Purification and properties of extracellular phytase from Bacillus sp. KHU-10

Characterization of a putative metal-dependent PTP-like phosphatase from Lactobacillus helveticus 2126

To date, there are very limited reports on sequence analysis and structure-based molecular modeling of phosphatases produced by probiotic bacteria. Therefore, a novel protein tyrosine-like phosphatase was characterized from L. helveticus 2126 in this study. The purified bacterial phosphatase was subjected to mass spectrometric analysis, and the identity of constructed sequence was analyzed using peptide mass fingerprint. The 3-D structure of protein was elucidated using homology modeling, while its stability was assessed using Ramachandran plot, VERIFY 3D, and PROCHECK. The bacterium produced an extracellular phosphatase of zone diameter 15 ± 0.8 mm on screening medium within 24 h of incubation. This bacterial phosphatase was highly specific towards sodium phytate as it yielded the lowest Km value of 299.50 ± 4.95 μM compared to other phosphorylated substrates. The activity was effectively stimulated in the presence of zinc, magnesium, and manganese ions thereby showing its PTP-like behavior. The phosphatase showed a molecular mass of 43 kDa, and the corresponding M/Z ratio data yielded 46% query coverage to Bacillus subtilis (3QY7). This showed a 61.1% sequence similarity to Ligilactobacillus ruminis (WP_046923835.1). The final sequence construct based on these bacteria showed a conserved motif "HCHILPGIDD" in their active site. In addition, homology modeling showed a distorted Tim barrel structure with a trinuclear metal center. The final model after energy minimization showed 90.9% of the residues in the favorable region of Ramachandran's plot. This structural information can be used in genetic engineering for improving the overall stability and catalytic efficiency of probiotic bacterial phosphatases.

Isolation and in-vitro characterization of extracellular phytase producing bacterial isolates for potential application in poultry feed

BACKGROUND

Phytase catalyses the breakdown of complex organic forms of phosphorous into simpler forms by sequential hydrolysis of phosphate ester bonds to liberate the inorganic phosphate. Supplementation of feeds with bacterial phytase therefore could enhance the bioavailability of phosphorus and micronutrients. Hence, the aim of this study was to isolate and characterize phytase producing bacteria from rhizosphere soil, fresh poultry excreta, and cattle shed to evaluate their potential in improving poultry feeds. Phytase producing bacteria were isolated using wheat bran extract medium.

RESULTS

A total of 169 bacterial isolates were purified and screened for phytase activity. Out of these, 36 were confirmed as positive for phytase enzyme activity. The bacterial isolates were identified by cultural, morphological, and biochemical features. The isolates were also identified by using 16 S rRNA gene sequencing. The bacterial isolates (RS1, RS8, RS10 and RS15) were provided with gene bank database accession numbers of MZ407562, MZ407563, MZ407564 and MZ407565 respectively. All isolates increased phytase production when cultured in wheat bran extract medium (pH 6) supplemented with 1% (wt/v) galactose and 1% (wt/v) ammonium sulphate incubated at 50oC for 72 h. Proximate composition analysis after supplementation of phytase showed that phytase supplementation improved bioavailability of phosphorus, calcium, potassium and sodium in poultry feed.

CONCLUSIONS

Overall, this study showed that the nutritional value of poultry feed can be improved using microbial phytase enzyme which reduces the cost of supplementation with inorganic phosphate.

Screening and characterization of Bacillus velezensis LB-Y-1 toward selection as a potential probiotic for poultry with multi-enzyme production property

Bacillus spp. have gained increasing recognition as an option to use as antimicrobial growth promoters, which are characterized by producing various enzymes and antimicrobial compounds. The present study was undertaken to screen and evaluate a Bacillus strain with the multi-enzyme production property for poultry production. LB-Y-1, screened from the intestines of healthy animals, was revealed to be a Bacillus velezensis by the morphological, biochemical, and molecular characterization. The strain was screened out by a specific screening program, possessed excellent multi-enzyme production potential, including protease, cellulase, and phytase. Moreover, the strain also exhibited amylolytic and lipolytic activity in vitro. The dietary LB-Y-1 supplementation improved growth performance and tibia mineralization in chicken broilers, and increased serum albumin and serum total protein at 21 days of age (p < 0.05). Besides, LB-Y-1 enhanced the activity of serum alkaline phosphatase and digestive enzyme in broilers at 21 and 42 days of age (p < 0.05). Analysis of intestinal microbiota showed that a higher community richness (Chao1 index) and diversity (Shannon index) in the LB-Y-1 supplemented compared with the CON group. PCoA analysis showed that the community composition and structure were distinctly different between the CON and LB-Y-1 group. The beneficial genera such as Parasutterella and Rikenellaceae were abundant, while the opportunistic pathogen such as Escherichia-Shigella were reduced in the LB-Y-1 supplemented group (p < 0.05). Collectively, LB-Y-1 can be considered as a potential strain for further utilization in direct-fed microbial or starter culture for fermentation.

Research status of Bacillus phytase

Phytic acid is abundant in seeds, roots and stems of plants, it acts as an anti-nutrient in food and feed industry, since it affects the absorption of nutrients by humans and monogastric animals. Furthermore, phosphorus produced through its decomposition by microorganisms can cause environmental pollution. Phytase degrades phytic acid generating precursors of inositol that can be used in clinical practice; in addition, phytase treatment can minimize the anti-nutritional effect of phytic acid. The use of phytase synthesized from Bacillus is more advantageous due to its high activity. Additionally, its good heat resistance under neutral conditions greatly fills the gap of commercial utilization of acid phytase. In this review, we summarize the latest research results on Bacillus phytase, including its physiological and biochemical characteristics, molecular structure information, calcium effects on its catalytic activity and stability, its catalytic mechanism and molecular modification.

Enhanced Phytase Production by Bacillus subtilis subsp. subtilis in Solid State Fermentation and its Utility in Improving Food Nutrition

BACKGROUND

Phytic acid acts as anti-nutritional factor in food and feed ingredients for monogastric animals as they lack phytases.

OBJECTIVE

Phytase production by Bacillus subtilis subsp. subtilis JJBS250 was studied in solid state fermentation and its applicability in dephytinization of food Methods: Bacterial culture was grown in solid state fermentation using wheat bran and various culture conditions were optimized using 'One variable at a time' (OVAT) approach. Effects of different substrates (wheat bran, wheat straw, sugarcane bagasse), incubation time (24, 48, 72 and 96 h), incubation temperatures (25, 30, 35 and 40 oC), pH (4.0, 5.0, 6.0, 7.0 and 8.0) and moisture content (1:1.5, 1:2.0, 1:2.5 and 1:3) were studied on phytase production. Bacterial phytase was used in dephytinization of food samples.

RESULTS

Optimization of phytase production was studied in solid state fermentation (SSF) using 'One variable at a time' (OVAT) approach. Bacillus subtilis subsp. subtilis JJBS250 grew well in various agroresidues in SSF and secreted high enzyme titres using wheat bran at 30 oC and pH 5.0 after incubation time of 48 h with substrate to moisture ratio of 1:3. Glucose and ammonium sulphate supplementation to wheat bran further enhanced phytase production in SSF. Optimization of phytase production resulted in 2.4-fold improvement in phytase production in solid state fermentation. The enzyme resulted in dephytinization of wheat and rice flours with concomitant release of inorganic phosphate, reducing sugar and soluble protein.

CONCLUSION

Optimization resulted in 2.34-fold enhancement in phytase production by bacterial culture that showed dephytinization of food ingredients with concomitant release of nutritional components. Therefore, phytase of B. subtilis subsp. subtilis JJBS250 could find application in improving nutritional quality of food and feed of monogastric animals.

Identification of two novel bacterial phosphatase-encoding genes in Pseudomonas putida strain P13

AIMS

Isolation and identification of genes encoding putative phosphatases from Pseudomonas putida strain P13 DSM 23335.

METHODS AND RESULTS

By functional screening of a P. putida P13 genomic library, a number of Pho⁺ clones were identified. Two genes were identified that encoded proteins exhibiting both phytase and sugar phosphatase activities. The proteins were 249 and 462 amino acids, with molecular masses of 26 and 50 kDa respectively. Sequence alignments revealed no significant similarities to representatives of known phosphatase or phytase gene families. However, the genes were found to have a high similarity to members of the major facilitator superfamily (MFS). Both genes were overexpressed in Escherichia coli and the corresponding partially purified recombinant enzymes were found to have significant phytate-dephosphorylating activity. The protein designated P. putida phytase 1 (Ppp1) displayed the highest activity among potential substrates studied on Na phytate, whereas Ppp2 more likely represents a sugar phosphatase than a phytase. The optimal conditions for phytate dephosphorylation were determined as 60°C and pH 4·5 (Ppp1) or pH 5·0 (Ppp2).

CONCLUSIONS

Two novel bacterial phosphatase-encoding genes, named ppp1 and ppp2, were isolated from P. putida P13 DSM 23335 by a functional screening procedure.

SIGNIFICANCE AND IMPACT OF THE STUDY

Phosphatase-encoding genes are of great importance for industrial applications, particularly in agriculture. The identified phosphatase genes represent a new class of acid phosphatases.

Production of biostimulants from okara through enzymatic hydrolysis and fermentation with Bacillus licheniformis: comparative effect on soil biological properties

In this work okara (OK), a by-product of soy milk manufacturing, is submitted to an enzymatic hydrolysis and a fermentative process to produce different soil biostimulants (BS): EH, hydrolysate obtained by the enzymatic process; FHEB, fermentation broth with Bacillus licheniformis and the enzymes secreted during the fermentation; FHE, fermentation broth without bacteria and FH, the FHE hydrolysate in which enzymes were denatured. Enzymatic hydrolysates showed a different chemical composition compared with fermented hydrolysates and OK. It had a higher protein concentration as well as C, P and K. The proteins of OK were converted into peptides with a lower molecular weight, the fermented hydrolysates being those with the lowest molecular weight profile. The influences of hydrolysates and OK were tested in soil, finding that β-glucosidase, phosphatase and dehydrogenase activities were stimulated by every treatment. However, it was observed that EH produced a greater stimulation of dehydrogenase and phosphatase than both OK and fermented BS. The bacterial and fungal phospholipid fatty acids were also higher in soils amended with BS than those of the control and soils with OK. It has also been found that β-glucosidase, phosphatase and microbial biomass were dose-dependent in every treatment, but dehydrogenase only was dose-dependent in EH and OK treatments.

Genetic transformation of tropical maize (Zea mays L.) inbred line with a phytase gene from Aspergillus niger

A full-length cDNA of phyA gene of Aspergillus niger, encoding phytase enzyme, was cloned and expressed in E. coli BL21 cells and assayed for its activity. The phyA cDNA consisted of 1404 bp, which encoded 467 amino acid residues. The phytase activity of purified phytase was 826.33 U/mL. The phyA gene under the control of endosperm-specific promoters was transformed into an Indian maize inbred line, UMI29, using particle bombardment-mediated transformation method to generate transgenic maize plants over-expressing phytase in seeds. PCR and GUS analyses demonstrated the presence of transgenes in T₀ transgenic plants and their stable inheritance in the T₁ progenies. Three transgenic events expressing detectable level of A. niger phytase were characterized by western blot analysis. Phytase activity of 463.158 U/kg of seed was observed in one of the events, JB-UMI29-Z17/2. The phytase activity of transgenic maize seeds was 5.5- to 7-fold higher than the wild-type UMI29 seeds and, consequently, the seeds had 0.6- to 5-fold higher inorganic phosphorus content.

Spectroscopic properties and molecular structure of copper phytate complexes: IR, Raman, UV-Vis, EPR studies and DFT calculations

The copper phytate IP6Cu, IP6Cu₂ and IP6Cu₃ complexes were synthesized changing the phytate to metal mole ratio. The obtained products have been characterized by means of chemical and spectroscopic studies. Spectroscopic ATR/IR, FT-Raman, UV–Vis, EPR and magnetic measurements were carried out. The structures of these compounds have been proposed on the basis of the group theory and geometry optimization taking into account the shape and number of the bands corresponding to the stretching and bending vibrations of the phosphate group and metal–oxygen polyhedron. The role of the inter- and intra-hydrogen bonds in stabilization of the structure has been discussed. EPR studies showed that a local rhombic symmetry of copper ions appears in the studied phytates. Dominant interactions show antiferromagnetic properties depending on the content of paramagnetic ions.

Interactive effects of phosphorus, calcium, and phytase supplements on products of phytate degradation in the digestive tract of broiler chickens

This study aimed to distinguish between the single and interactive effects of phosphorus (P), calcium (Ca), and phytase on products of phytate degradation, including the disappearance of myo-inositol (MI), P, Ca, and amino acids (AA) in different segments of the digestive tract in broiler chickens. Additionally, all dephosphorylation steps from myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP₆) to MI were investigated in the digesta of the terminal ileum. Unsexed Ross 308 broiler chickens were allocated to 56 pens with 19 birds per pen, and assigned to one of 8 dietary treatments. The dietary treatments included diets without (P−, 4.1 g/kg DM) or with (P+, 6.9 g/kg DM) monosodium phosphate supplementation, without (Ca−, 6.2 g/kg DM) or with (Ca+, 10.3 g/kg DM) additional fine limestone supplementation, and without or with 1,500 FTU phytase/kg feed in a factorial design. Adding Ca or P had no effect on InsP₆ disappearance in the crop when phytase was added. InsP₆ disappearance up to the terminal ileum (P−Ca− 56%) was decreased in P+Ca− (40%), and even more so in P+Ca+ (21%), when no phytase was added. Adding phytase removed all effects of P and Ca (77 to 87%); however, P+Ca+ increased the concentrations of lower InsP esters and reduced free MI in the ileum, even in the presence of phytase. These results indicate that mineral supplements, especially P and Ca combined, reduce the efficacy of endogenous microbial or epithelial phosphatases. Supplementation with phytase increased, while supplementation with Ca decreased the concentration of MI in all segments of the digestive tract and in blood plasma, demonstrating the ability of broilers to fully degrade phytate and absorb released MI. While AA disappearance was not affected by P or Ca, or an interaction among P, Ca, and phytase, it increased with the addition of phytase by 2 to 6%. This demonstrates the potential of the phytase used to increase AA digestibility, likely independent of P and Ca supply.

Effects of the inclusion of a Bacillus direct-fed microbial on performance parameters, bone quality, recovered gut microflora, and intestinal morphology in broilers consuming a grower diet containing corn distillers dried grains with solubles

Distillers dried grains with solubles (DDGS) have increasingly been used in poultry diets as a consequence of rising grain costs. Some, but not all, sources of DDGS have a variable compositional value, and a high inclusion of this by-product could be considered a risk factor for presentation of enteric diseases. Presently, 2 experiments were conducted using a starter corn-soybean diet (zero to 7 d) and a corn-DDGS-soybean grower diet (8 to 28 d) with or without inclusion of a Bacillus-direct-fed microbial (DFM). In both experiments, day-of-hatch chicks were randomly assigned to 2 different groups: control group without DFM or Bacillus-DFM group, containing 10⁶ spores/g of feed. In each experiment, 8 pens of 20 chicks (n = 160/group) were used. Performance parameters of BW, BW gain (BWG), feed intake (FI), and feed conversion (FCR) were evaluated in each growth phase. Additionally, in experiment 2, intestinal samples were collected to determine duodenal and ileal morphology (n = 8/group), as well as the microbiota population of total lactic acid bacteria (TLAB), total Gram-negative bacteria (TGNB), and total anaerobic bacteria (TAB) on d 28 (n = 16/group). Furthermore, both tibias were evaluated for bone strength and bone composition (n = 16/group). In both experiments BW, BWG, and FCR were improved by the DFM when compared to the control group (P < 0.05). In experiment 2, chickens supplemented with the DFM had less TGNB in the foregut intestinal segment and higher TLAB counts in both foregut and hindgut sections (P < 0.05). In addition significant increases in tibia breaking strength and bone mineralization were observed in the DFM group when compared with the control. In the case of intestinal morphology, DFM dietary inclusion increased villus height (VH), villus width, villus area, muscular thickness, and the VH to crypt depth ratio (VH:CD) in both duodenum and ileum sections. Results of the present study suggest that consumption of a selected Bacillus-DFM producing a variable set of enzymes could contribute to enhanced performance, intestinal microbial balance, and bone quality in broiler chickens consuming a grower diet that contains corn-DDGS.

Screening and Characterization of Phytases from Bacteria Isolated from Chilean Hydrothermal Environments

Phytases are enzymes involved in organic phosphorus cycling in nature and widely used as feed additives in animal diets. Thermal tolerance is a desired property of phytases. The objectives of this study were to screen and characterize bacterial phytases from Chilean hydrothermal environments. In this study, 60% (30 of 63) of screened thermophilic (60 °C) isolates showed phytase activity in crude protein extracts. The characterization of phytase from two selected isolates (9B and 15C) revealed that both isolates produce phytases with a pH optimum at 5.0. The temperature optimum for phytate dephosphorylation was determined to be 60 and 50 °C for the phytases from the isolates 9B and 15C, respectively. Interestingly, the phytase from the isolate 15C showed a residual activity of 46% after incubation at 90 °C for 20 min. The stepwise dephosphorylation of phytate by protein extracts of the isolates 9B and 15C was verified by HLPC analysis. Finally, the isolates 9B and 15C were identified by partial sequencing of the 16S rRNA gene as members of the genera Bacillus and Geobacillus, respectively.

β-Propeller phytases: Diversity, catalytic attributes, current developments and potential biotechnological applications

Phytases are phosphatases which stepwise remove phosphates from phytic acid or its salts. β-Propeller phytase (BPPhy) belongs to a special class of microbial phytases that is regarded as most diverse, isolated and characterized from different microbes, mainly from Bacillus spp. BPPhy class is unique for its Ca²⁺-dependent catalytic activity, strict substrate specificity, active at neutral to alkaline pH and high thermostability. Numerous sequence and structure based studies have revealed unique attributes and catalytic properties of this class, as compared to other classes of phytases. Recent studies including cloning and expression and genetic engineering approaches have led to improvements in BPPhy which provide an opportunity for extended utilization of this class of phytases in improving animal nutrition, human health, plant growth promotion, and environmental protection, etc. This review describes the sources and diversity of BPPhy genes, biochemical properties, Ca²⁺ dependence, current developments in structural elucidation, heterogeneous expression and catalytic improvements, and multifarious applications of BPPhy.

Evaluation and Selection of Bacillus Species Based on Enzyme Production, Antimicrobial Activity, and Biofilm Synthesis as Direct-Fed Microbial Candidates for Poultry

Social concern about misuse of antibiotics as growth promoters (AGP) and generation of multidrug-resistant bacteria have restricted the dietary inclusion of antibiotics in livestock feed in several countries. Direct-fed microbials (DFM) are one of the multiple alternatives commonly evaluated as substitutes of AGP. Sporeformer bacteria from the genus Bacillus have been extensively investigated because of their extraordinary properties to form highly resistant endospores, produce antimicrobial compounds, and synthesize different exogenous enzymes. The purpose of the present study was to evaluate and select Bacillus spp. from environmental and poultry sources as DFM candidates, considering their enzyme production profile, biofilm synthesis capacity, and pathogen-inhibition activity. Thirty-one Bacillus isolates were screened for in vitro relative enzyme activity of amylase, protease, lipase, and phytase using a selective media for each enzyme, with 3/31 strains selected as superior enzyme producers. These three isolates were identified as Bacillus subtilis (1/3), and Bacillus amyloliquefaciens (2/3), based on biochemical tests and 16S rRNA sequence analysis. For evaluation of biofilm synthesis, the generation of an adherent crystal violet-stained ring was determined in polypropylene tubes, resulting in 11/31 strains showing a strong biofilm formation. Moreover, all Bacillus strains were evaluated for growth inhibition activity against Salmonella enterica serovar Enteritidis (26/31), Escherichia coli (28/31), and Clostridioides difficile (29/31). Additionally, in previous in vitro and in vivo studies, these selected Bacillus strains have shown to be resistant to different biochemical conditions of the gastrointestinal tract of poultry. Results of the present study suggest that the selection and consumption of Bacillus-DFM, producing a variable set of enzymes and antimicrobial compounds, may contribute to enhanced performance through improving nutrient digestibility, reducing intestinal viscosity, maintaining a beneficial gut microbiota, and promoting healthy intestinal integrity in poultry.

Phytases from Enterobacter and Serratia species with desirable characteristics for food and feed applications

Phytases are enzymes of great industrial importance with wide range of applications in animal and human nutrition. These catalyze the hydrolysis of phosphomonoester bonds in phytate, thereby releasing lower forms of myo-inositol phosphates and inorganic phosphate. Addition of phytase to plant-based foods can improve its nutritional value and increase mineral bioavailability by decreasing nutritional effect of phytate. In the present investigation, 43 phytase positive bacteria on PSM plates were isolated from different sources and characterized for phytase activity. On the basis of phytase activity and zone of hydrolysis, two bacterial isolates (PSB-15 and PSB-45) were selected for further characterization studies, i.e., pH and temperature optima and stability, kinetic properties and effect of modulators. The phytases from both isolates were optimally active at the pH value from 3 to 8 and in the temperature range of 50-70 °C. Further, the stability of isolates was good in the pH range of 3.0-8.0. Much variation was observed in temperature and storage stability, responses of phytases to metal ions and modulators. The K m and V max values for PSB-15 phytase were 0.48 mM and 0.157 μM/min, while for PSB-45 these were 1.25 mM and 0.140 μM/min, respectively. Based on 16S rDNA gene sequence, the isolates were identified as Serratia sp. PSB-15 (GenBank Accession No. KR133277) and Enterobacter cloacae strain PSB-45 (GenBank Accession No. KR133282). The novel phytases from these isolates have multiple characteristics of high thermostability and good phytase activity at desirable range of pH and temperature for their efficient use in food and feed to facilitate hydrolysis of phytate-metal ion complex and in turn, increased bioavailability of important metal ions to monogastric animals.

Mining of Ruminant Microbial Phytase (RPHY1) from Metagenomic Data of Mehsani Buffalo Breed: Identification, Gene Cloning, and Characterization

Phytases have been widely used as animal feed supplements to increase the availability of digestible phosphorus, especially in monogastric animals fed cereal grains. The present study describes the identification of a full-length phytase gene of <i>Prevotella</i> species present in Mehsani buffalo rumen. The gene, designated as RPHY1, consists of 1,251 bp and is expressed into protein with 417 amino acids. A homology search of the deduced amino acid sequence of the RPHY1 phytase gene in a nonredundant protein database showed that it shares 92% similarity with the histidine acid phosphatase domain. Subsequently, the RPHY1 gene was expressed using a pET32a expression vector in <i>Escherichia coli </i>BL21 and purified using a His60 Ni-NTA gravity column. The mass of the purified RPHY1 was estimated to be approximately 63 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimal RPHY1 enzyme activity was observed at 55°C (pH 5) and exhibited good stability at 5°C and within the acidic pH range. Significant inhibition of RPHY1 activity was observed for Mg²⁺ and K⁺ metal ions, while Ca²⁺, Mn²⁺, and Na⁺ slightly inhibited enzyme activity. The RPHY1 phytase was susceptible to SDS, and it was highly stimulated in the presence of EDTA. Overall, the observed comparatively high enzyme activity levels and characteristics of the RPHY1 gene mined from rumen prove its promising candidature as a feed supplement enzyme in animal farming.

A novel phytase characterized by thermostability and high pH tolerance from rice phyllosphere isolated Bacillus subtilis B.S.46

In this study, an extracellular alkali-thermostable phytase producing bacteria, Bacillus subtilis B.S.46, were isolated and molecularly identified using 16S rRNA sequencing. Response surface methodology was applied to study the interaction effects of assay conditions to obtain optimum value for maximizing phytase activity. The optimization resulted in 137% (4.627 U/mL) increase in phytase activity under optimum condition (56.5 °C, pH 7.30 and 2.05 mM sodium phytate). The enzyme also showed 60-73% of maximum activity at wide ranges of temperature (47-68 °C), pH (6.3-8.0) and phytate concentration (1.40-2.50 mM). The partially purified phytase demonstrated high stability over a wide range of pH (6.0-10.0) after 24 h, retaining 85% of its initial activity at pH 6 and even interestingly, the phytase activity enhanced at pH 8.0-10.0. It also exhibited thermostability, retaining about 60% of its original activity after 2 h at 60 °C. Cations such as Ca(2+) and Li(+) enhanced the phytase activity by 10-46% at 1 mM concentration. The phytase activity was completely inhibited by Cu(2+), Mg(2+), Fe(2+), Zn(2+), Hg(2+) and Mn(2+) and the inhibition was in a dose dependent manner. B. subtilis B.S.46 phytase had interesting characteristics to be considered as animal feed additive, dephytinization of food ingredients, and bioremediation of phosphorous pollution in the environment.

Bacillus phytases: Current status and future prospects

Phytases catalyze the hydrolysis of phytic acid in a stepwise manner to lower inositol phosphates, myo-inositol (having important role in metabolism and signal transduction pathways), and inorganic phosphate. These enzymes have been widely used in animal feed in order to improve phosphorus nutrition and to decrease pollution in animal waste. Compared to previously described phytases, the phytase (PhyL) from Bacillus licheniformis ATCC 14580 has attractive biochemical properties which can increase the profitability of several biotechnological procedures (animal nutrition, humain health…etc). Due to its amino acid sequence with critical substitutions, the PhyL could be a model to enhance other phytases features, in terms of thermal stability and high activity. Otherwise, an engineered PhyL, with low pH optimum, will represent a challenge within the class of β- propeller phytases.

Isolation and molecular characterization of thermostable phytase from Bacillus subtilis (BSPhyARRMK33)

The thermostable phytase gene was isolated from Bacillus subtilis ARRMK33 (BsPhyARRMK33). The gene has an ORF of 1152 bp and that encodes a protein of 383 amino acids. Sequence analysis showed high homology with Bacillus sp. phytase proteins, but no similarity was found with other phytases. SDS-PAGE analysis exhibited a predicted molecular mass of 42 kDa. Homology modeling of BsPhyARRMK33 protein based on Bacillus amyloliquefaciens crystal structure disclosed its β-propeller structure. BsPhyARRMK33 recombinant plasmid in pET-28a(+) was expressed in Rosetta gami B DE3 cells and the maximum phytase activity 15.3 U mg(-1) obtained. The enzyme exhibits high thermostability at various temperatures and broad pH ranges. The recombinant protein retained 74% of its original activity after incubation at 95 °C for 10 min. In the presence of Ca(2+), the recombinant phytase activity was maximal where as it was inhibited by EDTA. The optimal pH and temperature for the recombinant phytase activity is achieved at 7.0 and 55 °C, respectively. Thermostable nature and wide range of pH are promising features of recombinant BsPhyARRMK33 protein that may be employed as an efficient alternative to commercially known phytases and thereby alleviate environmental eutrophication.

Metabolite changes during natural and lactic acid bacteria fermentations in pastes of soybeans and soybean-maize blends

The effect of natural and lactic acid bacteria (LAB) fermentation processes on metabolite changes in pastes of soybeans and soybean-maize blends was studied. Pastes composed of 100% soybeans, 90% soybeans and 10% maize, and 75% soybeans and 25% maize were naturally fermented (NFP), and were fermented by lactic acid bacteria (LFP). LAB fermentation processes were facilitated through back-slopping using a traditional fermented gruel, thobwa as an inoculum. Naturally fermented pastes were designated 100S, 90S, and 75S, while LFP were designated 100SBS, 90SBS, and 75SBS. All samples, except 75SBS, showed highest increase in soluble protein content at 48 h and this was highest in 100S (49%) followed by 90SBS (15%), while increases in 100SBS, 90S, and 75S were about 12%. Significant (P < 0.05) increases in total amino acids throughout fermentation were attributed to cysteine in 100S and 90S; and methionine in 100S and 90SBS. A 3.2% increase in sum of total amino acids was observed in 75SBS at 72 h, while decreases up to 7.4% in 100SBS at 48 and 72 h, 6.8% in 100S at 48 h and 4.7% in 75S at 72 h were observed. Increases in free amino acids throughout fermentation were observed in glutamate (NFP and 75SBS), GABA and alanine (LFP). Lactic acid was 2.5- to 3.5-fold higher in LFP than in NFP, and other organic acids detected were acetate and succinate. Maltose levels were the highest among the reducing sugars and were two to four times higher in LFP than in NFP at the beginning of the fermentation, but at 72 h, only fructose levels were significantly (P < 0.05) higher in LFP than in NFP. Enzyme activities were higher in LFP at 0 h, but at 72 h, the enzyme activities were higher in NFP. Both fermentation processes improved nutritional quality through increased protein and amino acid solubility and degradation of phytic acid (85% in NFP and 49% in LFP by 72 h).

Coexpression and secretion of endoglucanase and phytase genes in Lactobacillus reuteri

A multifunctional transgenic Lactobacillus with probiotic characteristics and an ability to degrade β-glucan and phytic acid (phytate) was engineered to improve nutrient utilization, increase production performance and decrease digestive diseases in broiler chickens. The Bacillus subtilis WL001 endoglucanase gene (celW) and Aspergillus fumigatus WL002 phytase gene (phyW) mature peptide (phyWM) were cloned into an expression vector with the lactate dehydrogenase promoter of Lactobacillus casei and the secretion signal peptide of the Lactococcus lactisusp45 gene. This construct was then transformed into Lactobacillus reuteri XC1 that had been isolated from the gastrointestinal tract of broilers. Heterologous enzyme production and feed effectiveness of this genetically modified L. reuteri strain were investigated and evaluated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that the molecular mass of phyWM and celW was approximately 48.2 and 55 kDa, respectively, consistent with their predicted molecular weights. Endoglucanase and phytase activities in the extracellular fraction of the transformed L. reuteri culture were 0.68 and 0.42 U/mL, respectively. Transformed L. reuteri improved the feed conversion ratio of broilers from 21 to 42 days of age and over the whole feeding period. However, there was no effect on body weight gain and feed intake of chicks. Transformed L. reuteri supplementation improved levels of ash, calcium and phosphorus in tibiae at day 21 and of phosphorus at day 42. In addition, populations of Escherichia coli, Veillonella spp. and Bacteroides vulgatus were decreased, while populations of Bifidobacterium genus and Lactobacillus spp. were increased in the cecum at day 21.

[Isolation and characterisation of a new bacillar phytase]

Bacillus ginsengihumi phytase has been firstly isolated and studied from the recombinant Escherichia coli strain cellular lysates. The enzyme was obtained from the cellular lysate, purified till homogeneous condition, primary structure was determined. It's concluded that phytase relates to beta-propeller class of phosphatases. The molecular weight of the protein was 41 kDa, pI was 4.8. Some physical and chemical properties of the enzyme were studied.

Thermostable Alkaline Phytase from Alcaligenes sp. in Improving Bioavailability of Phosphorus in Animal Feed: In Vitro Analysis

A bacterial isolate, Alcaligenes sp. secreting phytase (EC 3.1.3.8), was isolated and characterized. The optimum conditions for the production of phytase included a fermentation period of 96 h, pH 8.0, and the addition of 1% (w/v) maltose and 1% (w/v) beef extract to the culture medium. This enzyme was purified to homogeneity and had an apparent molecular mass of 41 kDa. The optimum pH range and temperature for the activity of phytase were found to be 7.0-8.0 and 60°C, respectively. This enzyme was strongly inhibited by 0.005 M of Mn²⁺, Mg²⁺, and Zn²⁺. In vitro studies revealed that the phytase from Alcaligenes sp. released inorganic phosphate from plant phytates. Phytase released 1930 ± 28, 1740 ± 13, 1050 ± 31, 845 ± 7, 1935 ± 32, and 1655 ± 21 mg inorganic phosphate/kg plant phytates, namely, chick pea, corn, green pea, groundnut, pearl pea, and chick feed, respectively.

Isolation and identification of phytate-degrading rhizobacteria with activity of improving growth of poplar and Masson pine

A number of soil microorganisms can convert insoluble forms of phosphorus (P) to an accessible form to increase plant yields. Phytate is such a large kind of insoluble organic phosphorus that plants cannot absorb directly in soil, so the objectives of this study were to isolate, screen phytate-degrading rhizobacteria (PDRB), and to select potential microbial inocula that could increase the P uptake by plants. In this study, a total of 24 soil samples were collected from natural habitats of eight poplar and pine planting areas from the eastern to southern China. 17 PDRB strains were preliminarily screened from the rhizosphere soil of poplars and pines by the visible decolorization in the phytate selective medium. The highest ratio of the total diameter (colony + halo zone) to the colony diameter of the isolates was JZ-GX1, 3.85. Afterward, 17 PDRB strains were further determined for their abilities to degrade sodium phytate based on the amount of liberated inorganic P in liquid phytate specific medium. The results showed that the phytase ability of the three highest PDRB strains: JZ-GX1, JZ-DZ1 and JZ-ZJ1 were up to 2.58, 2.36 and 2.24 U/mL, respectively, much better than most of the bacteria reported in previous studies. In the soil-plant experiment, compared to CK, the best three strains of PDRB all could significantly promote growth of poplar and Masson pine under container growing. The three efficient PDRB strains were identified as follow: JZ-GX1, Rahnella aquatilis, both JZ-DZ1 and JZ-ZJ1 being autofluorescent, Pseudomonas fluorescens, by 16S rDNA gene sequencing technology, Biolog Identification System and biological characterization. The present study suggests that the three screened PDRB strains would have great potential application as biological fertilizers in the future.

Purification and characterization of a novel acid phosphatase from the split gill mushroom Schizophyllum commune

A monomeric acid phosphatase (ACP) with a molecular mass of 72.5 kDa was purified from fresh fruiting bodies of cultured Schizophyllum commune mushroom. The isolation procedure entailed ion exchange chromatography on DEAE-cellulose, CM-cellulose, and Q-sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. It demonstrated a unique N-terminal amino acid sequence of NAPWAQIDEV, which exhibited 60% amino acid identity to that of S. commune hypothetical histidine ACP based on its genome sequence, but less than 30% amino acid identity to that of other fungal ACPs previously reported. The ACP exhibited an optimum temperature at 50 °C, an optimum pH at pH 4.6, and was considerably stable at a pH range of 4.0 to 9.0, and a temperature range of 20-40 °C. The Km of the purified enzyme for ρ-nitrophenyl phosphate (ρNPP) was 0.248 mM and the Vmax was 9.093 × 10(-3)  μM/min. ACP activity was strongly inhibited by Al(3+) and Fe(3+) , but enhanced by Co(2+) , Mg(2+) , and Ca(2+) at a concentration of 0.5 mM.

Degradation of Phytate Pentamagnesium Salt by Bacillus sp. T4 Phytase as a Potential Eco-friendly Feed Additive

A bacterial isolate derived from soil samples near a cattle farm was found to display extracellular phytase activity. Based on 16S rRNA sequence analysis, the strain was named Bacillus sp. T4. The optimum temperature for the phytase activity toward magnesium phytate (Mg-InsP₆) was 40°C without 5 mM Ca²⁺ and 50°C with 5 mM Ca²⁺. T4 phytase had a characteristic bi-hump two pH optima of 6.0 to 6.5 and 7.4 for Mg-InsP₆. The enzyme showed higher specificity for Mg-InsP₆ than sodium phytate (Na-InsP₆). Its activity was fairly inhibited by EDTA, Cu²⁺, Mn²⁺, Co²⁺, Ba²⁺ and Zn²⁺. T4 phytase may have great potential for use as an eco-friendly feed additive to enhance the nutritive quality of phytate and reduce phosphorus pollution.