Amino acid and mineral digestibility,bone ash,and plasma inositol is increased by including microbial phytase in diets for growing pigs

Background The effect of microbial phytase on amino acid and energy digestibility is not consistent in pigs,which may be related to the phytase dosage or the adaptation length to the diet.Therefore,an experiment was conducted to test the hypotheses that increasing dietary phytase after an 18-day adaptation period:1)increases nutrient and energy digestibility;2)increases plasma P,plasma inositol,and bone ash of young pigs;and 3)demonstrates that maximum phytate degradation requires more phytase than maximum P digestibility.Results Data indicated that increasing inclusion of phytase[0,250,500,1,000,2,000,and 4,000 phytase units(FTU)/kg feed]in corn-soybean meal-based diets increased apparent ileal digestibility(AID)of Trp(quadratic;P<0.05),and of Lys and Thr(linear;P<0.05),and tended to increase AID of Met(linear;P<0.10).Increasing dietary phytase also increased AID and apparent total tract digestibility(ATTD)of Ca and P(quadratic;P<0.05)and increased ATTD of K and Na(linear;P<0.05),but phytase did not influence the ATTD of Mg or gross energy.Concentrations of plasma P and bone ash increased(quadratic;P<0.05),and plasma inositol also increased(linear;P<0.05)with increasing inclusion of phytase.Reduced concentrations of inositol phosphate(IP)6 and IP5(quadratic;P<0.05),reduced IP4 and IP3(linear;P<0.05),but increased inositol concentrations(linear;P<0.05)were observed in ileal digesta as dietary phytase increased.The ATTD of P was maximized if at least 1,200 FTU/kg were used,whereas more than 4,000 FTU/kg were needed to maximize inositol release.Conclusions Increasing dietary levels of phytase after an 18-day adaptation period increased phytate and IP ester degradation and inositol release in the small intestine.Consequently,increasing dietary phytase resulted in improved digestibility of Ca,P,K,Na,and the first 4 limiting amino acids,and in increased concentrations of bone ash and plasma P and inositol.In a corn-soybean meal diet,maximum inositol release requires approximately 3,200 FTU/kg more phytase than that required for maximum P digestibility.

植酸酶基因在嗜酸乳杆菌中的表达

植酸酶和嗜酸乳杆菌是重要的饲料添加剂,为获得产植酸酶的嗜酸乳杆菌菌株,克隆了大肠杆菌植酸酶基因,构建表达载体并转化嗜酸乳杆菌,对重组嗜酸乳杆菌进行发酵产酶并测定所产酶液的酶学性质,进一步研究重组嗜酸乳杆菌的耐酸性及植酸酶液的抗蛋白酶活性。结果表明:重组嗜酸乳杆菌发酵24 h植酸酶活性为984 U/mL,植酸酶的最适催化pH为4.5,最适催化温度为60℃。重组嗜酸乳杆菌在pH 2.0~4.5有一定的耐酸性,在pH 2.0条件下2 h的存活率为76.4%。植酸酶液用胃蛋白酶处理160 min后植酸酶液剩余85%的相对酶活,用胰蛋白酶处理160 min后剩余29%的相对酶活。上述研究结果为重组嗜酸乳杆菌后续应用研究提供了重要依据。

双功能域β-折叠桶植酸酶提高土壤有效磷含量研究

农业生产中过度使用无机磷肥引发了土壤板结等一系列问题,因此有必要寻找一种替代的可持续的磷肥来源。土壤有机磷主要以植酸的形式存在,植物不能直接吸收和利用。植酸水解释放植酸磷可提供一个生态友好型的解决方案。通过向土壤中添加来自Bacillus sp.HJB17的双功能域β-折叠桶植酸酶(phyHT),研究其在土壤中的稳定性,探究phyHT提高土壤有效磷含量、改善土壤理化性质以及促进植物生长的作用效果。结果显示,在湿润土壤中,土壤微生物对phyHT影响很小,phyHT可在较宽的温度(20~40℃)和pH值(6.0~9.0)范围内稳定存在12 h并发挥高效催化功能。外源性添加phyHT后:(1)土壤植酸含量减少了17.00%,有效磷含量增加了22.52%;(2)土壤pH下降,电导率上升,CaCO_(3)含量降低了3.55个百分点,土壤有机质、铵态氮和速效钾含量分别增加了10.54%、18.38%和27.49%;(3)小麦幼苗生长长度、干物质积累量以及芽、根部组织全磷含量均显著增加。因此,外源性添加phyHT能够促进土壤植酸水解,增加土壤有效磷含量,提高土壤磷素有效性,同时,在一定程度上改善土壤理化性质,促进植物生长。

L-肉碱、纤维素酶和植酸酶组合效应对肉鸡营养物质表观代谢率和体沉积率的影响

试验旨在探究饲料中添加L-肉碱、纤维素酶和植酸酶组合效应对肉鸡营养利用率和体沉积率的影响。试验采用L9(34)正交试验设计,将270只1日龄AA肉鸡随机分为9组,每组3个重复,每个重复10只鸡,试验期7周。在玉米-豆粕日粮基础上添加L-肉碱(25、50、75 mg/kg)、纤维素酶(500、1 000、2000mg/kg)与植酸酶(150、250、350mg/kg)。结果表明:当3种饲料添加剂的组合为75mg/kg肉碱、1 000 mg/kg纤维素酶、150 mg/kg植酸酶时,能够提高肉鸡粗蛋白质(CP)、粗脂肪(EE)、钙(Ca)和磷(P)的代谢率,其中植酸酶是影响CP和P代谢率的主效因子,L-肉碱是影响EE和Ca代谢率的主效因子;当3种饲料添加剂的组合为25 mg/kg L-肉碱、500 mg/kg纤维素酶、250 mg/kg植酸酶时,可提高机体CP沉积率,植酸酶是影响机体CP沉积的主效因子;当组合为50 mg/kg L-肉碱、1 000 mg/kg纤维素酶、350 mg/kg植酸酶时,能够改善机体EE沉积率,纤维素酶是影响机体EE沉积的主效因子。由此可见,在本试验条件下,肉鸡日粮中添加75 mg/kg L-肉碱、1 000 mg/kg纤维素酶、150 mg/kg植酸酶,可提高肉鸡营养物质代谢率;添加25 mg/kg L-肉碱、500 mg/kg纤维素酶、250 mg/kg植酸酶,有利于肉鸡机体营养物质的沉积。

植酸酶高剂量添加条件下日粮不同微量元素含量对笼养肉鸡生长与屠宰性能的影响

试验旨在研究日粮高剂量添加植酸酶情况下不同微量元素含量对笼养肉杂鸡生长性能与屠宰性能的影响。将864只1日龄公鸡随机分为2个组(对照组日粮添加铜10 mg/kg,铁60 mg/kg,锰60 mg/kg,锌80 mg/kg,碘0.8 mg/kg,硒0.30 mg/kg;试验组微量元素添加量减半),每组8个重复,每个重复54只鸡。试验周期50 d。研究结果表明:日粮添加2000 IU/kg植酸酶,试验组日粮微量元素减量添加后能显著(P<0.01)改善肉杂鸡的耗料增重比与日均增重,但是对肉杂鸡日均采食量无显著改善(P>0.05)。日粮中不同的微量元素添加量对肉杂鸡的屠宰率、全净膛率、胸肌率、腹脂率均无显著(P>0.05)影响。总之,在植酸酶高剂量添加的情况下降低日粮微量元素添加量对笼养肉杂鸡生长性能无负面影响,对日均增重和耗料增重比有明显的改善作用。

植物乳杆菌植酸酶理性设计及表达鉴定

植酸酶能将植酸水解成肌醇衍生物,并释放出无机磷酸,是一种重要的生物催化剂。植酸酶的热稳定性和比活性是决定其潜在应用价值的2个关键因素。该研究从植物乳杆菌中克隆到了具有233个氨基酸残基、高活性的植酸酶基因(LpPHY233),并在大肠杆菌中实现了高水平的异源表达,其表达水平是植物乳杆菌的800倍。基于理性设计的结果,通过二硫键工程显著提高了Lp PHY233的温度特性和催化性能。突变体Lp PHY233S58C/K61C的最适反应温度较Lp PHY233提高了15℃。此外,它还具有良好的pH特性和动力学参数,在食品加工和饲料添加剂领域具有较大的应用前景。该研究结果为植酸酶的进一步分子修饰和工业应用提供了坚实的理论基础。

植酸酶对日粮铜减量下肉鸡生产性能和Cu、Zn排泄量的影响

植酸是广泛存在于植物饲料原料中的抗营养物质,常与Cu^(2+)、Zn^(2+)、Fe^(2+)、Ca^(2+)、Mg^(2+)等离子螯合降低畜禽对矿物元素的生物利用率。植酸酶可以有效降解植酸,进而释放被螯合的金属元素,改善Cu、Zn等的利用率,同时降低排泄量。本试验旨在确定添加植酸酶对日粮Cu水平减量下肉鸡生产性能和Cu、Zn等元素排放效应的影响。试验选取1日龄体重均匀、健康的雄性肉仔鸡480只,随机分为3个处理组,每个处理8个重复。对照组(CON)饲喂标准试验日粮(Cu,8 mg·kg^(-1)),两个试验组日粮Cu添加水平分别为4 mg·kg^(-1)(50%Cu)和0 mg·kg^(-1)(0%Cu),同时添加1200 U·kg^(-1)植酸酶。测定肉鸡生产性能及血液、骨骼中Cu、Zn等元素含量,于4周和7周时进行代谢试验测定Cu、Zn表观利用率和粪便排泄量。结果表明,降低日粮铜水平下添加植酸酶对各阶段肉鸡的生产性能均无显著影响(P>0.05),各处理组间肝和胫骨中Cu、Zn沉积量均无明显差异(P>0.05),但对21 d肉鸡胫骨指数有促进作用(P=0.07),21 d时0%Cu组较CON组胫骨Mn含量显著升高(P<0.05);第4周两个Cu减量组肉鸡Ca、P和Cu、Zn、Mn的表观生物学利用率均显著提高(P<0.05),且Cu和Ca、P表观利用率提高呈现剂量效应,第7周50%Cu组Cu、Zn表观利用率显著高于CON组(P<0.05);与CON组相比,0%Cu和50%Cu组肉鸡4周龄Cu、Zn、Mn的排泄量均显著降低(P<0.05),7周龄时Cu排泄量显著减少(P<0.05)。综上所述,日粮中添加1200 U·kg^(-1)植酸酶在Cu水平降低至标准添加量的50%或0%时对肉鸡的生产性能没有明显影响,但可以提高日粮Cu、Zn的表观利用率,减少粪便Cu、Zn的排泄。

非植酸磷和植酸酶水平对京红1号商品蛋鸡43~62周龄产蛋性能和蛋壳质量的影响

试验旨在研究非植酸磷和植酸酶水平对京红1号商品蛋鸡43~62周龄产蛋性能和蛋壳质量的影响。试验选用产蛋率、体重相近的43周龄京红1号商品蛋鸡1152只,随机分为对照组、试验A组、试验B组、试验C组、试验D组、试验E组6个处理组,每组8个重复,每个重复24只,饲喂玉米-豆粕型饲粮,饲粮非植酸磷水平分别为0.24%、0.17%、0.17%、0.21%、0.21%、0.27%,植酸酶水平分别为750 U/kg、750 U/kg、1500 U/kg、750 U/kg、1500 U/kg、750 U/kg,预试期3周,正试期17周。结果显示:饲粮非植酸磷和植酸酶水平对蛋鸡平均日采食量、平均蛋重、平均日产蛋量、沙皮蛋率、不合格蛋率、蛋壳厚度无显著影响(P>0.05),而对蛋壳强度、蛋壳光泽度有显著影响(P<0.05),其中试验C组46~62周龄蛋壳强度显著高于试验A组和试验E组(P<0.05),试验D组51~52周龄蛋壳强度显著高于试验A、B、E组(P<0.05),试验C组49~50周龄、55~58周龄光泽度显著高于试验A组(P<0.05)。试验C组46~62周龄沙皮蛋率和不合格蛋率均最低。研究表明,玉米-豆粕型饲粮非植酸磷和植酸酶水平分别为0.21%、750 U/kg时,能够提高京红1号商品蛋鸡46~62周龄蛋壳强度和光泽度,降低不合格蛋率。

Effects of a novel bacterial phytase expressed in Aspergillus Oryzae on digestibility of calcium and phosphorus in diets fed to weanling or growing pigs

In 2 experiments, 48 weanling （initial BW： 13.5 ± 2.4 kg, Exp. 1） were used to determine effects of a novel bacterial 6-phytase and 24 growing pigs （initial BW： 36.2 ± 4.0 kg, Exp. 2） expressed in Aspergillus oryzae on the apparent total tract digestibility （ATTD） of phosphorus and calcium in corn-soybean meal diets fed to weanling and growing pigs. In Exp. 1 and 2, pigs were randomly allotted to 6 dietary treatments using a randomized complete block design and a balanced 2 period changeover design, respectively. In both experiments, 6 diets were formulated. The positive control diet was a corn-soybean meal diet with added inorganic phosphorus （Exp. 1：0.42 and 0.86% standardized total tract digestible phosphorus and total calcium, respectively; Exp. 2：0.32 and 0.79% standardized total tract digestible phosphorus and total calcium, respectively）. A negative control diet and 4 diets with the novel phytase （Ronozyme HiPhos, DSM Nutritional Products Inc., Parsippany, N J） added to the negative control diet at levels of 500, 1,000, 2,000, and 4,000 phytase units （FYT）/kg were also formulated. In Exp. 1, the ATTD of phosphorus was greater （P 〈 0.01） for the positive control diet （60.5%） than for the negative control diet （40.5%）, but increased （linear and quadratic, P 〈 0.01） as phytase was added to the negative control diet （40.5% vs. 61.6%, 65.1%, 68.7%, and 68.0%）. The breakpoint for the ATTD of phosphorus （68.4%） was reached at a phytase inclusion level of 1,016 FYT/kg. In Exp. 2, the ATTD of phosphorus was greater （P〈 0.01） for the positive control diet （59.4%） than for the negative control diet （39.8%） and increased （linear and quadratic, P〈 0.01） as phytase was added to the negative control diet （39.8% vs. 58.1%, 65.4%, 69.1%, and 72.8%）. The breakpoint for the ATTD of phosphorus （69.1%） was reached at a phytase inclusion level of 801 FYT/kg. in conclusion, the novel bacterial 6-phytase improved the ATTD of phosphorus and calcium in both weanling and growing pigs. The optimum level of inclusion for this phytase is 800 to 1,000 FYT/kg of complete feed to maximize ATTD of phosphorus and calcium in weanling and growing pigs

The Effect of Dietary Supplementation with Phytase Transgenic Corn on Growth Performance,Phosphorus Utilization and Excretion in Growing Pigs (Sus scrofa)

Two experiments were conducted to investigate the effect of dietary supplementation with phytase transgenic corn （PTC） on growth performance,phosphorus （P） utilization and excretion in growing pigs.In Exp.1,180 pigs （Large White × Landrace,BW=37.7 kg） were randomly allotted to 4 treatments with 5 replicates of 9 pigs each in order to evaluate the effect of PTC supplementation in low-P diets on growth performance.Four corn soybean meal-based diets consisted of a positive control （PC） diet,a diet containing 500 units （U） of exogenous phytase kg-1 （EP） on the basis of low-P （inorganic P reduced by 0.05% from PC diet） and the low-P＋500 （PTC1） or 750 （PTC2） phytase U of PTC kg-1.In Exp.2,20 barrows （Large White×Landrace,BW=31 kg,4 treatments with 5 replicates of 1 pig each） were randomly selected to evaluate the effect of PTC in low-P diets on serum parameters and nutrient utilization.Diets in Exp.2 were similar to those in Exp.1 except that the EP group was replaced by a low-P diet without exogenous phytase supplementation as a negative control （NC） group.The results from Exp.1 showed that the average daily gain （ADG） in the PTC2 group was significantly higher （P〈0.05） than that in the EP group over all periods.On the other hand,the feed：gain （F：G） ratio of the EP group was significantly higher （P〈0.05） than that of the PTC2 group during 1-21 and 1-42 d,respectively.There were no differences in average daily feed intake （ADFI） among all treatments （P〉0.05）.The results from Exp.2 showed that the concentration of serum Ca in the NC group was the highest （P〈0.05）,while the concentration of serum P in the PTC2 group was the highest （P〈0.05） among all treatments.There was a significant decrease （P〈0.05） in the P apparent digestibility of the NC group compared with the other groups,and that of PTC2 group was the best.Furthermore,fecal P excretion was reduced （P〈0.05） from 1.80 g d-1 in the PC group to 1.28 g d-1 in the PTC2 group.In conclusion,dietary supplementation with PTC could reduce the application of inorganic P,decrease fecal P excretion,and improve the growth performance of growing pigs.

Transgenic rice expressing a novel phytase-lactoferricin fusion gene to improve phosphorus availability and antibacterial activity

The developing trends of livestock production are efficiency availability of phytate phosphorus and abuse of antibiotics. safety and sustainability, which face two major challenges： low As a solution phytases and antimicrobial peptides are applied as feed additives. However, phytases and antimicrobial peptides are susceptible to proteases, costly by fermentation and potential toxic to production hosts. We transformed an optimized phytase-lactoferricin fusion gene PhyLfdriven by an en- dosperm-specific promoter Gt13aP and Bar （bialaphos resistance） gene as a selection maker into rice. The Bar and PhyLf genes were integrated into the rice genome, stably inherited and expressed. Their phosphinothricin acetyl transferase （PAT） protein content oftransgenic plants with glufosinate resistance varied between 50.45-93.39 IJg g-l. Fusion protein expressed especially in the seeds of transgenic rice had a summit phytase activity at 32.30 U g-l, which increased by 61.71-fold com- pared to the control/check group （CK） and 7.54-fold compared to un-optimized transgenic plant. The highest inorganic phosphorus （Pi） content of the transgenic seeds reached 13.15 mg g-~, increased by 12.77-fold compared to that of CK. Preliminary antibacterial experiments showed that the enterokinase hydrolysate product of fusion protein could inhibit the growth of Escherichia coil DH5a. These results indicated that the protein PhyLf has the potential to increase availability of feed phytate phosphorus, improve consumer＇s immunity and reduce the use of antibiotics.

Molecular Characterization and Functional Analysis of OsPHY1,a Purple Acid Phosphatase (PAP)-Type Phytase Gene in Rice (Oryza sativa L.)

As a specific type of acid phosphatses, phytases play diverse roles in plants by catalazing the degradation of phytic acid and its derivatives. In this study, a rice phytase gene referred to OsPHY1 has been functionally characterized. OsPHY1 contains a 1 620 bp of open reading frame, encoding a 539-aa polypeptide. A conserve domain metallophosphatase （MPP） （MPP_PAPs）, generally harbored in phytase and purple acid phosphatases （PAP）, was identified in OsPHY1 （residue 194-398）. Phylogenetic analysis revealed that OsPHY1 shares high similarities with phytase genes and PAP-type genes that derived from diverse plant species. The OsPHY1 transcripts were detected to be abundant in germinating seeds, suggesting that this gene plays potential roles on degradation of seed phytic acid and its derivatives during the germination process. Biochemical analysis confirmed that OsPHY1 possesses strong catalytic activities on phytic acid-Na2, with optimal temperature of 57°C and suitable pH of 3.5. Based on transgene analysis, the putative role of OsPHY1 in plants on utilization of phytate was assessed. Under the condition that phytic acid-Na2 was used as sole P source, the OsPHY1-overexpressing tobacco plants behaved higher phytase activities, higher concentrations of Pi, more accumulative amount of total phosphorus, and much more improved growth traits than those of the control plants. Therefore, OsPHY1 is acted as an important component on degradation of the phytins during the seed germination process in rice. Also, OsPHY1 has a potential use on generation of elite crop germplasms with improved use efficiencies on phytate and its derivatives.

Nonphytate Phosphorus Requirement and Efficacy of a Genetically Engineered Yeast Phytase for Yellow Broilers at 22- to 42-d-Old Age

An experiment was conducted to investigate the requirement of nonphytate phosphorus（nPP） and efficacy of a genetically engineered yeast phytase（PHY A） for Lingnan yellow broilers from 22-to 42-d-old age.A total of 1 320 1-d-old male chicks were randomly divided into 11 dietary treatment groups,which consisted of 4 replicate floor pens with 30 birds per pen.The control group（treatment 1） was fed with basal diet of nPP 0.08% without dicalcium phosphate or phytase supplementation.Dietary levels of nPP were 0.16,0.24,0.32,0.40,0.48,and 0.56%,respectively,for treatments 2 to 7,through addition of dicalcium phosphate（chemistry grade） to the basal diet.Diets of treatments 8 to 11 were supplemented with PHY A at 200,400 and 600 U kg-1,a commercial phytase product（PHY B） at 400 U kg-1 level,respectively.The birds in 0.32-0.56% nPP groups gained more than those of the other groups（P0.05）.The nPP supplementation significantly improved feed intake（P0.05）.The feed gain ratio was significantly decreased by 0.40% nPP diet compared to the control birds（P0.05）.The level of 0.48% nPP was required for optimum tibia development.The additions of PHY A at 400 and 600 U kg-1 level and PHY B all significantly improved ADG（P0.05）,ADFI（P0.05）,and dry defatted tibia weight（P0.05）.Similarly,the percentage of tibia ash was increased by 600 U kg-1 PHY A supplementation（P0.05）.The requirement of nPP for maximal ADG and highest percentage tibia ash both was 0.40%.The phosphorus equivalency value of PHY A was estimated as 685 U kg-1 for male yellow broilers of 22-to 42-d-old age.

Effects of Fermentation Product Containing Phytase on Productive Performance,Egg Quality,and Phosphorous Apparent Metabolism of Laying Hens Fed Different Levels of Phosphorus

This study investigated the effects of fermentation product containing phytase （FPP） that was fermented using waste vinegar residue （WVR） as substrate from Aspergillusficuum NTG-23 on productive performance, egg quality, and phosphorus apparent metabolism of laying hens. First, 375 22-wk-old Jinghong hens were allocated into 5 treatments （5 replicates of 15 hens each） in an 8-wk experiment for evaluating the parameters of productive performance, egg quality, serum, and tibia. Experimental diets contained 4% FPP and 96% corn-soybean diet. The levels of dicalciurn phosphate （DCP） were 1.34, 1.01, 0.67, 0.34 and 0%. Next, thirty 31-wk-old Jinghong hens were fed 5 types of diets for evaluating phosphorous apparent metabolism rate. Egg productive rate, egg weight, feed conversion ratio, Haugh unit, egg albumen height, serum calcium, tibia ash, tibia ash calcium and tibia breaking strength were not different significantly among 5 treatments. The significant difference of average daily feed intake was not appeared when the DCP content of corn-soybean-FPP diet was reduced to 0.67%; the eggshell hardness, eggshell thickness and serum phosphorus were not reduced significantly until the DCP content of corn-soybean-FPP diet was reduced to 0.34%. The yolk color was improved when the laying hens fed deficient DCP corn-soybean-FPP diet. A 22.14% reduction in excreta phosphorus was observed when the laying hens fed low phosphorus （0.67% DCP） corn-soybean-FPP diet. A 30% elevation of phosphorus apparent metabolism rate was obtained when the DCP content of corn-soybean-FPP diet was decreased from 1.34 to 1.01%. The reducing cost of layer diet was totalized about 120 CNY 1000 kg1 diet when the content of DCP was 0.67% in corn-soybean-FPP diet. These results indicated that FPP could be applied in laying hen as a potential, cost-effective and rational application of WVR.

Performance and Nutrient Utilization of Layers Fed Diet Supplemented with Microbial Phytase and Cellulase

A 31 week feeding trial was conducted to investigated the effects of dietary supplementation of microbial phytase and cellulase on performance,nutrients utilization and tibia quality of laying hens fed maize and soybean meal diets.192 18 week old Hisex layers were used in the trial A 2×2×2 factorial design was used in the experiment with three factors of two levels each:0 38% and 0 16% of dietary non phytate P(nP).0 and 300 U·kg -1 of phytase (Ph),and 0 and 0 10% of cellulase (Ce).The results showed that supplementation of 300 U·kg -1 phytase significantly improved utilization of dietary crude ash,CP,Ca,total P and copper (P<0 05),and improved tibia breaking strength (P<0 05).No effect of phytase on performance was observed.Addition of 0 10% cellulase decreased feed intake (P<0 05),increased utilization of CF (P<0 05) and Ca(P<0 01),and decreased total tibia ash weight (P<0 05).300 U·kg -1 phytase and 0 10% cellulase exhibited obvious positive interactions to enhance utilization of dietary phytic P and copper (P<0 05).0 16% nP did not reduce performance of the layers,but improved egg shell quality at 20 wks,increased utilization of dietary total P,phytic P and Copper (P<0 01),decreased utilization of dietary CP,increased tibia breaking strength and Ca,Mn contents of tibia(P<0 01)

Microbial Phytases and Phytate: Exploring Opportunities for Sustainable Phosphorus Management in Agriculture

Myo-inositol phosphates (phytates) are important biological molecules produced largely by plants to store phosphorus. Phytate is very abundant in many different soils making up a large portion of all soil phosphorus. This review assesses current phytase science from the perspective of its substrate, phytate, by examining the intricate relationship between the phytate-hydrolyzing enzymes and phytate as their substrate. Specifically, we examine available data on phytate’s structural features, distribution in nature and functional roles. The role of phytases and their localization in soil and plant tissues are evaluated. We provide a summary of the current biotechnological advances in using industrial or recombinant phytases to improve plant growth and animal nutrition. The prospects of future discovery of novel phytases with improved biochemical properties and bioengineering of existing enzymes are also discussed. Two alternative but complementary directions to increase phosphorus bioavailability through the more efficient utilization of soil phytate are currently being developed. These approaches take advantage of microbial phytases secreted into rhizosphere either by phytase-producing microbes (biofertilizers) or by genetically engineered plants. More research on phytate metabolism in soils and plants is needed to promote environmentally friendly, more productive and sustainable agriculture.

Transgenic Expression of the Recombinant Phytase in Rice (Oryza sativa)

In most of the cereal crop, phytic acid is the main storage form of phosphorus, which can decrease the bioavailability of phosphate. Transgenic expression of phytase is regarded as an efficient way to release phosphate from phytate in transgenic plants. In this study, a plant expression vector, containing the recombinant phytase gene driven by the maize ubiquitin （Ubi） promoter was constructed and introduced into an elite rice variety via Agrobacterium-mediated transformation. During the experiment, a total of 15 independent transgenic rice lines were regenerated. The results of PCR and Southern blot indicated that the target gene was integrated into the genome of transgenic rice plants. Moreover, the RT-PCR analysis of total RNAs extracted from the immature seeds of several transgenic lines showed that the recombinant phytase gene could be normally expressed. The inorganic phosphorus content, both in the mature seeds and the leaf was significantly higher in the transgenic plants than in the untransformed wild type.

Optimization of Culture Conditions to Produce Phytase from <i>Aspergillus tubingensis SKA</i>

The effects of nutrients and physical conditions on phytase production were investigated with a recently isolated strain of Aspergillus tubingensis SKA under solid state fermentation on wheat bran. The nutrient factors investigated included carbon source, nitrogen source, phosphate source and concentration, metal ions (salts) and the physical parameters investigated included inoculum size, pH, temperature and fermentation duration. Our investigations revealed that optimal productivity of phytase was achieved using wheat bran supplemented with: 1.5% glucose. 0.5% (NH4)2SO4, 0.1% sodium phytate. Additionally, optimal physical conditions were 1 × 105 spore/g substrate, initial pH of 5.0, temperature of fermentation 30°C and fermentation duration of 96 h. Overall, a 34% improvement in phytase activity was achieved by using the optimal conditions.

微生物植酸酶及其对土壤植酸的矿化作用综述

有机磷是土壤磷的主要存在形式,占比40%—90%,是作物磷营养的重要来源和储备库,亦是引起水体富营养化的潜在因子.磷作为植物生长发育的必需大量营养元素,通常以无机磷肥形式施用于土壤,易吸附于土壤表面或与钙、镁、铝、铁等金属阳离子形成难溶性络合物,导致其生物可利用性降低,其中20%—80%磷肥转化为有机磷,不易被植物吸收利用.矿化作用是在土壤微生物作用下,土壤中有机态化合物转化为无机态化合物的总称.土壤中有机磷主要以植酸及其盐类形式存在(占比50%—70%),植酸(盐)可被专一性酶(植酸酶)矿化水解为肌醇和磷酸(盐),并释放出无机磷,以供植物的根系直接吸收和利用.前期研究发现,缺磷胁迫下微生物可大量分泌植酸酶分解植酸,释放磷酸根,促使土壤有机磷水解矿化为无机磷,提高了土壤有机磷的生物可利用率.目前关于微生物植酸酶矿化植酸的研究多集中于谷类作物和动物营养,对土壤植酸矿化与土壤有机磷利用的综述性报道较少.因此,本文主要关注微生物植酸酶对土壤植酸的矿化作用与土壤有机磷利用,重点阐述其过程、机制和效率,包括微生物植酸酶的种类来源、酶学性质、作用机理和实际应用等方面的研究进展,可为提高土壤有机磷的生物利用效率、减少农业磷肥施用量、降低土壤磷流失及水体污染风险提供理论依据和技术支撑,为深入探究植酸酶功能并应用于农业生产实践及保障生态环境安全提供基础信息和参考.

Effects of phytase supplementation on growth performance, slaughter performance, growth of internal organs and small intestine, and serum biochemical parameters of broilers

The objective of this study was to investigate the effects of phytase supplementation on growth performance, slaughter performance, growth of internal organs and small intestine, and serum biochemical indices of broilers. A total of 360 1-day-old Ross 308 broilers were randomly divided into 4 groups with 3 replicates and 30 broilers per replicate (15 male, 15 female). The treatments were fed with basal diet supplemented with 0%, 0.01%, 0.02% and 0.03% phytase. The results showed that: 1) Phytase supplementation increased the body weight gain and the body weight of Ross 308 broilers (P serum calcium (Ca) consistency was 0.02%. According to the above analysis, the feasible supplementation of phytase (enzyme activity for 5000 u/g) in broiler dietary was 0.02%.