Microbial keratinases have become biotechnologically important since they target the hydrolysis of highly rigid, strongly cross-linked structural polypeptide "keratin" recalcitrant to the commonly known proteolytic enzymes trypsin, pepsin and papain. These enzymes are largely produced in the presence of keratinous substrates in the form of hair, feather, wool, nail, horn etc. during their degradation. The complex mechanism of keratinolysis involves cooperative action of sulfitolytic and proteolytic systems. Keratinases are robust enzymes with a wide temperature and pH activity range and are largely serine or metallo proteases. Sequence homologies of keratinases indicate their relatedness to subtilisin family of serine proteases. They stand out among proteases since they attack the keratin residues and hence find application in developing cost-effective feather by-products for feed and fertilizers. Their application can also be extended to detergent and leather industries where they serve as specialty enzymes. Besides, they also find application in wool and silk cleaning; in the leather industry, better dehairing potential of these enzymes has led to the development of greener hair-saving dehairing technology and personal care products. Further, their prospective application in the challenging field of prion degradation would revolutionize the protease world in the near future.

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Keratinolytic Bacillus licheniformis RG1 was used to study the mechanism of keratinolysis. Scanning electron microscopy studies revealed that bacterial cells grew closely adhered to the barbules of feathers, completely degrading them within 24 h. Biochemical studies indicated that the Bacillus strain produced an extracellular protease, which had keratinolytic potential. The extracellular keratinolytic activity (425 U) was synergistically enhanced by the addition of intracellular disulfide reductases (1712 U). However, these enzymes alone (keratinase and disulfide reductase), without live bacterial cells, failed to degrade the feather. Complete feather degradation was obtained only when living bacterial cells were present, emphasizing that bacterial adhesion plays a key role during the degradation process. The bacterial cells probably provide a continuous supply of reductant to break disulfide bridges. In addition, sulfite detected in the extracellular broth during feather degradation indicated that sulfitolysis may also play a role in feather degradation by the bacterium.

The present study aimed to determine the prebiotic effect of fruit and vegetable shots containing inulin derived from Jerusalem artichoke (JA). A three-arm parallel, placebo-controlled, double-blind study was carried out with sixty-six healthy human volunteers (thirty-three men and thirty-three women, age range: 18-50 years). Subjects were randomised into three groups (n 22) assigned to consume either the test shots, pear-carrot-sea buckthorn (PCS) or plum-pear-beetroot (PPB), containing JA inulin (5 g/d) or the placebo. Fluorescent in situ hybridisation was used to monitor populations of total bacteria, bacteroides, bifidobacteria, Clostridium perfringens/histolyticum subgroup, Eubacterium rectale/ Clostridium coccoides group, Lactobacillus/Enterococcus spp., Atopobium spp., Faecalibacterium prausnitzii and propionibacteria. Bifidobacteria levels were significantly higher on consumption of both the PCS and PPB shots (10·0 (SD 0·24) and 9·8 (SD 0·22) log 10 cells/g faeces, respectively) compared with placebo (9·3 (SD 0·42) log 10 cells/g faeces) (P, 0·0001). A small though significant increase in Lactobacillus/Enterococcus group was also observed for both the PCS and PPB shots (8·3 (SD 0·49) and 8·3 (SD 0·36) log 10 cells/g faeces, respectively) compared with placebo (8·1 (SD 0·37) log 10 cells/g faeces) (P¼ 0·042). Other bacterial groups and faecal SCFA concentrations remained unaffected. No extremities were seen in the adverse events, medication or bowel habits. A slight significant increase in flatulence was reported in the subjects consuming the PCS and PPB shots compared with placebo, but overall flatulence levels remained mild. A very high level of compliance (. 90 %) to the product was observed. The present study confirms the prebiotic efficacy of fruit and vegetable shots containing JA inulin.

Keratinases degrade feather in presence of a suitable reducing agent. Here we have demonstrated that conventional serine and cysteine proteases (subtilsin, chymotrypsin and papain) which selectively cleave proteins at the hydrophobic P1 residues also degrade feathers in presence of a suitable reducing agent in the form of live cells or chemical reductants. Further, trypsin and pepsin were also shown to degrade feather after cleaving hydrophobic residues of feathers following 2 h pre-treatment by any of the proteases.

The human gut microbiota comprises a diverse microbial consortium closely co-evolved with the human genome and diet. The importance of the gut microbiota in regulating human health and disease has however been largely overlooked due to the inaccessibility of the intestinal habitat, the complexity of the gut microbiota itself and the fact that many of its members resist cultivation and are in fact new to science. However, with the emergence of 16S rRNA molecular tools and "post-genomics" high resolution technologies for examining microorganisms as they occur in nature without the need for prior laboratory culture, this limited view of the gut microbiota is rapidly changing. This review will discuss the application of molecular microbiological tools to study the human gut microbiota in a culture independent manner. Genomics or metagenomics approaches have a tremendous capability to generate compositional data and to measure the metabolic potential encoded by the combined genomes of the gut microbiota. Another post-genomics approach, metabonomics, has the capacity to measure the metabolic kinetic or flux of metabolites through an ecosystem at a particular point in time or over a time course. Metabonomics thus derives data on the function of the gut microbiota in situ and how it responds to different environmental stimuli e.g. substrates like prebiotics, antibiotics and other drugs and in response to disease. Recently these two culture independent, high resolution approaches have been combined into a single "trans-genomic" approach which allows correlation of changes in metabolite profiles within human biofluids with microbiota compositional metagenomic data. Such approaches are providing novel insight into the composition, function and evolution of our gut microbiota.

This is the first report on beta-lactamases of Yersinia enterocolitica biovar 1A from Asia. Y. enterocolitica biovar 1A expressed both Bla-A and Bla-B. Heterogeneity was, however, discerned in the expression of Bla-A and by induction of Bla-B among clinical and non-clinical isolates of Y. enterocolitica biovar 1A.