Expansin is a plant protein family that induces plant cell wall-loosening and cellulose disruption without exerting cellulose-hydrolytic activity. Expansin-like proteins have also been found in other eukaryotes such as nematodes and fungi. While searching for an expansin produced by bacteria, we found that the BsEXLX1 protein from Bacillus subtilis had a structure that was similar to that of a beta-expansin produced by maize. Therefore, we cloned the BsEXLX1 gene and expressed it in Escherichia coli to evaluate its function. When incubated with filter paper as a cellulose substrate, the recombinant protein exhibited both cellulose-binding and cellulose-weakening activities, which are known functions of plant expansins. In addition, evaluation of the enzymatic hydrolysis of filter paper revealed that the recombinant protein also displayed a significant synergism when mixed with cellulase. By comparing the activity of a mixture of cellulase and the bacterial expansin to the additive activity of the individual proteins, the synergistic activity was found to be as high as 240% when filter paper was incubated with cellulase and BsEXLX1, which was 5.7-fold greater than the activity of cellulase alone. However, this synergistic effect was observed when only a low dosage of cellulase was used. This is the first study to characterize the function of an expansin produced by a non-eukaryotic source.

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beta-Agarases are mostly categorized into three glycoside hydrolase (GH) families 16, 50, and 86. Recent genomic analysis of Saccharophagus degradans 2-40 revealed the presence of five agarase genes belonging to these GH families. Among the five agarases, Aga50D (a member of GH50) had neither been functionally characterized nor overexpressed. In this report, we present soluble overexpression and molecular characterization of Aga50D. Aga50D was expressed in an active form resulting in a single major product from agarose without intermediates. While known GH50 agarases have both endo-lytic and exo-lytic activities, which produce neoagarobiose as a final product through the intermediate, neoagaro-oligosaccharides, identification and analysis of the reaction product by mass spectrometry and 13C NMR showed that Aga50D had unique exo-lytic activity and was able to produce neoagarobiose directly from agarose. The optimum pH and temperature for the activity were 7.0 and 30 degrees C, respectively. The K (m) and V (max) for agarose were 41.9 mg/ml (4.2 mM) and 17.9 U/mg, respectively.

The importance of hens eggs as a source of specific antibodies (IgY) is well recognized. The protective effect of IgY obtained from hens immunized with Helicobacter pylori whole-cell lysate has been reported for the control of H. pylori infection. However, IgY produced by whole-cell lysates presents the possibility of cross-reactivity with other bacteria, including the normal human flora, and this could decrease the efficiency of IgY. In the present study, the immunodominant proteins of H. pylori with reactivity to H. pylori-specific IgY (IgY-Hp) were identified. IgY obtained from hens immunized with various fractions of H. pylori proteins was isolated and purified, titres of IgY-Hp against H. pylori were determined and cross-reactivity between IgY-Hp and normal human bacteria was examined by Western blot analysis. Finally, immunodominant H. pylori proteins were identified by LC/MS analysis. IgY obtained 2 months after immunization with H. pylori whole-cell lysate showed the highest antibody titre. Five immunodominant proteins were identified that were strongly reactive to IgY-Hp: urease â-subunit (62 kDa), heat-shock protein 60 (60 kDa), urease AE-subunit (26 kDa), probable peroxiredoxin (22 kDa) and probable thiol peroxidase (18 kDa). Immunization of hens with the immunodominant proteins identified would produce a more specific IgY against H. pylori.