**7. Cellulase**

**5. Phytase**

230 Enzyme Inhibitors and Activators

Phytases are enzymes that hydrolyze phytic acid which is an organic phosphorus source and makes inorganic usable phosphorus. Bacterially produced phytases are 3-phytase (EC 3.1.3.8), 4-phytase (EC 3.1.3.26) and protein-tyrosine-phosphatase (PTP, EC 3.1.3.48). Besides PTP, the other enzymes differentiate at which carbon they attack and take out the phosphorus in phytic acid. Several reports are available on the production of phytases. The organisms used are *Aerobacter aerogenes, B. amyloliquefaciens, B. subtilis, Enterobacter* sp., *E. coli, Klebsiella aerogenes, Lactobacillus amylovorus, Pseudomonas* sp., *Selenomonas ruminantium* [70] for three and four phytases and *B. subtilis, M. tuberculosis, S. aureus* [71–73]; typically grown under complex

media (tryptone, yeast extract and NaCl and sugars, for example, lactose as inducer)

700 [70] kDa, again depending on the producing host.

lysing the conversion of urea to carbon dioxide and ammonia:

These include Ba2+, Cd2+, Cu2+, Li+

(N H 2)<sup>2</sup>

phorodiamidate, H<sup>3</sup>

PO<sup>4</sup>

an activator compound [75]

**6. Urease**

The activity of bacterially produced phytases change with pH, ranging from 2 [74] to 10 [75], while the optimum pH range is narrower (from 2.7 [76] to 8.5 [77]). As for the temperature, optimum working range is between 20 [78] and 80°C [79] due to the presence of some thermophilic organisms [70, 79]. The molecular weight range is found to be between 12.8 [80] and

Similar to the other enzymes, several metal ions are reported to inhibit the phytase activity.

An important enzyme for plant nutrition, in particular for N-cycle is Urease (EC 3.5.1.5), cata-

 CO + H <sup>2</sup> O = C  O <sup>2</sup>

This enzyme is produced by bacteria, fungi as well as plants. Some bacterial producers are listed as *A. aerogenes, Arthrobacter oxydans, Bacillus pasteurii, Brevibacterium ammoniagenes, Brucella suis, E. coli, Helicobacter pylori, Proteus mirabilis, Providencia stuartii, S. ruminantium, Sporosarcina pasteurii, Staphylococcus saprophyticus* and *Ureaplasma urealyticum* [82–84], while the following organisms are reported to produce acid urease: *Arthrobacter mobilis, Lactobacillus fermentum* and *Streptococcus mitior* [82]. These are typically grown in batch mode, under complex (yeast extract, peptone and glucose) or chemically defined medium conditions, mezo-

The pH range whereby the enzyme works optimally is 2–9 [87–90], while optimum temperature ranges from 20 to 70°C [91–94]. Molecular weights can vary from 11.1 [82] to 600 [90] kDa. Listed inhibitors are methylurea, thiourea, acetohydroxamic acid, phenylphos-

N-Ethylmaleimide, 5,5′-Dithiobis (2-nitrobenzoic acid) (DNTB) [95]; 12-hydroxytetradecanoc acid, 3-hydroxytetradecanoc acid, 6-hydroxytetradecanoc acid [96, 97] and several metal ions [98, 99]. Glycerol, n-octylglucoside, polyethylene glycol (PEG), sodium dodecyl sulfate (SDS),

, 2-mercaptoethanol, boric acid, lodoacetamide, lodoacetic acid,

philic temperatures, with urea as the inducer of the enzyme production [85, 86].

, Mg2+, Mn2+and Zn2+ [77, 81], while EDTA is considered as

+ 2N H <sup>3</sup> (1)

Cellulase (EC 3.2.1.4) is an important enzyme, naturally produced by bacteria, fungi and protozoa, in particular by necrophilic microorganisms, and is responsible to hydrolyze (1-4)-beta-D-glucosidic linkages in cellulose, which is by far the most abundant organic compound, totalling to almost 50% of the biomass synthesised by photosynthetic fixation of CO2 . Cellulases also degrade cellulose available in lichenin and cereal beta-D-glucans. As such, it is a key enzyme in degradation of the most abundant polymer on earth. The bacterial producers are listed as *Acetivibrio cellulolyticus, B. Subtilis, B. Amyloliquefaciens, Cellulomonas fimi, Pseudomonas fluorescens, Ruminococcus albus, Thermobifida fusca, Thermotoga maritima* [102–104].

Ag+ , Hg2+, Mn2+, iodoacetamide, N-bromosuccinimide [105]; Cu2+, Pb2+, Fe2+, Sn2+, ethylenediaminetetraacetic acid (EDTA) [106]; NiCl2 , SrCl2 [7], sodium dodecyl sulphate (SDS) [107]; Cd2+, Co2+, Zn2+ [108] and 4-hydroxybenzoic acid, syringaldehyde, trans-cinnamic acid, vanillin [109] are shown to inhibit bacterial-originated cellulases. Arabitol, dithiothreitol, erythritol, glycerol, histamine [106]; N-ethylmaleimide [110]; CH3 COONa, NH4 Cl, NH4 NO3 [111] and Ca2+ [107] are shown that activate enzyme. For production of the cellulase enzyme, reported conditions are listed in **Table 2**.


\* Besides banana fruit stalk, wheat bran, rice bran and rice straw was tested as a substrate, but banana fruit stalk showed more cellulase activity. Also in this article with same media solid state and submerged fermentation was compared.

**Table 2.** Producing conditions of cellulase from bacteria.
