Table 3 Keyword clusters analysis of scientific publication of thermostable enzymes in the Scopus collection database (1976–2022)

1

Amylase, bacillus, bacteria, bacterial enzymes, bacterial strains, bacterium, beta glucosidase, biocatalyst, biofuel, biomass, biosynthesis, biotechnology, cellulase, cellulose, enzyme assay, enzyme immobilization, enzyme synthesis, fermentation, fungi, genetic engineering, geobacillus, geobacillus stearotherm, glucose, hydrolysis, microbiology, phylogeny, starch, thermodynamic stability, thermophile, thermophilic bacteria, thermostability, thermostable enzyme, triacylglycerol lipase, xylan endo 1,3 beta xyloses

2

Bacterial protein, biocatalysis, catalysis, catalytic domain, chemistry, crystal structure, x-ray crystallography, enzyme active site, enzyme structure, enzymology, glycosidase, glycoside hydrolases, mutagenesis, protein confirmation, protein denaturation, protein engineering, protein stability

3

Amino acid, archeal proteins, cloning, molecular DNA, Escherichia coli, gene expression, gene sequence, hydrogen-ion concentration, isolation and purification, molecular cloning, molecular genetics, nucleotide sequences, polymerase chain reaction, protein expression, protein purification, recombinant protein, sequence alignment, sequence homology, thermotoga maritima, thermus, thermus thermophilus

4

Bacterial enzymes, enzyme analysis, enzymes inhibition, enzymes kinetics, enzyme purification, enzyme specificity, enzyme substrate, substrate specificity, substrates

5

Thermotoga maritama