A.K. Samanta

Enzymatic production of xylooligosaccharides from alkali solubilized xylan of natural grass (Sehima nervosum).

In this study, a process for producing XOS from Sehima nervosum grass was developed. The grass contains 28.1% hemicellulose. NaOH and steam application yielded 98% of original xylan in contrast to 85% by KOH application. Hydrolysis of xylan with commercial xylanase caused breakdown into XOS comprising of xylobiose, xylotriose along with xylose. Response surface model (RSM) revealed highest xylobiose yield (11 g/100g xylan) at pH 5.03, temperature 45.19°C, reaction time 10.11h with enzyme dose 17.41 U. Similarly for maximizing xylotriose yield, ideal hydrolysis conditions were pH 5.11, temperature 40.33°C, reaction time 16.55 h with enzyme dose 13.20 U. A two step process encompassing xylan fractionation and enzymatic hydrolysis enabled XOS production from the S. nervosum grass.

Prebiotic inulin: Useful dietary adjuncts to manipulate the livestock gut microflora

In recent years, there has been a growing appreciation on the relevance of gastrointestinal microflora in both ruminants and non-ruminants owing to revelation of their role in several physiological functions including digestion, nutrient utilization, pathogen exclusion, gastrointestinal development, immunity system, gut gene expression and quality of animal products. The ban imposed on the use of antibiotics and hormones in feed has compelled animal researchers in finding an alternative which could overcome the issues of conventional feed additives. Though the concept of prebiotic was evolved keeping in mind the gastrointestinal flora of human beings, presently animal researchers are exploring the efficiency of prebiotic (inulin) for modulating the gut ecosystem of both ruminants and non-ruminants. It was revealed that prebiotic inulin is found to exhibit desirable changes in the gut of non-ruminants like poultry, swine, rabbit etc for augmenting gut health and improvement of product quality. Similarly, in ruminants the prebiotic reduces rumen ammonia nitrogen, methane production, increase microbial protein synthesis and live weight gains in calves. Unlike other feed additives, prebiotic exhibits its effect in multipronged ways for overall increase in the performances of the animals. In coming days, it is expected that prebiotics could be the part of diets in both ruminants and non-ruminants for enabling modulation of gut microflora vis a vis animals productivity in ecological ways.

Value addition of corn husks through enzymatic production of xylooligosaccharides

Corn husks are the major wastes of corn industries with meagre economic significance. The present study was planned for value addition of corn husk through extraction of xylan, followed by its enzymatic hydrolysis into xylooligosaccharides, a pentose based prebiotic. Compositional analysis of corn husks revealed neutral detergent fibre 68.87%, acid detergent fibre 31.48%, hemicelluloses 37.39%, cellulose 29.07% and crude protein 2.68%. Irrespective of the extraction conditions, sodium hydroxide was found to be more effective in maximizing the yield of xylan from corn husks than potassium hydroxide (84% vs. 66%). Application of xylanase over the xylan of corn husks resulted into production of xylooligosaccharides with different degree of polymerization namely, xylobiose and xylotriose in addition to xylose monomer. On the basis of response surface model analysis, the maximum yield of xylobiose (1.9 mg/ml) was achieved with the enzymatic hydrolysis conditions of pH 5.8, temperature 44°C, enzyme dose 5.7U/ml and hydrolysis time of 17.5h. Therefore, the corn husks could be used as raw material for xylan extraction vis a vis its translation into prebiotic xylooligosaccharides.

Assessment of Fecal Microflora Changes in Pigs Supplemented with Herbal Residue and Prebiotic

Antibiotic usage in animals as a growth promoter is considered as public health issue due to its negative impact on consumer health and environment. The present study aimed to evaluate effectiveness of herbal residue (ginger, Zingiber officinale, dried rhizome powder) and prebiotic (inulin) as an alternative to antibiotics by comparing fecal microflora composition using terminal restriction fragment length polymorphism. The grower pigs were offered feed containing antibiotic (tetracycline), ginger and inulin separately and un-supplemented group served as control. The study revealed significant changes in the microbial abundance based on operational taxonomic units (OTUs) among the groups. Presumptive identification of organisms was established based on the fragment length of OTUs generated with three restriction enzymes (MspI, Sau3AI and BsuRI). The abundance of OTUs representing Bacteroides intestinalis, Eubacterium oxidoreducens, Selonomonas sp., Methylobacterium sp. and Denitrobacter sp. was found significantly greater in inulin supplemented pigs. Similarly, the abundance of OTUs representing Bacteroides intestinalis, Selonomonas sp., and Phascolarcobacterium faecium was found significantly greater in ginger supplemented pigs. In contrast, the abundance of OTUs representing pathogenic microorganisms Atopostipes suicloacalis and Bartonella quintana str. Toulouse was significantly reduced in ginger and inulin supplemented pigs. The OTUs were found to be clustered under two major phylotypes; ginger-inulin and control-tetracycline. Additionally, the abundance of OTUs was similar in ginger and inulin supplemented pigs. The results suggest the potential of ginger and prebioticsto replace antibiotics in the diet of grower pig.

In Silico evaluation and identification of fungi capable of producing endo-inulinase enzyme

The enzyme endo-inulinase hydrolyzes inulin to short chain fructooligosaccharides (FOS) that are potential prebiotics with many health promoting benefits. Although the raw materials for inulin production are inexpensive and readily available, commercial production of FOS from inulin is limited due to inadequate availability of the enzyme source. This study aimed to identify the fungi capable of producing endo-inulinase based on the in silico analysis of proteins retrieved from non-redundant protein sequence database. The endo-inulinase of Aspergillus ficuum was used as reference sequence. The amino acid sequences with >90% sequence coverage, belonging to different fungi were retrieved from the database and used for constructing three-dimensional (3D) protein models using SWISS-MODEL and Bagheerath H. The 3D models of comparable quality as that of the reference endo-inulinase were selected based on QMEAN Z score. The selected models were evaluated and validated for different structural and functional qualities using Pro-Q, ProSA, PSN-QA, VERIFY-3D, PROCHECK, PROTSAV metaserver, STRAP, molecular docking, and molecular dynamic simulation analyses. A total of 230 proteins belonging to 53 fungal species exhibited sequence coverage >90%. Sixty one protein sequences with >60% sequence identity were modeled as endo-inulinase with higher QMEAN Z Score. The evaluations and validations of these 61 selected models for different structural and functional qualities revealed that 60 models belonging to 22 fungal species exhibited native like structure and unique motifs and residues as that of the reference endo-inulinase. Further, these models also exhibited similar kind of interaction between the active site around the conserved glutamate residue and substrate as that of the reference endo-inulinase. In conclusion, based on the current study, 22 fungal species could be identified as endo-inulinase producer. Nevertheless, further biological assessment of their capability for producing endo-inulinase is imminent if they are to be used for commercial endo-inulinase production for application in FOS industry.

Tagatose as a Potential Nutraceutical: Production, Properties, Biological Roles, and Applications: d-Tagatose as a nutraceutical…

Nutraceuticals are gaining importance owing to their potential applications in numerous sectors including food and feed industries. Among the emerging nutraceuticals, d-tagatose occupies a significant niche because of its low calorific value, antidiabetic property and growth promoting effects on beneficial gut bacteria. As d-tagatose is present in minute quantities in naturally occurring food substances, it is produced mainly by chemical or biological means. Recently, attempts were made for bio-production of d-tagatose using l-arabinose isomerase enzyme to overcome the challenges of chemical process of production. Applications of d-tagatose for maintaining health and wellbeing are increasing due to growing consumer awareness and apprehension against modern therapeutic agents. This review outlines the current status on d-tagatose, particularly its production, properties, biological role, applications, and the future perspectives.

Rumen Metagenomics and Its Implications in Animal Nutrition: A Review

The potential of metagenomics has paved way for studying yet to be cultured microbes, their abundance and functional capabilities in rumen ecosystem. Metagenomic techniques identified several new phyla in the domain bacteria. Rumen, being dominated by majority of yet to be cultured microbes, has not been aloof from application of metagenomics. The techniques available for studying microbial diversity without the need to cultur ethem are basically divided into low throughput and high throughput methods. The low throughput methods are cheaper and do not require costly infrastructure but have limited power to resolve the microbial community members. On the contrary, the high throughput methods based on next generation sequencing technologies offer tremendous potential to investigate the microbial diversity and functional capabilities. Studies in rumen metagenomics has revealed discovery of several enzymes, antibiotic resistance genes, antibiotics, metabolic and xenobiotic degrading pathways apart form understanding the ecosystem and its effect on nutrition and general health. The article discusses different techniques involved in rumen metagenomic investigation, applications in understanding microbial community dynamics under different dietary regimes, development and establishment of microflora, nutrition, methane mitigation, productivity etc.

Effect of Lignin Peroxidases Obtained From White Rot Fungi in Delignification of Cereal Crop Residues for Ruminant Feeding : Changes in Chemical Composition And in Vitro Digestibility.

Crop residues are renewable sources of energy for ruminants. Pre-digestion of such materials with ligninases from white rot fungi may transform the lignocellulosic substrate into a feed with greater digestibility and higher quality for ruminants. This study has evaluated the effect of crude (T1) and purified(T2) lignin peroxidase (LiP) obtained from immobilized white rot fungi (LPS1) on chemical composition and in vitro digestibility of nine cereal crop residues commonly used for feeding ruminants. Untreated straw served as control(C). Each straw was hand chaffed into 2.3 to 3.0 cm bit length and treated with the enzyme by spraying at a ratio of 1:2.5 and left for 24 h before analysis. Significant P and F values at 99% CI respectively were obtained in case of ADF, NDF and ADL with both T1 and T2. Also in vitro digestibility of dry matter (IVDMD) increased significantly in both T1 and T2. Highest increase of 20 % in IVDMD was obtained upon treatment of BRM, FXM and PRM with purified lignin peroxidase (T2) while LM showed the lowest of 12.34 % . T2 thus showed higher digestibility than T1 for all the crops as shown by LS means. Correlation graph with digestibility on Y-axis and lignin degradation on X-axis showed a strong negative correlation for all the crop residues used with increase in digestibility giving a linear decrease in lignin content or vice versa. Also digestibility and lignin degradation differed for each type of straw evaluated. BRM and LM showed a very strong negative correlation (correlation coefficient r= -98.54 and -98.07) with FXM (r = -92.43) being the next in line followed by FMS (r=-87.67) and BA (r=-87.39). PRM, MS and PS followed with JR (r= -66.54) at the end. High yield of LiP obtained through immobilization on PUF cubes was effective in delignification and could be employed for enhancing the digestibility of crop residues.