroides phylum was established.

Key words: microbiology / bacteria / molecular genetic / rRNA / phylogeny / rumen

 

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CHITINOLYTIC ENZYMES IN THE RUMEN MICROBIAL ECOSYSTEM

J. KOPEČNÝ^a) and Blanka HODROVÁ
^a) Czech Academy of Sciences, Institute of Animal Physiology and Genetics, Prague 10, Uhříněves, 104 00, Czech Republic

Original scientific paper
Language: English

ABSTRACT
Chitinolytic systems of rumen Clostridia (usually the most active rumen chitinolytic bacteria) and rumen anaerobic fungi were compared in the present study. The chitinolytic enzymes of tested Clostridia strains were represented mainly by extracellular exochitinases, N-acetylglucosaminidases, chitin deacetylases and chitosanases. Zymograms of exochitinases revealed that these enzymes were bound in complexes with MW higher than 100 kDa. Final products of chitin degradation were glucosamine, N-acetylglucosamine and chitin oligosaccharides. Fungal chitinases were represented mainly by extracellular endochitinases and chitin deacetylase in both mono- and polycentric fungi. The main activities in cellular fraction were chitosanase and endochitinase. There were no or low activity of N-acetylglucosaminidase activity in all fungal strains tested. In comparison with rumen chitinolytic bacteria there was lower production of exochitinases and no production of N-acetylglucosaminidase in rumen fungi.

Key words: microbiology / bacteria / Clostridium / fungi / enzymes / chitinolysis / rumen

 

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MOLECULAR GENOTYPING OF RUMEN FUNGI BASED ON RFLP ANALYSIS

Kateřina FLIEGEROVÁ^a), Sylva PAŽOUTOVÁ and Blanka HODROVÁ
^a) Czech Academy of Sciences, Institute of Animal Physiology and Genetics, Prague 10, Uhříněves, 104 00, Czech Republic

Original scientific paper
Language: English

ABSTRACT
Eight polycentric strains of the genera Orpinomyces and five monocentric strains of the genera Neocallimastix were examined for the restriction fragment length polymorphisms. EcoRI-digested nuclear DNA of isolates of rumen fungi and DNA-DNA hybridization with probe RS2 revealed several distinct cleavage profiles. Results are ambiguous and interpretation is difficult with respect to the high genetic variability of rumen fungi isolates.

Key words: microbiology / anaerobic fungi / molecular genetics / RFLP / classification / rumen

 

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ANALYSIS OF COMPLEX MICROBIAL ECOSYSTEMS WITH IN SITU HYBRIDIZATION AND EPIFLUORESCENT MICROSCOPY

Katarina TEPŠIČ^a) and G. AVGUŠTIN
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
In situ hybridization with fluorescent oligonucleotide probes combined with epifluorescent microscopy was used to detect and localize microorganisms in rumen samples from a black and white Friesian cow. Bacterial cells were hybridized with 16S rRNA targeted oligonucleotide probes specific for the phylogenetic group Cytophaga-Flexibacter-Bacteroides (CFB) (BACPRE) and for species Prevotella bryantii B₁4 (PBB₁4) and P.ruminicola 23^T (PR23). The oligonucleotide probes were labelled with fluorescine isothiocyanate (FITC) or tetramethylrodamine isothiocyanate (TRITC). Both species specific probes proved to be highly specific and gave strong and clear signal.

Key words: microbiology / bacteria / Prevotella / molecular biology / In situ hybridization / epifluorescent microscopy / rumen

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GENETIC CHARACTERIZATION OF LF221 ACIDOCINS

Andreja ČANŽEK MAJHENIČ^a) and Irena ROGELJ
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
Acidocin LF221 A and B are at least two different bacteriocins produced by Lactobacillus acidophilus LF221. In previous research work the N-terminal amino acid (AA) sequence was determined from the purified peptides and probes for both acidocins were prepared as well. Southern hybridization was used to locate structural genes for acidocin LF221 A and B on the genome. Using as a template digested chromosomal DNA of either LF221 or its bac^- derivative, identical results were obtained. A possible explanation for this is that bac^- mutant still contains the structural genes for both acidocins. When acidocin LF221 A or B were compared to other known bacteriocins, they showed some homology to ThmB peptide of thermophilin 13 or LafX peptide of lactacin F. We assume that LF221 acidocins are novel representatives of the class II bacteriocins.

Key words: microbiology / bacteria / Lactobacillus acidophilus / bacteriocins / molecular genetics / cloning / classification

 

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BACTERIOCINS OF Lactobacillus LF221 STRAIN

Bojana BOGOVIČ MATIJAŠIĆ^a) and Irena ROGELJ
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
LF221 strain is a Lactobacillus isolate from a baby’s faeces that was previously found to produce bacteriocin(s) with inhibitory activity against a wide range of bacterial species including some pathogenic and food-spoilage (Bacillus cereus, Clostridium sp., Listeria innocua, Staphylococcus aureus). Isoelectric point and molecular mass of bacteriocin complex and subunits were estimated. Precipitation with ammonium sulphate, cation exchange chromatography, C₈ hydrophobic interaction chromatography and reverse-phase FPLC chromatography were used to isolate bacteriocins from the supernatant of MRS culture. Amino acid composition and partial N-terminal amino acid sequences of two isolated bacteriocins were determined. Bacteriocins were present in MRS supernatant as aggregates with Mw>150.000 and pI 5.1-5.3, while Mw of subunits was 3500-5000. A high content of glycin and alanin was observed for both bacteriocins. The N-terminal amino acid sequences showed little similarity with those of other bacteriocins. Acidocins LF221 A and B appear to belong to the II class of LAB bacteriocins.

Key words: microbiology / bacteria / Lactobacillus / bacteriocins / classification

 

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SPECIFIC DETECTION OF Salmonella spp. WITH MOLECULAR BIOLOGICAL TECHNIQUES

Marija TRKOV^a) and G. AVGUŠTIN
^a) Univ. of Ljubljana, Biotechnical Fac., Dept. Food Sci. Tech., Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: English

ABSTRACT
A method for specific detection of Salmonella spp. was developed based on 16S rRNA targeted PCR (polymerase chain reaction). A method based on recognition of specific region of 16S rRNA gene was published previously by Lin and Tsen in 1996. The sequence analysis of recently determined small subunit ribosomal genes from Salmonella spp. showed however, that the 16SF1 and 16SIII primers are not suitable for specific amplification of all Salmonella strains. 16SF1 was modified and a new forward PCR primer was designed. The specificity of the method was tested using 87 Salmonella strains and 30 non-Salmonella strains of the family Enterobacteriaceae and compared with two other previously published methods and found to be 100% specific. The reverse primer was also labelled with a tetramethylrhodamine isothyiocianate fluorescent dye and successfully used as a probe in in situ experiments.

Key words: microbiology / bacteria / Salmonella / molecular biology / methods / molecular genetic / rRNA

 

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MOLECULAR IDENTIFICATION AND CHARACTERIZATION OF AVIAN MYCOPLASMAS

P. DOVČ^a) and D. BENČINA
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Review paper
Language: English

ABSTRACT
Serological techniques are recommended procedures for the identification of Mycoplasma species. They enable separation of mycoplasmas at the species level and are widely used for practical laboratory identification of the isolated microorganisms. However, complex growth media are required for the isolation of Mycoplasma species and some strains of pathogenic Mycoplasma species grow very fastidious and can not be cultured. Introduction of DNA based diagnostic methods in mycoplasma research enabled survey of the whole genome in a single assay and reveal also information about non-coding regions of the genome. Restriction enzyme analysis is a powerful method for differentiation of close related strains but requires high quality of DNA which can only be obtained from cultured mycoplasmas. The increasing number of cloned mycoplasma genomic fragments are successfully used for identification and differentiation of mycoplasma strains and species in hybridization studies. The polymerase chain reaction enables identification and characterization of mycoplasmas without culture directly from clinical material. Large genomic sequencing projects produced complete nucleotide sequence from two Mycoplasma species and several more are in progress. This data will open the possibility to understand better the biology of mycoplasmas.

Key words: microbiology / mycoplasma / diagnostics / molecular genetic / DNA / polymerase chain reaction

 

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VARIABLE DNA SEQUENCE OF THE pMGA GENE IN Mycoplasma gallisepticum

Tamara MILOŠEVIČ BERLIČ^a), D. BENČINA and P. DOVČ
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
Specific fragments of Mycoplasma gallisepticum genomic DNA, representing different regions of pMGA1.1 and pMGA1.2 genes, were amplified by Polymerase Chain Reaction (PCR). Using sequence analysis of pMGA terminal domains, differences in nucleotide sequences among strains of M. gallisepticum were identified. Restriction analysis revealed polymorphism at the 5? -end of the pMGA coding region. By means of sequence analysis it was established that the most variable part of pMGA sequence was the 5? -end of the pMGA gene, the region coding amino-terminal part of pMGA protein, while the 3? -end of the gene was conserved among various M. gallisepticum strains analysed. In some strains insertions or deletions were found that indicate the diversity of the pMGA gene family and might be related to the variable expression of the pMGA gene family. Changes in nucleotide sequences of the pMGA genes were also found within isogenic lineages. Genotypic variability is also confirmed by results of the study of the gene product expression.

Key words: microbiology / mycoplasma / Mycoplasmagallisepticum / molecular genetics / genes / pMGA / sequencing

 

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