2.5次微分伏安法对生物样品中丙二醛的测定

以0.1mol/L NH₄Cl溶液为介质, 用2.5次微分伏安法测定了丙二醛, 线性范围为1.0×10^-6至1.0×10^-3 mol/L, 检测限达1.0×10^-7 mol/L. 并测定了细胞培养液介质中新生SD大鼠心室肌细胞样品中的丙二醛.     

外源CaCl2对NaCl胁迫下酸枣幼苗氮代谢的影响

为了研究CaCl₂对NaCl胁迫下酸枣幼苗根、茎、叶的氮代谢影响,探索钙缓解幼苗NaCl胁迫的作用途径。该研究以酸枣幼苗为试验材料,检测不同浓度CaCl₂(0、5、10、20 mmol/L)对NaCl(150 mmol/L)胁迫下幼苗叶片H₂O₂、O^-·₂含量,根、茎、叶中硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)活性及游离氨基酸、可溶性蛋白、硝态氮含量的影响,并采用主成分分析法筛选出评价CaCl₂缓解NaCl胁迫效应的生理指标。结果表明：与NaCl胁迫相比,盐胁迫幼苗叶片的H2O₂、O^-·₂积累量在5、10 mmol/L CaCl₂处理下显著减少;GOGAT活性在5、10 mmol/L CaCl₂处理下的植株根和茎内以及各浓度 CaCl₂处理的叶内均显著升高, GS、NR活性在10、20 mmol/L CaCl₂处理的根内和10 mmol/L CaCl₂处理的茎内以及5、10、20 mmol/L CaCl₂处理的叶内均显著升高;可溶性蛋白含量在5、10、20 mmol/L CaCl₂处理的根、茎、叶内均显著升高,游离氨基酸含量在10、20 mmol/L CaCl₂处理的根和茎内以及10 mmol/L CaCl₂处理的叶内均显著升高,硝态氮含量在10 mmol/L CaCl₂处理的根和茎内以及5、10、20 mmol/L CaCl₂处理的叶内均显著升高。研究发现,150 mmol/L NaCl胁迫对酸枣幼苗造成明显过氧化伤害,抑制了体内氮代谢;外源CaCl₂可通过促进幼苗根和茎内GS/GOGAT循环对NH₄⁺的同化作用,提高叶片NR活性,加快硝态氮的转化速率,从而增强幼苗对NaCl胁迫的适应性,并以10 mmol/L CaCl₂处理缓解效果最佳;游离氨基酸、GOGAT、NR可以作为CaCl₂缓解幼苗NaCl胁迫伤害的评价指标。     

油菜素内酯浸种对盐胁迫番茄种子萌发的影响及其生理机制

为揭示油菜素甾醇类化合物提高作物耐盐的效应和机理,研究了10^-11、10^-10、10^-9、10^-8、10^-7、10^-6、10^-5 mol/L 2,4-表油菜素内酯（EBL）浸种处理对0、50、100、150、175 mmol/L NaCl胁迫7 d的番茄种子萌发、生长、溶质积累、抗氧化代谢的影响。结果显示：NaCl浓度越高的盐胁迫下,10^-9 mol/L EBL浸种可体现出越显著的促进番茄种子萌发的效应;在所有处理下,EBL浸种浓度过高,即10^-6、10^-5 mol/L EBL,均表现出对种子萌发的抑制效应。盐胁迫下种子萌发后,一定浓度的EBL浸种可表现出明显的增加种子胚根和下胚轴长,提高萌发种子鲜重和种子活力指数,其中10^-9 mol/L EBL浸种处理促进效果最适;EBL浸种浓度过高,则表现出抑制效应。150 mmol/L NaCl胁迫或非盐胁迫下,10^-9 mol/L EBL浸种均可降低萌发种子体内的O₂^·-、H₂O₂、丙二醛（MDA）和脯氨酸（Pro）含量;盐胁迫下,10^-9 mol/L EBL浸种可显著提高萌发种子可溶性糖（SS）和可溶性蛋白（SP）的含量。150 mmol/L NaCl胁迫或非盐胁迫下,10^-9 mol/L EBL处理可不同程度促进番茄种苗超氧化物歧化酶（SOD）和过氧化物酶（POD）活性的上升。综上所述,盐胁迫下,一定浓度范围内的EBL浸种可明显促进番茄种子萌发或成苗,其中以10^-9 mol/L EBL浸种的效果最好,主要是因为EBL施用可积极促进番茄种子萌发中物质转化,SS和SP等溶质积累增多,增强其渗透调节能力;同时SOD和POD酶活增强,缓解盐胁迫导致番茄种子萌发中的次生氧化胁迫。     

保水功能菌枯草芽胞杆菌LX-1固态发酵的工艺优化

γ-聚谷氨酸(γ-PGA)对土壤保水和提高植物抗逆性具有明显作用,为了利用农产品加工下脚料发酵生产含有γ-PGA的保水功能肥料,对福建省微生物研究所环境微生物研究室分离到的产γ-PGA的枯草芽胞杆菌(Bacillus subtilis)LX-1的固态发酵培养基配比进行优化。实验以发酵产物的荧光素双醋酸酯酶(FDA)酶活和增比黏度为指标,在通过单因素实验选定固态发酵料的碳源、氮源、无机盐溶液的最佳配比以及无机盐较佳添加量的基础上,通过拟水平均匀设计U₇* (7⁴试验,得出菌株LX-1固态发酵的最佳培养基配方：V豆粕V麦麸V无机盐溶液=644,其中无机盐溶液的最佳配方为K₂HPO₄·3H₂O 5.24 g/L、MgSO₄·7H₂O 0.78 g/L、NaCl 11.67 g/L。为利用农产品加工下脚料发酵生产含γ-PGA保水肥料提供参考。     

饲料中黄曲霉毒素B1、G1和棕曲霉毒紊A的薄层层析测定法

饲料样品25g,用100 ml乙睛:4%氯化钠溶液(9:1)抽提,吸取25 ml提取液,以石油醚脱脂二次,加0.1mol/L碳酸氢钠溶液12.5ml后,用氯仿提取二次,氯仿层放入蒸发皿中,于60℃水浴挥干,残渣以苯乙睛溶解定容为1ml,供测定黄曲霉毒素B₁、 G₁。碳酸氢钠水层中加1mol/L盐酸1ml左右调节pH值为4-5,再以氯仿提取二次,氯仿层放人蒸发皿中,于60℃水浴挥干,残渣以苯乙酸溶解定容至1ml,供测定棕曲霉毒素A。黄曲霉毒素B₁、 G₁的薄层板以乙醚横展、丙酮氯仿纵展。棕曲霉毒素A的薄层板以丙酮氯仿横展,甲苯乙酸乙醋90%甲酸纵展。展板后分别在波长为365nm和254nm的紫外光下观察。如为阳性样品,标记后用薄层扫描仪定量。棕曲霉毒素A阳性样品应先喷碳酸氢钠乙醇溶液后再扫描。本测定方法对三种毒素的最低检出量均为0.2ng/点,最低检出狠量均为3.2ppb。     

用Blue Sepharose CL-6B快速纯化天花粉蛋白

差光谱显示染料cibacron blue F3GA与天花粉蛋白(TCS)有特异性结合,复合物在可见光部分的最大吸收波长在690 nm,摩尔消光系数ε=2.6×10^-3(mol/L)^-1·cm^-1,解离常数K_d=1.8 μmol/L,0.5 mol/L NaCl可使复合物解离.根据这一特点,用Blue-Sepharose CL-6B凝胶从栝篓块茎中亲和纯化了TCS.此法快速、简便、高效,易于大量制备.     

谷氨酸棒状杆菌尿素传感器的研究

基于腺酶催化尿素分解产生氨,以氨气敏电极为基础电极,用含脲酶丰富的谷氨酸棒状杆菌研制成测定尿素的微生物传感器.在30℃、pH8.0、0.1mol/L磷酸盐缓冲液中,该传感器的线性范围为1.1×10^-4～1.4×10^-2mol/L,斜率为51.2mV/decade,检测下限为1.0×10^-5mol/L,寿命可达45d.考察了传感器响应初速和底物浓度之间的关系,测定了微生物膜中脲酶的表观米氏常数K_m及最大响应初速v_m.     

外源H2O2对盐胁迫下小白菜种子萌发和幼苗生理特性的影响

以小白菜"甜脆青"为试材,研究不同浓度（5、10、25、50和100 mmol/L）过氧化氢（H₂O₂）浸种处理对100 mmol/L NaCl胁迫下小白菜（Brassica chinensis L.）种子萌发、幼苗生长及生理特性的影响。结果表明：100 mmol/L NaCl胁迫明显抑制小白菜种子的萌发状况和幼苗生长,发芽势、发芽指数、活力指数及幼苗根和芽长度和鲜重均明显降低,根和芽中CAT的活性及K⁺含量明显受到抑制,渗透调节物质、活性氧和MDA含量显著增加。不同浓度H₂O₂浸种处理提高了NaCl胁迫下小白菜种子发芽势、发芽指数和活力指数,促进小白菜根和芽的生长,增强了NaCl胁迫下根和芽中SOD、CAT和APX的活性及K⁺含量,降低O₂^-·产生速率及H₂O₂和MDA含量,进一步促进脯氨酸和可溶性糖含量的增加,降低体内Na⁺含量。其中以10 mmol/L H₂O₂处理缓解盐胁迫效果最好,明显缓解NaCl胁迫对小白菜种子萌发和幼苗生长的抑制。     

基因工程菌Pichia pastoris高密度培养条件研究*

基因工程菌pichiapastoris最佳种子培养基为添加 4mL/LPTMl的BMGY培养基 ;全合成高密度摇瓶培养基是甘油 4% ,(NH₄) ₂ SO₄1 0g/L ,CaSO₄0 .93g/L ,K₂ SO₄1 8.2g/L ,MgSO₄·7H₂O 1 4.9g/L ,0 1mol/L磷酸缓冲液 (pH =6     

外源H2O2对盐碱胁迫下苹果矮化砧木幼苗生理特性的影响

以2年生苹果矮化砧木M9 T337为试材,采用盆栽试验法,设置浇灌清水(CK)和盐碱胁迫(0.1 mol/L NaCl+NaHCO₃溶液)+ 喷施5种浓度的H₂O₂ ［0(T₁)、0.2 mmol/L(T₂)、0.4 mmol/L(T₃)、0.6 mmol/L(T₄)、0.8 mmol/L(T₅)］ 处理,测定各处理叶片叶绿素含量、光合气体交换参数、渗透调节物质含量、抗氧化酶活性和细胞膜透性,并利用相关性与主成分分析进行综合评价,以探讨外源过氧化氢(H₂O₂)增强其盐碱耐性的生理机制。结果表明：(1)随着盐碱胁迫(T₁)的时间延长,M9 T337幼苗叶片叶绿素a(Chl a)含量、叶绿素b (Chl b)含量、叶绿素总量(Chl t)、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、可溶性蛋白(SP)含量均呈逐渐下降趋势;胞间CO₂浓度(C_i)、可溶性总糖(TSS)含量、脯氨酸(Pro)含量、过氧化氢酶(CAT)活性、抗坏血酸过氧化物酶(APX)活性、相对电导率(REC)、丙二醛(MDA)含量均呈上升趋势;超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性均呈先升后降趋势。(2)与CK相比,盐碱胁迫+外源H₂O₂(T₂- T₅)处理后M9 T337幼苗叶片各指标均呈现不同幅度变化,且存在明显浓度效应,并以T₃(0.4 mmol/L H₂O₂)处理叶片的Chl a、Chl b、Chl t、SP和G_s降幅最小,C_i、REC、MDA升幅最小,TSS、Pro、APX升幅最大。(3)M9 T337幼苗叶片P_n与T_r、G_s、Chl a、Chl b、Chl t、SP、SOD、POD呈显著正相关,与C_i、MDA、CAT、APX、REC呈显著负相关。(4)综合评价表明,各处理对M9 T337幼苗叶片生理特性的效应依次为：CK>T₃>T₄>T₂>T₅>T₁。研究发现,叶面喷施适宜浓度H₂O₂可有效改善盐碱胁迫下M9 T337幼苗光合能力,显著提高抗氧化酶活性和渗透调节物质的含量,降低细胞膜透性,从而达到缓解盐碱胁迫的作用,并以0.4 mmol/L H₂O₂处理效果最佳。     

Nanofiltration as a purification step in production process of organic acids: Selectivity improvement by addition of an inorganic salt

The aim of this study is to investigate to what extend the addition of an electrolyte (NaCl or Na₂SO₄) can improve the selectivity of the sodium lactate/glucose separation by nanofiltration. Experimental results were used to get the variation of the observed retentions versus the permeation flux and to evaluate the separation efficiency from the separation factor. In presence of NaCl, both glucose and lactate retentions slightly decrease and remain very close except at low permeation fluxes where the addition of NaCl has more effect on lactate retention than on glucose one. On the contrary, whilst the addition of Na₂SO₄ has no influence on glucose retention, a strong effect was pointed out on the lactate one, especially for high electrolyte concentrations for which negative retentions were obtained at low permeation fluxes. Then, the separation was much more improved by the addition of Na₂SO₄ compared to NaCl. A maximum separation factor of 1.9 was obtained with Na₂SO₄ at 0.25 M added to the glucose (0.1 M)/sodium lactate (0.1 M) solution whereas the separation was impossible without the addition of salt.     

Effects of Salt Stress on Photosynthetic Pigments and Activity of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase in <Emphasis Type="Italic">Kalidium foliatum</Emphasis>

The effects of NaCl and Na₂SO₄ on photosynthetic pigments, malondialdehyde (MDA), Rubisco activity and superoxide dismutase (SOD) activity were investigated in Kalidium foliatum (Pall.) Moq., which is distributed in the saline soil of Hetao irrigation area in Inner Mongolia China. The K. foliatum plants were treated with NaCl (0, 100, 250, 400 and 500 mM), Na₂SO₄ (0, 100, 250, 400 and 500 mM) and NaCl + Na₂SO₄ (1: 1, v/v) (0, 100, 250, 400 and 500 mM of Na⁺ concentration, 0, 50, 125, 200 and 250 mM of Cl^– and SO ₄ ^2– concentration) for 10 days. Content of chlorophylls and carotenoids were significantly higher than control at increasing NaCl and Na₂SO₄ concentration, in contrast, were significantly reduced by higher concentration of NaCl + Na₂SO₄. Rubisco activity reduced steadily at 100 and 250 mM NaCl, while increased at 400 and 500 mM NaCl. Rubisco activity was significantly higher than control at 100 mM Na₂SO₄, and was no more change under NaCl + Na₂SO₄ treatment. The SOD activity increased with increasing NaCl and Na₂SO₄, and increased at moderate NaCl + Na₂SO₄ treatment. MDA content was lower than control at 250 mM salt concentration. On the basis of the data obtained, K. foliatum showed resistance to salt such as Na⁺, Cl^–and SO ₄ ^2– , Rubisco activity in K. foliatum might be more sensitive to salt.     

Effects of NaCl and Na2SO4 on Water Relations ofPlantago maritima (L.) andPlantago lanceolata (L.)

Transpiration and water absorption rates, stomatal and cuticular resistances to water vapour diffusion, were measured onPlantago maritima (halophyte) andPlantago lanceolata (glycophyte) grown in the presence of NaCl or Na₂SO₄. Water absorption was reduced in the presence of Na₂SO₄ and transpiration rate was increased when NaCl was added to the nutrient solution. The glycophyte daily water balance was more disturbed than that of the halophyte in the presence of Na₂SO₄.     

Effect of inorganic salt stress on the thermotolerance and ethanol production at high temperature of <Emphasis Type="Italic">Pichia kudriavzevii</Emphasis>

Application of cross-protection is expected to improve the thermotolerance of yeasts to enhance their ethanol production at high temperature. In this study, the effects of eight kinds of inorganic salts on the thermotolerance and ethanol production at high temperature in Pichia kudriavzevii were investigated. P. kudriavzevii showed strong thermotolerance and the ability to produce ethanol at high temperature, and higher ethanol production of P. kudriavzevii was observed at high temperature (37–42 °C) compared with that at 30 °C. Inorganic salt stresses induced obvious cross-protection of thermotolerance in P. kudriavzevii. The presence of 0.1 mol/L KNO₃ or Na₂SO₄ or 0.2 mol/L NaCl, KCl, NaNO₃, K₂SO₄ or MgCl₂ increased the yeast biomass in YEPD medium at 44 °C to 2.72–3.46 g/L, obviously higher than that in the absence of salt stress (2.17 g/L). The addition of NaCl, KCl, NaNO₃, KNO₃, Na₂SO₄, K₂SO₄, CaCl₂ and MgCl₂ significantly increased the ethanol production of P. kudriavzevii in YEPD fermentation medium at 44 °C by 37–58%. KCl and MgCl₂ exhibited the best performance on improving the thermotolerance and ethanol production, respectively, of P. kudriavzevii. A highly significant correlation (P?<?0.01) was obtained among ethanol production, biomass and glucose consumption, suggesting the important role of thermotolerance and glucose consumption in enhanced ethanol production. The combination of NaCl, KCl and MgCl₂ had a synergistic effect on the improvement of thermotolerance and ethanol production at high temperature in P. kudriavzevii. This study provides some important clues for improving ethanol production of thermotolerant yeasts at high temperature.     

Salt stress effects on growth and mineral nutrition of French beans

An experiment was designed to study the effects of sodium chloride and sodium sulphate on growth and inorganic contents inPhaseolus vulgaris (L) cvVaghya. It was noted that except at 2.5 and 5 dS/m Na₂SO₄, other concentrations of both the salts proved to be inhibitory. NaCl lowered the chlorophyll content while opposite was the trend with Na₂SO₄. Both the salt caused an increase in leaf thickness and moisture content. Salt rich environment disturbed the normal inorganic metabolism. The contents of Na, Ca, Fe and Mg were greater while those of N, K, Cu and Zn were low. The contents of P and Mn showed a differential response.     

Effects of NaCl or Na<Subscript>2</Subscript>SO<Subscript>4</Subscript> salinity on plant growth,ion content and photosynthetic activity in <Emphasis Type="Italic">Ocimum basilicum</Emphasis> L.

Basil (Ocimum basilicum L., cultivar Genovese) plants were grown in Hoagland solution with or without 50 mM NaCl or 25 mM Na₂SO₄. After 15 days of treatment, Na₂SO₄ slowed growth of plants as indicated by root, stem and leaf dry weight, root length, shoot height and leaf area, and the effects were major of those induced by NaCl. Photosynthetic response was decreased more by chloride salinity than by sulphate. No effects in both treatments on leaf chlorophyll content, maximal efficiency of PSII photochemistry (F _v/F _m) and electron transport rate (ETR) were recorded. Therefore, an excess of energy following the limitation to CO₂ photoassimilation and a down regulation of PSII photochemistry was monitored under NaCl, which displays mechanisms that play a role in avoiding PSII photodamage able to dissipate this excess energy. Ionic composition (Na⁺, K⁺, Ca²⁺, and Mg²⁺) was affected to the same extent under both types of salinity, thus together with an increase in leaves Cl⁻, and roots SO₄ ²⁻ in NaCl and Na₂SO₄-treated plants, respectively, may have resulted in the observed growth retardation (for Na₂SO₄ treatment) and photosynthesis activity inhibition (for NaCl treatment), suggesting that those effects seem to have been due to the anionic component of the salts.     

Changes in growth and water-soluble solute concentrations in Sorghum bicolor stressed with sodium and potassium salts

Sorghum bicolor L. Moench, RS 610, was grown in liquid media salinized with NaCl, KCl, Na₂SO₄, K₂SO₄ or with variable mixtures of either NaCl/KCl or Na₂SO₄/K₂SO₄ at osmotic potentials ranging from 0 to -0.8 MPa. The purpose was to study the effects of different types and degrees of salinity in growth media on growth and solute accumulation. In 14-day-old plants the severity of leaf growth inhibition at any one level of osmotic potential in the medium increased according to the following order: NaCl < Na₂SO₄ < KCl = K₂SO₄. Inhibition of growth by mixtures of Na⁺ and K⁺ salts was the same as by K⁺ salts alone. Roots responded differently. Root growth was not affected by Na⁺ salts in the range of 0 to -0.2 MPa while it was stimulated by K⁺ salts. The major cation of leaves was K⁺ because S. bicolor is a Na⁺-excluder, while Na⁺ was the major cation in roots except at low Na⁺/K⁺ ratios in media. Anions increased in tissues linearly in relation to total monovalent cation, but not with a constant anion/cation ratio. This ratio increased as the cation concentrations in tissues increased. Sucrose in leaf tissue increased 75 fold in Chloride-plants (plants growing in media in which the only anion of the salinizing salts was Cl^?) and 50 fold in Sulphate-plants (the only anion of the salinizing salts was SO₄^2-). Proline increased 60 and 18 fold in Chloride- and Sulphate-plants, respectively, as growth media potentials decreased from 0 to -0.8 MPa. The concentrations of both sucrose and proline were directly proportional to the amount of total monovalent cation in the tissue. Sucrose concentrations began increasing when total monovalent cations exceeded 100 μmol (g fresh weight)^?1 (the monovalent cation level in non-stressed plants), but proline did not start accumulating until monovalent cation concentrations exceeded 200 μmol (g fresh weight)^?1. Therefore, sucrose seemed to be the solute used for osmotic adjustment under mild conditions of saline stress while proline was involved in osmotic adjustment under more severe conditions of stress. Concentrations of inorganic phosphate, glucose, fructose, total amino acids and malic acid fluctuated in both roots and leaves in patterns that could be somewhat correlated with saline stress and, sometimes, with particular salts in growth media. However, the changes measured were too small (at most a 2–3 fold increase) to be of importance in osmotic adjustment.     

Osmotic and ionic effects of NaCl and Na2SO4 salinity on Phragmites australis

Osmotic and ion-specific effects of NaCl and Na₂SO₄ on Phragmites australis (Cav.) Trin ex. Steud. were investigated in a laboratory experiment by examining effects of iso-osmotic solutions of NaCl and Na₂SO₄ on growth, osmolality of cell sap, proline content, elemental composition and gas exchange. Plants were supplied with a control standard nutrient solution (Ψ = −0.09 MPa) or solutions of NaCl or Na₂SO₄ at water potentials of −0.50, −1.09 or −1.74 MPa. Salt treatments increased root concentrations of Na and S or Cl, whereas P. australis had efficient mechanisms for exclusion of Na and S and partly Cl ions from the leaves. Incomplete exclusion of Cl from the leaves may affect aboveground biomass production, which was significantly more reduced by NaCl than Na₂SO₄. Stomatal conductance was negatively influenced by decreasing water potentials caused by NaCl or Na₂SO₄, implying that a non-significant photosynthetic depression observed in plants grown at −1.74 MPa was mainly due to osmotically induced stomatal closure. This was supported by decreasing internal CO₂ concentrations. Saline conditions increased the intrinsic water use efficiency and did not alter photosynthetic parameters derived from light response curves, supporting the assumption of a well-functioning CO₂ utilization in salt stressed plants. The leaf proline concentration increased equally in NaCl and Na₂SO₄-treated plants, and may play an important role as a compatible organic solute. P. australis possesses a range of mechanisms conferring tolerance to both NaCl and Na₂SO₄ stress and except in terms of growth the phytotoxicity of NaCl and Na₂SO₄ are comparable.     

Sodium is the critical factor leading to the positive halotropism of the halophyte Limonium bicolor

Previous studies indicate that the roots of nonhalophytes showed negative halotropism to salt stress to avoid salt damage. However, halotropism of euhalophytes and their possible reasons are little known. Limonium bicolor, a typical recretohalophyte with multicellular salt glands, was used to study halotropism compared with Arabidopsis thaliana under NaCl, KCl and Na₂SO₄ stress. The elongation of the roots in L. bicolor was significantly promoted by the appropriate concentrations of NaCl, KCl and Na₂SO₄, but those of A. thaliana was markedly inhibited. However, isosmotic mannitol with 200?mM NaCl did not affect the root growth of both L. bicolor and A. thaliana. The root activity of both L. bicolor and A. thaliana was enhanced by salts. Compared with K⁺, Cl^–, and SO₄^2?, Na⁺ played a critical role in halotropism of L. bicolor. Furthermore, the gravitropic setpoint angle of L. bicolor increased under NaCl, KCl and Na₂SO₄ treatments compared with controls, and the phenomenon was most apparent under NaCl treatments. The endogenous IAA content of the NaCl-treated L. bicolor seedlings was significantly higher than that of the controls. These results suggest that the recretohalophyte L. bicolor has positive halotropism and Na⁺ plays a pivotal role in L. bicolor’s positive root halotropism by regulating IAA.     

Influence of NaCl and Na2SO4 on the kinetics and dye decolorization ability of crude laccase from Ganoderma lucidum

In a solid state medium using yellow passion fruit waste as substrate, the basidiomycete Ganoderma lucidum produced a laccase as the main ligninolytic enzyme. This crude enzyme presented Michaelian behavior with both substrates tested, namely 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and the anthraquinone dye remazol brilliant blue R (RBBR). The K_M’s for these substrates were, respectively, 0.232 × 10⁻³ and 0.602 × 10⁻³ M. The actions of NaCl and Na₂SO₄, two important salts usually found in textile wastewaters, were investigated. The enzyme was inhibited by NaCl, but not by Na₂SO₄. Inhibition by NaCl was of the mixed type with two different inhibition constants. The enzyme was able to completely decolorize RBBR in the presence of 1.0 M Na₂SO₄ and 50% decolorization was found in the presence of 0.1 M NaCl. Such properties certainly make the enzyme a good agent for textile dye effluent treatment considering the fact that wastewaters of this industry usually contain high concentrations of NaCl and Na₂SO₄.