Gunjan Goel

Methane mitigation from ruminants using tannins and saponins

MethanereductionontrulydegradedsubstratebasisOMD Organic matter digestibilityPSM Plant secondary metabolitesQSE Quillaja saponaria extractSCFAs Short-chain fatty acidsTP Total phenolsTT Total tanninsIntroductionThe ruminal methane production is a by-product of themicrobial digestive process and represents a loss of 2–12%of the feed energy. Furthermore, emission of methane isconsidered as one of the most important global environ-mental issues (IPCC 2001). Therefore, decreasing methaneproduction is desirable for reducing the greenhouse gasemission with improved efficiency of the digested energyutilization (Johnson and Johnson 1995). A previous reportby Kurihara et al. (1999) indicated that methane energy lossin cattle fed on tropical forage diets was higher than inthose fed on temperate forage diets, due to relative highlevels of fibre and lignin and a low level of non-fibrecarbohydrate in tropical forages. Also, the livestock indeveloping countries are predominantly maintained on ahigh-roughage diet with little or no concentrate resulting inincreased ruminal methanogenesis. Therefore, the use ofbrowse species containing secondary compounds as feedsupplement rich in plant secondary metabolites (PSM) forruminants in many parts of the tropics is increasing in orderto improve animal performance and reduce methane(Abdulrazak et al. 2000). Tannins and saponins constitutethe major classes of PSM that are currently under researchin a number of laboratories. The antimicrobial action andeffects on rumen fermentation of these compounds dependon their nature, activity and concentration in a plant or plant

Interaction of gut microflora with tannins in feeds

Tannins (hydrolyzable and condensed) are water-soluble polyphenolic compounds that exert antinutritional effects on ruminants by forming complexes with dietary proteins. They limit nitrogen supply to animals, besides inhibiting the growth and activity of ruminal microflora. However, some gastrointestinal microbes are able to break tannin–protein complexes while preferentially degrading hydrolyzable tannins (HTs). Streptococcus gallolyticus, Lonepinella koalarum and Selenomonas ruminantium are the dominant bacterial species that have the ability to degrade HTs. These tanninolytic microorganisms possess tannin-degrading ability and have developed certain mechanisms to tolerate tannins in feeds. Hence, selection of efficient tanninolytic microbes and transinoculation among animals for long-term benefits become areas of intensive interest. Here, we review the effects of tannins on ruminants, the existence and significance of tannin-degrading microorganisms in diverse groups of animals and the mechanisms that tannin-degrading microorganisms have developed to counter the toxic effects of tannin.

Molecular beacon : a multitask probe

The specificity of hybridization of complementary sequences in DNA is the basic strategy for identifying target genes. For this, stem loop oligonucleotide probes have been developed in order to enhance the specificity and selectivity to the target DNA. Among stem loop oligonucleotides, molecular beacons are the recent probes used for biomolecular recognition reactions. Molecular beacon-based assays are fast, simple, inexpensive, and enable real-time monitoring of nucleic acid reactions both, in vivo and in vitro. This review has been designed to provide a better understanding of the different aspects of molecular beacons, e.g. structure, designing and applications in real-time monitoring of nucleic acid amplification, detection of pathogens, nucleic acid–protein interaction, genetic analysis and array technology.

Myco-Biocontrol of Insect Pests: Factors Involved, Mechanism, and Regulation

The growing demand for reducing chemical inputs in agriculture and increased resistance to insecticides have provided great impetus to the development of alternative forms of insect-pest control. Myco-biocontrol offers an attractive alternative to the use of chemical pesticides. Myco-biocontrol agents are naturally occurring organisms which are perceived as less damaging to the environment. Their mode of action appears little complex which makes it highly unlikely that resistance could be developed to a biopesticide. Past research has shown some promise of the use of fungi as a selective pesticide. The current paper updates us about the recent progress in the field of myco-biocontrol of insect pests and their possible mechanism of action to further enhance our understanding about the biological control of insect pests.

In vitro degradation of wheat straw by anaerobic fungi from small ruminants

Abstract Anaerobic ruminal fungi may play an active role in fibre degradation as evidenced by the production of different fibrolytic enzymes in culture filtrate. In the present study, 16 anaerobic fungal strains were isolated from ruminal and faecal samples of sheep and goats. Based on their morphological characteristics they were identified as species of Anaeromyces, Orpinomyces, Piromyces and Neocallimastix. Isolated Neocallimastix sp. from goat rumen showed a maximum activity of CMCase (47.9 mIU ml−1) and filter paper cellulase (48.3 mIU ml−1), while Anaeromyces sp. from sheep rumen showed a maximum xylanolytic activity (48.3 mIU ml−1). The cellobiase activity for all the isolates ranged from 178.0 – 182.7 mIU ml−1. Based on the enzymatic activities, isolated Anaeromyces sp. from sheep rumen and Neocallimastix sp. from goat rumen were selected for their potential of in vitro fibre degradation. The highest in vitro digestibility of NDF (23.2%) and DM (34.4%) was shown for Neocallimastix sp. from goat rumen, as compared to the digestibility of NDF and DM in the control group of 17.5 and 25.0%, respectively.

Insights into virulence factors determining the pathogenicity of Cronobacter sakazakii

Cronobacter sakazakii is an opportunistic pathogen associated with outbreaks of life-threatening necrotizing enterocolitis, meningitis and sepsis in neonates and infants. The pathogen possesses an array of virulence factors which aid in tissue adhesion, invasion and host cell injury. Although the identification and validation of C. sakazakii virulence factors has been hindered by availability of suitable neonatal animal model, various studies has reported outer membrane protein A (ompA) as a potential virulence marker. Various other plasmid associated genes such as filamentous hemagglutinin (fhaBC), Cronobacter plasminogen activator (cpa) and genes responsible for iron acquisition (eitCBAD and iucABD/iutA) have been reported in different strains of C. sakazakii. Besides these proposed virulence factors, several biophysical growth factors such as formation of biofilms and resistance to various environmental stresses also contributes to the pathogenic potential of this pathogen. This review provides an update on virulence determinants associated with the pathogenesis of C. sakazakii. The potential reservoirs of the pathogen, mode of transmission and epidemiology are also discussed.

Production of tannase through solid state fermentation using Indian Rosewood ( Dalbergia Sissoo )sawdust—a timber industry waste

The tannase producing strain Aspergillus heteromorphus MTCC 8818 was used in the present study for the production of tannase under solid state fermentation using Rosewood (Dalbergia sissoo) sawdust—a timber industry waste—as substrate. Various physico-chemical parameters were optimized for extracellular yield of tannase. Maximum tannase (1.84 U/g dry substrate) and gallic acid (5.4xa0mg/g ds) was observed at 30xa0°C after 96xa0h of incubation. Czapek dox medium was found to be the best moistening agent, with pH and relative humidity of 5.5 and 70xa0%, respectively. The constituents of Czapek dox medium were varied to enhance enzyme production. The optimum concentration of modified Czapek dox constituents contained 0.2xa0% NaNO3, 0.05xa0% K2HPO4 and MgSO4, 0.15xa0% KCl. Among the additional salts supplemented to Czapek dox medium, ZnSO4 and CuSO4 were found to have a stimulating effect, with a relative tannase activity of 116 and 111xa0%, respectively. Glucose as an external carbon source was found to be a repressor of enzyme production.