TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation: (I) is produced by incubating the above mentioned host cell (claimed).Preferred Mixture: The industrial mixture further comprises a detergent.Preferred Fusion Protein: The heterologous peptide is a leucine zipper. WIDER DISCLOSURE - Also disclosed as new are the following:    (1) recombinant forms of (I);    (2) variants, and derivatives of (I);    (3) reagents, compositions, and methods that are useful for analysis of GuxA activity; and    (4) a polynucleotide encoding (I).    EXAMPLE - Molecular cloning of GuxA was as follows: Genomic DNA was isolated from Acidothermus cellulolyticus and purified. The purified genomic DNA was then digested and separated on agarose gels. DNA fragments in the range of 9-20 kilobase pairs were isolated from the gels. This purified genomic DNA was ligated into the BamH1 acceptor site of purified EMBL3 lambda phage arms. Phage DNA was packaged and plated with Escherichia coli LE392 in top agar which contained the soluble cellulose analog, and carboxymethylcellulose. The plates were then incubated overnight to allow transfection, bacterial growth, and plaque formation. Plates were stained followed by destaining. lambda plaques harboring endoglucanase clones showed up as unstained plaques. lambda clones which screened positive were purified. Individual phage isolates were named SL-1, SL-2, SL-3, and SL-4. Subsequent subcloning efforts employed the SL-3 clone which contained 14.2 kb fragment of A.cellulolyticus genomic DNA. Template DNA was constructed using a 9 kb BamH1 fragment obtained from 14.2 kb lambda clone SL3 prepared from A.cellulolyticus genomic DNA. The 9-kb BamHI fragment from SL3 was subcloned into pDR540 to generate a plasmid NREL501. NREL501 was first sequenced, then subcloned into pUC19, and transformed into E.coli XL1-blue for the production of template DNA for sequencing. Each subclone was sequenced, and the sequencing data from primer walking and subclones were assembled together to verify that all SL3 regions had been sequenced. An open reading frames (ORF) was found in the 9-kb BamHI fragment, C-terminal of E1, and then termed as GuxA. An ORF of 3687 bp defined in the specification and its deduced aa sequences having 1228 aas were obtained. The aa sequence predicted was determined to have significant homology to known cellulases.