Purification and characterization of chitinase A of Streptomyces cyaneus SP-27: an enzyme participates in protoplast formation from Schizophyllum commune mycelia.

A culture filtrate of Bacillus circulans KA-304 grown on a cell-wall preparation of Schizophyllum commune has an activity to form protoplasts from S. commune mycelia. alpha-1,3-Glucanase and chitinase I, which were isolated from the filtrate, did not form the protoplast by itself while a mixture of them showed protoplast-forming activity. Streptomyces cyaneus SP-27 was isolated based on the productivity of chitinase. The culture filtrate of S. cyaneus SP-27 did not form S. commune protoplasts, but addition of it to alpha-1,3-glucanase of B. circulans KA-304 brought about protoplast-forming activity. Chitinase A isolated from the S. cyaneus SP-27 culture filtrate was more effective than chitinase I of B. circulans KA-304 for the protoplast formation in combination with alpha-1,3-glucanase. The N-terminal amino acid sequence of chitinase A (MW 29,000) has a sequential similarity to those of several Streptomycete family 19 chitinases. Chitinase A adsorbed to chitinous substrate and inhibited the growth of Trichoderma reesei mycelia. Anomer analysis of the reaction products also suggested that the enzyme is a family 19 chitinase.

Cloning and expression of chitinase A gene from Streptomyces cyaneus SP-27: the enzyme participates in protoplast formation of Schizophyllum commune.

Chitinase A of Streptomyces cyaneus SP-27 or chitinase I of Bacillus circulans KA-304 showed the protoplast-forming activity when combined with alpha-1,3-glucanase of B. circulans KA-304. The gene of chitinase A was cloned. It consisted of 903 nucleotides encoding 301 amino acid residues, including a putative signal peptide (35 amino acid residues). The deduced N-terminal moiety of chitinase A showed sequence homology with the chitin-binding domain of chitinase F from Streptomyces coelicolor and chitinase 30 from Streptomyces olivaceoviridisis. The C-terminal moiety also showed high sequence similarity to the catalytic domain of several Streptomyces family 19 chitinases as well as that of chitinase I of B. circulans KA-304. Recombinant chitinase A was expressed in Escherichia coli Rosetta-gami B (DE 3). The properties of the recombinant enzyme were almost the same as those of chitinase A purified from a culture filtrate of S. cyaneus SP-27. The recombinant enzyme was superior to B. circulans KA-304 chitinase I not only in respect to protoplast forming activity in a mixture containing alpha-1,3-glucanase, but also to antifungal activity and powder chitin-hydrolyzing activity.

Purification of Aspergillus sp. S1-13 chitinases and their role in saccharification of chitin in mash of solid-state culture with shellfish waste.

In a suspension of solid-state culture of Aspergillus sp. S1-13 containing a lactic acid-treated crab shell as the substrate, the saccharification of chitin in the shell proceeded to form N-acetylglucosamine (GlcNAc): the culture was the source of chitin and chitinases. The analysis of chitinases in the water-extract of the solid-state culture indicated occurrence of an exochitinase (Exo, MW 73 kDa) and two endochitinases. The amounts of the endochitinases suggested that one of them (Endo-1, MW 45 kDa) might be the main species in the chitin-saccharification. The amount of GlcNAc released from the LA-treated crab shell by the combined action of isolated Exo and Endo-1 was very small, predicting participation in the saccharification of other enzyme species, which might be hardly extracted with water from the solid-state culture. The re-extraction of the solid-state culture using 2 M KCl, which was extracted with water beforehand, demonstrated another endochitinase (Endo-2, MW 51 kDa). Endo-2 isolated from the salt-extract can adsorb to chitin, and can hydrolyze the chitin in the adsorbed state. The roles of these chitinases in the chitin-saccharification based on their properties and combined action were discussed.

Utilization of shrimp shellfish waste as a substrate for solid-state cultivation of Aspergillus sp. S1-13: evaluation of a culture based on chitinase formation which is necessary for chitin-assimilation.

The utilization of shrimp shellfish waste as a substrate for solid-state cultivation of a filamentous fungus, Aspergillus sp. S1-13, was investigated. The organism was selected from among 220 isolates based on the productivity of its chitinolytic enzyme (chitinase), which might reflect microbial growth. The enzyme was produced only when the organism was grown on medium containing the shellfish waste. The addition of 58-65% water (w/w) to the medium was effective in enhancing production, and a certain amount of enzyme was observed in media of higher water content (up to about 75%). The initial pH and nitrogen source (ammonium sulfate) of the solid-state medium also affected the amount of enzyme. The amount of enzyme increased 2-fold in an optimum solid-state medium: 5 g of shrimp shellfish waste and 3 ml of basal medium (pH 5) containing 0.1% (NH4)2SO4 was inoculated with 4 ml of spore suspension; static cultivation at room temperature. The amount increased further (1.5-fold) when the cultivation was carried out at 37 degrees C, with 1.85 units of the enzyme formed from 1 g of shrimp shellfish waste. An analysis by ion-exchange column chromatography suggested the presence of at least two colloidal chitin-hydrolyzing enzymes and one p-nitrophenyl beta-D-N-acetylglucosaminide-hydrolyzing enzyme in an extract of the solid-state culture. The elution profile was similar to that obtained with a liquid culture filtrate.

Saccharification of chitin using solid-state culture of Aspergillus sp. S1-13 with shellfish waste as a substrate.

Saccharification of chitin was performed in a suspension (mash) of a solid-state culture of chitinase-producing Aspergillus sp. Sl-13 with acid-treated shellfish waste as a substrate. The conditions for the saccharifying reaction and the solid-state cultivation were examined from the viewpoint of saccharification in the mash. Optimum cultivation conditions were defined: a solid-state medium consisting of 5 g of 10% lactic acid-treated crab shells (0.50-2.36 mm in size) and 3 ml of a basal medium (0.028% KH2PO4 0.007% CaCl2.2H2O, and 0.025% MgSO4.7H2O) supplemented with 0.3% peptone was inoculated with 4 ml of spore suspension (1 x 10(7) spores/ml), and the water content of the medium was adjusted to 75%; static cultivation at 37 degrees C for 7 d. When a culture obtained under the optimum conditions was suspended in 70 ml of 50 mM sodium phosphate-citrate buffer (pH 4.0) and incubated at 45 degrees C for 11-13 d, 55 mM N-acetylglucosamine (GlcNAc) was formed in the solid-state culture mash, indicating that at least 33% of the initial chitin in the solid material was hydrolyzed. Through the experiments, the amounts of G1cNAc formed in the solid-state culture mash varied in a way similar to that of the water-extractable pnitrophenyl beta-D-N-acetylglucosaminide-hydrolyzing enzyme in the culture, but not to that of the colloidal chitin-hydrolyzing enzyme. G1cNAc-assimilating lactic acid bacteria, which were inoculated into the mash after or at the start of the saccharification, formed lactic acid with decreasing GlcNAc.

Cloning and expression of a Bacillus circulans KA-304 gene encoding chitinase I, which participates in protoplast formation of Schizophyllum commune.

KA-prep, a culture filtrate of Bacillus circulans KA-304 grown on a cell-wall preparation of Schizophyllum commune, has an activity to form protoplasts from S. commune mycelia, and a combination of alpha-1,3-glucanase and chitinase I, isolated from KA-prep, brings about the protoplast-forming activity. The gene of chitinase I was cloned from B. circulans KA-304 into pGEM-T Easy vector. The gene consists of 1,239 nucleotides, which encodes 413 amino acids including a putative signal peptide (24 amino acid residues). The molecular weight of 40,510, calculated depending on the open reading frame without the putative signal peptide, coincided with the apparent molecular weight of 41,000 of purified chitinase I estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The C-terminal domain of the deduced amino acid sequence showed high similarity to that of family 19 chitinases of actinomycetes and other organisms, indicating that chitinase I is the first example of family 19 chitinase in Bacillus species. Recombinant chitinase I without the putative signal peptide was expressed in Escherichia coli Rosetta-gami B (DE 3). The properties of the purified recombinant enzyme were almost the same as those of chitinase I purified from KA-prep, and showed the protoplast-forming activity when it was combined with alpha-1,3-glucanase from KA-prep. Recombinant chitinase I as well as the native enzyme inhibited hyphal extension of Trichoderma reesei.

A chitinase indispensable for formation of protoplast of Schizophyllum commune in basidiomycete-lytic enzyme preparation produced by Bacillus circulans KA-304.

KA-prep, a culture filtrate of Bacillus circulans KA-304 grown on a cell-wall preparation of Schizophyllum commune, has an activity to form protoplasts from S. commune mycelia. alpha-1,3-Glucanase, which was isolated from an ammonium sulfate fraction of 0-30% saturation of KA-prep, gave the protoplast-forming activity to an ammonium sulfate fraction of 30-50% saturation of KA-prep, which contained chitinase(s) and beta-glucanase(s) but was inactive in the protoplast formation. Chitinase(s) and beta-glucanase(s) in the ammonium sulfate fraction of 30-50% saturation were separated by DEAE-cellulofine A-500 column chromatography, and the protoplast-forming activity appeared when the chitinase preparation was mixed with the alpha-1,3-glucanase. The beta-glucanase preparation was not effective for the protoplast formation whereas its addition enhanced the protoplast-forming activity of the mixture of alpha-1,3-glucanase and the chitinase preparation. The chitinase preparation contained two chitinases (chitinase I and II). Chitinase I showed the protoplast-forming activity with alpha-1,3-glucanase, but chitinase II did not. Chitinase I, a monomeric protein with a molecular weight of 41,000, was active toward colloidal chitin and ethylene glycol chitin. Chitinase I produced predominantly N,N'-diacetylchitobiose and N,N',N"-triacetylchitotriose from colloidal chitin, and the enzyme was inactive to p-NP-beta-D-N-acetylglucosaminide, suggesting that it was an endo-type enzyme. The N-terminal amino acid sequence of chitinase I (A L A T P T L N V S A S S G M) had no sequential identity to those of known chitinases.