CN114752586B

CN114752586B - Algin lyase ALyI1 and application thereof

Info

Publication number: CN114752586B
Application number: CN202210318343.7A
Authority: CN
Inventors: 周燕霞; 张铭静; 贠帅婷; 彭力阳; 马雨
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2024-02-06
Anticipated expiration: 2042-03-29
Also published as: CN114752586A

Abstract

The algin lyase ALYI1 (32.15 kDa) cloned from sea cucumber enterobacteria Tamlanasp. ALYI1 belongs to polysaccharide lyase 7 family, and the enzyme has optimal activity at 40 ℃ and pH8.6, shows remarkable salt tolerance, keeps stable between 0.0 and 5.0M NaCl, has an anti-biofilm effect on pseudomonas aeruginosa, and can be used as a method for removing or inhibiting pseudomonas aeruginosa biofilm formation.

Description

Algin lyase ALyI1 and application thereof

Technical Field

The invention belongs to the technical field of biology, and particularly relates to algin lyase and application thereof.

Background

Pseudomonas aeruginosa is a gram-negative bacterium that can cause opportunistic infections in plants and animals. In addition to causing hospital-acquired and ventilator-associated pneumonia in hospitalized patients, pseudomonas aeruginosa is particularly severe in cystic fibrosis patients with impaired respiratory systems. Eradication of P.aeruginosa from the lungs of cystic fibrosis patients after infection is very difficult due to the delicate adaptation mechanisms of P.aeruginosa, including biofilm formation, resistance to antigen development, genomic plasticity, hypermutability, and various stages of toxicity at different stages of infection. The biofilm of pseudomonas aeruginosa comprises extracellular polysaccharide, pel, psl and algin. Pel consists of N-acetylgalactosamine and N-acetylglucosamine. Psl consists of galactose and mannose.

Algin is a linear acidic polysaccharide, which is an important component of the cell wall and intracellular material of brown algae (e.g., phaeophyceae). Structurally, it consists of an α -L-guluronate (G) and a β -D-mannuronate (M), linked by 1, 4-glycosidic bonds, the two sugar units being able to be combined in three modes, polyguluronate (polyG), polymannuronate (polyM) and heteropolymer block (polymg).

Algin lyase has a variety of sources including marine and terrestrial bacteria, fungi, viruses, brown algae, marine molluscs and echinoderms. Over the last few years, a number of algin lyase enzymes have been identified from bacteria. Based on the carbohydrate-active enzyme (CAZy) database, 14 Polysaccharide Lyase (PL) families (PL 5, 6, 7, 8, 14, 15, 17, 18, 31, 32, 34, 36, 39 and 41) have been classified, with the largest algin lyase family being the PL7 family.

Algin lyase is an enzyme that degrades algin by beta-elimination reaction to produce unsaturated products. The algin lyase is classified into an endo type and an exo type according to the catalytic manner. Algin lyase can be used to study the fine structure of algin, to produce polyM and polyG blocks of specific length or algin oligosaccharides, for specific applications in agriculture, biotechnology and medical industry, and to produce monosaccharides for biofuel production. Algin lyase enzymes have also been explored as biotherapeutic agents for cystic fibrosis, as they can increase the efficiency of antibiotics by scavenging algin in the biofilm matrix.

The research separates and purifies a new algin lyase from marine bacteria Tamlaasp.I1. Its related biochemical properties and its ability to act on Pseudomonas aeruginosa biofilms are reported. The enzyme has good salt tolerance.

Disclosure of Invention

In one aspect, the invention provides an algin lyase, the amino acid sequence of which has at least 95%, 96%, 97%, 98% or 99% sequence identity compared with seq id No. 2.

In one embodiment, the algin lyase is derived from a marine bacterium tamlanasp, e.g., marine bacterium tamlanasp.i1.

In one embodiment, the amino acid sequence of the algin lyase has at least 99% sequence identity compared to seq id No.2 and is derived from the marine bacterium tamlanassp.i1.

In a preferred embodiment, the amino acid sequence of the algin lyase is shown in SEQ ID No. 2.

On the other hand, the invention also provides a coding gene of the algin lyase, and preferably, the sequence of the gene is shown as SEQ ID No. 1.

In another aspect, the present invention also provides a recombinant vector comprising the above-described coding gene, preferably a recombinant expression vector, such as a pET series vector, e.g. pET-22b; as another example, pRSFDuet-1 vector.

In another aspect, the present invention also provides a recombinant strain comprising the recombinant vector described above, preferably, the recombinant strain is escherichia coli, such as escherichia coli BL21.

On the other hand, the invention also provides application of the algin lyase, the gene, the vector or the strain in degrading algin.

In one embodiment, the algin comprises sodium alginate.

In another aspect, the present invention also provides a method for degrading algin, which comprises the step of treating algin by using the algin lyase, gene, vector or strain.

In one embodiment, the temperature of the treatment is from 30 ℃ to 60 ℃, e.g., 35 ℃, 40 ℃, or 50 ℃; the pH is 5-11, e.g., pH6, 7, 8, 8.6, 9, 10 or 11.

In one embodiment, the salt concentration of the treatment is 10mM-5000mM, e.g., 1000mM, 2000mM, 2500mM, 3000mM, or 4000mM; preferably, the salt concentration is a NaCl concentration.

On the other hand, the invention also provides application of the algin lyase, the gene, the vector or the strain in inhibiting microbial biofilms. Preferably, the biological film is formed by taking algin as a matrix by microorganisms.

In another aspect, the invention also provides a preparation for inhibiting microbial biofilm, which comprises the algin lyase, the gene, the vector or the strain.

On the other hand, the invention also provides application of the algin lyase, the gene, the vector or the strain in preparation of a preparation for inhibiting a microbial biofilm.

In one embodiment, the microorganism is pseudomonas aeruginosa.

On the other hand, the invention also provides application of the algin lyase, the gene, the vector or the strain in inhibiting pseudomonas aeruginosa or preparation of a preparation for inhibiting pseudomonas aeruginosa.

In one embodiment, the invention also provides the use of the algin lyase, gene, vector or strain described above in the preparation of a medicament for treating or alleviating a disease caused by pseudomonas aeruginosa.

In another aspect, the invention also provides a method for treating a pseudomonas aeruginosa biological membrane, which comprises the step of treating the biological membrane by utilizing the algin lyase, the gene, the vector or the strain.

Drawings

FIG. 1 shows expression and purification of rAlyI1. (A) detection of algin lyase Activity. (1) purifying the protein, (2) inducing the histone, (3) empty vector control, (4) non-inducing control; (B) recombinant rAlyI1 expression and purified SDS-PAGE analysis. Lane M, protein markers; lane 1, recombinant protein; lane 2, purified rAlyI1.

FIG. 2 shows the biochemical characteristics of rAlyI1. (A) relative activity of rAlyI1 at different temperatures (4-70 ℃). Thermal stability of (B) rAlyI1. (C) optimal reaction pH. (D) pH stability. (E) influence of metal ions. (F) influence of NaCl. Data are shown as mean ± standard deviation, n=3.

FIG. 3 is an analysis of substrate specificity and end product. (A) substrate specificity of rAlyI1. (B) final product of TLC analysis. Lanes 1-3, purified mono-, di-, and trisaccharide standards; lanes 4-6, degradation products of algin, PM, PG. (C) Enzyme hydrolysates were subjected to ESI-MS analysis for 24 hours using algin as substrate. The DP2 and DP3 peaks represent disaccharides and trisaccharides, respectively. DP2 disaccharide m/z375 and DP3 (trisaccharide m/z 527+Na+ -H: m/z 549).

FIG. 4 shows the effect of alginate lyase rAlyI1 on the biofilm produced by Pseudomonas aeruginosa. (A) prevention of rAlyI1 biofilm formation. (B) biological membrane disruption Activity of rAlyI1. (C) Blank controls inhibiting biofilm formation after crystal violet staining. (D) after crystal violet staining rAlyI1 inhibits biofilm formation. (E) a blank to destroy the biofilm after crystal violet staining. (F) after crystal violet staining rAlyI1 destroyed the biofilm.

Detailed Description

The present invention is further described in terms of the following examples, which are given by way of illustration only, and not by way of limitation, of the present invention, and any person skilled in the art may make any modifications to the equivalent examples using the teachings disclosed above. Any simple modification or equivalent variation of the following embodiments according to the technical substance of the present invention falls within the scope of the present invention.

Example 1 materials and methods

1.1 strains, plasmids and reagents

Tamlanasp.I1 was isolated from Willebrand beach soft-shelled turtle and stored in the laboratory, and the alyI1 gene was cloned from the strain Tamlanasp.I1. Genomic DNA of rALYI1 strain was sequenced and stored in GenBank database, genBank number PRGAN656350. Gene cloning was performed using E.coli DH 5. Alpha. And the vector pUC19 (Sangon Biotech, shanghai, china). Protein expression was performed using E.coli BL21 (DE 3) (Beijing Sorbobo, china) and vector pRSFDuet-1 (Invitrogen, U.S.). Coli strains were grown in Luria-Bertani (LB) medium. Sodium alginate (M/G ratio: 1.66), purchased from Qingdao open moon seaweed group Co., ltd (Qingdao China). Standard algin monosaccharides, disaccharides, trisaccharides, tetrasaccharides, poly G (M/G ratio 1.8/98.2, purity: 99%) and poly M (M/G ratio 97.3/2.7, purity: 99%) were purchased from peninsula BZ Oligo biotechnology ltd (peninsula, china). Other chemicals and reagents used in this study were of analytical grade. Unless otherwise indicated, the other reagents are all analytical grade or higher grade reagents and are all commercially available.

1.2 Cloning, expression and purification of rALYI1

Primers alyI1-F (5' -TACTCA) containing BamHI and HindIII restriction sites, respectively (underlined), were usedGGATCCGACACAATCGAAG-3 ') and alyI1-R (5' -TACTCA)AAGCTTTAAAAATGTTCCGTCT-3') amplifying algin lyase gene alyI1, the nucleic acid sequence of the gene is shown as SEQ ID No.1, and the amino acid sequence encoded by the gene is shown as SEQ ID No. 2. After digestion of the PCR fragment with BamH I and HindIII, the purified fragment was cloned into pRSFDuet-1 expression vector and finally transformed into E.coli BL21 (DE 3). Recombinant cells carrying pRSFDuet-1-alyI1 were grown in Luria-Bertani medium supplemented with kanamycin (50. Mu.g/mL) at 37℃and 180rpm until OD at 600nm reached around 0.6, and then induced with isopropyl-1-thio-. Beta. -D-galactoside (IPTG) at a final concentration of 1mM at 20℃and 110rpm for 20h. Cells were then harvested by centrifugation at 4℃and 8000rpm for 10min, resuspended in 50mM phosphate buffer (0 at 12,000rpm for 10min at 4 ℃) and the supernatant loaded onto a nickel-nitrilotriacetic acid (Ni-IDA) affinity column (Sangon Biotech, shanghai, china.) purified fractions were collected, desalted using an economic Biotech membrane (Sangon Biotech, shanghai, china) and further analyzed using a 10% SDS-PAGE system (Bio-Rad, hercules, calif., USA)ker was purchased from Takara (Beijing, china). Protein concentration was determined using Bradford method. (Bradford 1976) Bovine Serum Albumin (BSA) was used as a control.

In order to rapidly and sensitively identify the activity of algin lyase, gram staining was improved (Sawant et al 2015). 0.9% agarose gel containing 1.0% alginate was stained with a quadruple diluted gram iodine solution after 3 hours of alginate incubation. Transparent circles around the algin lyase are evident within 1-2min after submerging the agarose gel.

1.3 rALYI1 purity analysis

For functional annotation of predicted proteins, the BLAST algorithm was used on the national center for Biotechnology information server (NCBI) for similarity searches of amino acid sequences (http:// www.ncbi.nlm.nih.gov). The molecular weight of the putative protein was estimated using peptide mass tools on the ExPASy server of Switzerland Bioinformatics institute (http:// swissmodel. ExPASy /). The theoretical pI of ALYI1 was calculated using the calculation pI tool (https:// web. Expasy. Org/computer_pI /). The signal peptide cleavage site of rALYI1 was predicted by the SignalP 5.0 server (http:// www.CBS.dtu.dk/services/Signalpp /). Multiple sequence alignment was performed using DNAMAN version (Lynnonbiosoft, san Ramon, CA, USA). Phylogenetic analysis used MEGA version 7.0 (Kumar et al 2016).

1.4 enzyme Activity assay

The activity of alginate lyase was determined by 3, 5-dinitrosalicylic acid (DNS) colorimetry (Miller 1959). One unit (U) of enzyme activity is defined as the amount of enzyme required to release 1mol of reducing sugar per minute. Unless otherwise indicated, the buffer (20 mM Na ₂ HPO ₄ -NaH ₂ PO ₄ pH 8.0), 100. Mu.L of alginate substrate (10 mg/mL) and 20. Mu.L of enzyme extract were assayed at 35℃for 30min, in parallel with three controls. Then, 300. Mu.L of a 3, 5-Dinitrosalicylate (DNS) solution was added to the solution. After incubation, the mixture was boiled for 5 minutes to terminate the reaction. Finally, absorbance was measured at 540 nm.

1.5 Characterization of rALYI1

1.5.1 Effect of temperature on enzyme Activity

The optimal temperature of the algin lyase is determined to be 4-60 ℃. The thermal stability of algin lyase was examined at 4℃at 10℃at 20℃at 25℃at 37℃at 40℃at 45℃at 50℃at 60℃at 70℃for 1 hour. The residual activity of the enzyme was determined by the standard method described above. Untreated enzyme activity was defined as 100%.

1.5.2 Influence of pH on enzyme Activity

The optimal pH of the algin lyase was examined by measuring the enzyme activity in the pH range of 5.0 to 12.0. The buffer system used was Na ₂ HPO ₄ Citric acid (pH 5.0-6.6), na ₂ HPO ₄ -NaH ₂ PO ₄ (pH 6.6-7.6), tris-HCl buffer (pH 7.6-8.6) and glycine-NaOH buffer (pH 8.6-12.0). 0.5% (w/v) sodium alginate was used as substrate and reacted in a suitable buffer at 40℃for 30min. pH stability detection, namely placing enzymes in buffer solutions with different pH values (5.0-12.0), standing at 4 ℃ for 1h, and measuring the residual enzyme activity. Untreated enzyme activity was defined as 100%.

1.5.3 influence of Metal ions, sodium chloride on enzyme Activity

By adding various metal ions at a final concentration of 1.0mM (NaCl, KCl, mgCl ₂ 、CaCl ₂ 、NH ₄ Cl、NiCl ₂ 、ZnCl ₂ 、SrCl ₂ 、MnCl ₂ 、FeCl ₃ And FeSO ₄ ) And the effect of different concentrations of NaCl (1, 10, 50, 100, 300, 500, 700, 900, 1000, 1500, 2000, 2500, 3000, 3500) on the enzyme activity was measured, and the enzyme solution was added to the substrate mixture to initiate the reaction, which was carried out at 40℃for 30min. The residual activity was then determined. The activity of the enzyme without added metal ions was defined as 100%.

1.6 Substrate specificity, degradation products and kinetic parameters of rALYI1

In this study, enzyme activity was determined by the DNS method described above using 1% (w/v) substrate solution (20 mM na2hpo 4-nah 2po 4, pH 8.0) and three polymers (sodium alginate, polyM and polyG) to evaluate the preferred substrate for rALYI1. To determine the oligosaccharide composition of the final digest, 30. Mu.L of diluting enzyme (5M) was added to 170. Mu.L of substrate solution containing 02% (w/v) substrate, 20mM Na ₂ HPO ₄ -NaH ₂ PO ₄ Buffer and 200mM NaCl (pH 7.0). After incubation at 35℃for 0.5, 12h, the reaction buffer was boiled for 5min and thin layer chromatography was performed with a solvent system (1-butanol/acetic acid/water 2:1:1). The thin layer chromatography plate was sprayed with sulfuric acid/ethanol reagent (1:4, v/v) and heated at 85℃for 5min.

Since algin is a polymer composed of a random combination of mannuronic acid and guluronic acid residues, the kinetic parameters of purified enzyme on algin and polyM were determined by measuring enzyme activity at different concentrations (0.1-8.0 mg/mL) of substrate. Since the Molecular Weights (MW) of the two are the same, MW (176 g/mol) of each monomer of uronic acid in the polymer is used to calculate the substrate molar concentration. Using 6150M ^-1 cm ^-1 The product concentration was determined by monitoring the increase in absorbance at 235 nm. The velocity (V) at the test substrate concentration is calculated as V (mol/s) = (milliAU/min. Times.min/60 s. Times.AU/1000 milliAU. Times.1 cm)/(6150M) ^-1 cm ^-1 )×(2×10 ^-4 L). Km and Vmax values were calculated by hyperbolic regression analysis as previously described (Swift et al 2014). Furthermore, by the ratio of Vmax to enzyme concentration ([ E)]) The turnover number (Kcat) of the enzyme was calculated. Kinetic parameters of rAlyI1 to algin were determined by measuring the initial rates of enzyme activity at different sodium alginate concentrations and calculated using Prism 6.0 (GraphPad Software, inc., la Jolla, CA, USA) according to the nonlinear regression fit of the Michaelis-Menten equation.

1.7 formation and removal of biofilm

In order to detect the effect of enzyme on biological membrane, pseudomonas aeruginosa is used as model bacteria in the study. The strain was stored in Trypsin Soybean Broth (TSB) containing 10% glycerol at-20 ℃. Pre-incubation was performed on TSA at 37℃for 24h. Individual colonies were incubated overnight at TSB 37 ℃. For biofilm analysis, pseudomonas aeruginosa was cultured in TSB medium at 37℃for 18h and the bacterial suspension was measured at OD ₆₀₀ Absorbance at. Next, the bacterial solution was diluted to 0.2OD using TSB medium ₆₀₀ And 100. Mu.L of the bacterial solution was placed in the wells of a 96-well plate. Furthermore, 100. Mu. Was added to the above-mentioned wellsL PBS and purified algin lyase. After 72 hours of incubation, the bacterial suspension was removed from the wells and washed three times in PBS as appropriate. Then, 100% methanol was added to fix the biofilm. After 15min incubation, the methanol was aspirated and washed 3 times with sterile PBS. Then, 200. Mu.L of 1% crystal violet was added to the wells after the biofilm had dried in air. After staining for 30min, wells were washed 3 times with PBS. After the biofilm was air-dried, 200 μl of 33% acetic acid was added and incubated at room temperature for 30min to dissolve the stained biofilm. Finally, absorbance values at 600nm were read using a microplate reader (BioTek Instruments, winioski, VT, USA). In addition, to observe the degradation of the biofilm formed by the enzyme on pseudomonas aeruginosa, the bacteria were cultured at 37 ℃ for 72 hours to form a biofilm. Then, 100. Mu.L of PBS, 100. Mu.L of purified rALYI1 used in the biofilm formation assay, or three parallel controls were added to the wells and incubated at 37℃for 24h. The following procedure was the same as in the biofilm inhibition assay described above.

Example 2 results and discussion

2.1 Sequence analysis of aly1

The marine bacterium Tamlanasp.I1 was isolated from Willebrand beach soft-shelled turtle. The algin can grow rapidly and efficiently in single carbon source of algin, and has high algin lyase activity. The open reading frame length of the gene alyI1 is 897bp, and 298 amino acids are encoded, including a signal peptide sequence deduced from SignalP. The deduced theoretical isoelectric point (pI) and theoretical molecular weight (Mw) of the ali 1 protein were 4.55 and 32.15kDa, respectively. The nucleic acid sequence of the lyase is shown as SEQ ID No.1, and the amino acid sequence of the lyase is shown as SEQ ID No. 2.

A BLAST-treated multiple sequence alignment shows that ALYI1 is a novel algin lyase in the PL7 family, with the highest identity (30.0%) to AlyA1-II of the endo-bifunctional algin lyase Sphingomonas sp.A 1. According to the CAZy database, the PL7 family has 6 subfamilies.

2.2 Expression, purification and characterization of rALYI1

The activity of rALYI1 algin lyase is detected by adopting a flat plate method and an ultraviolet absorption method. The results of the plate experiments showed that a transparent ring was formed after staining with gram iodine solution (fig. 1A), indicating that the enzyme had successfully achieved exogenous expression, and the recombinant protein proved to have algin lyase activity. The alyI1 gene was successfully cloned, expressed in E.coli BL21 (DE 3), and purified by NTA-Ni agarose gel affinity chromatography using His-tag. SDS-PAGE analysis showed that the purified protein appeared as a major band, close to the predicted 32kDa Mw (FIG. 1B).

The optimal temperature for rALYI1 was determined over a temperature range of 4℃to 70 ℃. As shown in FIG. 2A, the optimal temperature of the enzyme is 40℃and exhibits a relative activity exceeding 40% in the temperature range of 50 to 60 ℃. Little activity was observed at 70 ℃. The thermal stability of rALYI1 was studied by measuring residual activity after culturing the enzyme at 25, 30, 35, 40, 45 and 50℃for different times, respectively (FIG. 2B). After 1h of cultivation at 4-40 ℃, the algin lyase is relatively stable. Culturing at higher temperatures results in loss of enzyme activity. After incubation at 45℃for 0.5h and 1h, the enzyme retained 51% and 16% residual activity, respectively. Almost no activity was observed at 50℃for 30min. These results indicate that the enzyme has a relatively narrow range of thermostability.

The optimal pH of rALYI1 was examined at various pH values at 4 ℃. As shown in FIG. 2C, the enzyme activity was highest at pH8.6, but it is highlighted that at Na ₂ HPO ₄ Citric acid (pH 5.0-6.6), na ₂ HPO ₄ –NaH ₂ PO ₄ The enzyme activity in (pH 6.6-7.6), tris-HCl (pH 7.6-8.6) or glycine-NaOH (pH 8.0-11.0) remained unchanged and almost all of the activity was retained. No enzyme activity was detected at pH 12.0. At pH 11.0, the enzyme still had a relative activity of 51%. After incubation of algin lyase in a series of buffers of different pH values (5.0-11.0) for 1h at 4℃the pH stability was determined by measuring the residual activity (FIG. 2D). The results show that rALYI1 is stable over a wide pH range of 6.0-8.0, and retains over 70% of its original activity. The residual activity was maintained at 42% and 51% at pH5.0 and 11.0, respectively.

The final concentration of 1mM of each metal ion (Na ⁺ 、K ⁺ 、Mg ²⁺ 、Ca ²⁺ 、Mn ²⁺ 、Ni ²⁺ 、Zn ²⁺ 、Sr ²⁺ 、Fe ³⁺ 、Fe ²⁺ And NH ⁴⁺ ) The effect of metal ions on algin lyase activity was examined (FIG. 2E). K (K) ⁺ 、Ca ²⁺ 、Fe ³⁺ 、Fe ²⁺ 、NH ⁴⁺ Has an inhibitory effect on the enzyme, wherein Ca ²⁺ The effect of (2) is most prominent. Enzyme activity is not affected by Fe ²⁺ Is a function of (a) and (b). 1mM Na ⁺ Stimulating algin lyase activity. Further study of different concentrations of Na ⁺ Is shown (fig. 2F). When 1500mM NaCl was used, the activity of rALYI1 reached a maximum, and no significant change in enzyme activity occurred in the range of 3000 to 5000mM NaCl addition. Although the enzyme activity decreased rapidly before 5000mM NaCl was added, some enzyme activity was maintained in rALYI1. The results show that the highest activity (239% of the relative activity) was observed in the presence of 1500mM NaCl. Thus, rALYI1 can remain stable over a wide range of NaCl concentrations, possibly due to its initial origin in the marine environment.

2.3 analysis of substrate specificity and end products

By measuring the OD of unsaturated uronic acid ₂₃₅ The substrate specificity was studied in which unsaturated uronic acid is an oligomer produced by alpha-elimination reaction using algin, polyG and polyM as substrates. As shown in FIG. 3A, rALYI1 algin lyase exhibits activity on algin, polyG and polyM, and preferentially degrades algin rather than PM and PG.

To investigate the final product of rALYI1, the degradation products of algin, polyM and polyG after 24 hours were analyzed by Thin Layer Chromatography (TLC). The results of thin layer chromatography showed that disaccharides, trisaccharides are the main degradation products of polyM and algin (fig. 3B). In addition, disaccharides and trisaccharides were also detected by ESI-MS monitoring the identification of final depolymerization products of algin (FIG. 3C). The results are consistent with thin layer chromatography analysis. The lack of monomer products suggests that rALYI1 has an endo-action on algin, polyG and polyM.

The kinetic parameter values of rALYI1 are calculated by using sodium alginate with different concentrations (0.1-8 mg/mL) as substrates and using a Lineweaver-Bulk graph. Km (mg/mL) and Vmax(s) in sodium alginate ^-1 ) Value of1.23 and 4.14 respectively. Reaction constant kcat(s) ^-1 ) And a catalytic efficiency constant kcat/Km (mg ^-1 ml s ^-1 ) 221.78 and 180.31, respectively. The enzyme activity of alginate lyase rAlyI1 is 1298.68U/mg by taking alginate as a substrate.

2.4 Effect of algin lyase rALYI1 on Pseudomonas aeruginosa biofilm

The research adopts alginate lyase rALYI1 with higher enzyme activity to explore the influence of the alginate lyase rALYI1 on pseudomonas aeruginosa biomembrane. Purified rALYI1 and other control components were incubated with bacteria in 96-well plates for 36h and further examined by crystal violet staining to see if the algin lyase rALYI1 would affect biofilm formation by P.aeruginosa. The results indicate that rALYI1 inhibits P.aeruginosa biofilm formation compared to PBS and denatured rALYI1. As shown in FIG. 4A, it is notable that rALYI1 showed the highest inhibitory activity relative to biofilm formation at the temperature of culture. The biofilm formation of pseudomonas aeruginosa was reduced by 50.53% ± 3.52%. In addition, the interaction between the enzyme rALYI1 and the Pseudomonas aeruginosa biofilm was also observed using fluorescence inverted microscopy (FIGS. 4C, 4D). In addition, equivalent amounts of inactivated enzyme did not show significant inhibition compared to the control, indicating that rALYI1 with higher enzyme activity plays an important role in inhibiting P.aeruginosa biofilm formation. As previously mentioned, the composition of the bacterial biofilm and its external matrix may be responsible for inhibiting biofilm formation. The algin lyase can efficiently degrade algin serving as a matrix core component, and reduce the formation of a biological film.

To evaluate whether rALYI1 has the ability to eradicate the biofilm formed by Pseudomonas aeruginosa, the algin lyase group and the control group were cultured with the biofilm formed by Pseudomonas aeruginosa cultured for 48 hours, respectively. The results (FIG. 4B) show that rALYI1 was more degraded by the crystal violet-stained biofilm, and the degradation rate of P.aeruginosa was about 44.98% + -6.72%. In addition, the interaction between the enzyme rALYI1 and the Pseudomonas aeruginosa biofilm was also closely observed using fluorescence inverted microscopy (FIGS. 4E, 4F).

While the invention has been described in detail with respect to the general description and specific embodiments thereof, it will be apparent to those skilled in the art that various modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.

SEQUENCE LISTING

<110> university of Shandong

<120> an algin lyase ALyI1 and use thereof

<130> 11

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<170> PatentIn version 3.5

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<211> 897

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<220>

<223> AlyI1

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atgaaacatc tcctatttat attcttatta tgcagctcgg tattgttcaa ttgcagcaca 60

accaatgaag aagctgatca cacagtagaa caacccgaaa cagaaactga gactgagact 120

gagactgaga ctgaaaccga acctgaagaa gaagaaagta acatcatctg gaaaaactgg 180

tatttatctg ttcctattaa tagaggaaat ggcaaagcga cttctatatt ttatgaggcc 240

atagaaaaca acaaattaac cgctgctgaa tcggagtact tttataaaaa tgacgatggt 300

agctacacct ttttcaccag atttacagga tttaccactt ctggcgagta tccattaaat 360

gaaaaatatt gccgtacaga gcttcgagag ttttggaaag gcaaccaaac cactagcgat 420

aactggccaa tgagttcagg gactcacatt ttagagtcta caataaaagt agactatgta 480

gaaggcaatg gcagaactat tgtggcgcaa attcacggta ttgaaacccc tggttttgaa 540

ggcgcacctg ctacagttaa aatacgctgg aacagtggcg aaattcaaat agactattac 600

accaaacctg atagcggcga accttggacc agtgcttttg atgataaaat taatgtgggg 660

tatgtgggta acgacatttt tacttttaaa attaaaattg aaaatggtaa attctattat 720

gctctagttt gcgaagccaa aaatattaac atcgattata ctttaattta tgattatgta 780

ggtaatggtt atggtcacga taattacttt aaaacaggaa attattatgg ttggaatgcc 840

gattacgaaa aaacagctca agttatttta tacaaagtaa agacggaaca tttttaa 897

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<223> AlyI1

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Met Lys His Leu Leu Phe Ile Phe Leu Leu Cys Ser Ser Val Leu Phe

1 5 10 15

Asn Cys Ser Thr Thr Asn Glu Glu Ala Asp His Thr Val Glu Gln Pro

20 25 30

Glu Thr Glu Thr Glu Thr Glu Thr Glu Thr Glu Thr Glu Thr Glu Pro

35 40 45

Glu Glu Glu Glu Ser Asn Ile Ile Trp Lys Asn Trp Tyr Leu Ser Val

50 55 60

Pro Ile Asn Arg Gly Asn Gly Lys Ala Thr Ser Ile Phe Tyr Glu Ala

65 70 75 80

Ile Glu Asn Asn Lys Leu Thr Ala Ala Glu Ser Glu Tyr Phe Tyr Lys

85 90 95

Asn Asp Asp Gly Ser Tyr Thr Phe Phe Thr Arg Phe Thr Gly Phe Thr

100 105 110

Thr Ser Gly Glu Tyr Pro Leu Asn Glu Lys Tyr Cys Arg Thr Glu Leu

115 120 125

Arg Glu Phe Trp Lys Gly Asn Gln Thr Thr Ser Asp Asn Trp Pro Met

130 135 140

Ser Ser Gly Thr His Ile Leu Glu Ser Thr Ile Lys Val Asp Tyr Val

145 150 155 160

Glu Gly Asn Gly Arg Thr Ile Val Ala Gln Ile His Gly Ile Glu Thr

165 170 175

Pro Gly Phe Glu Gly Ala Pro Ala Thr Val Lys Ile Arg Trp Asn Ser

180 185 190

Gly Glu Ile Gln Ile Asp Tyr Tyr Thr Lys Pro Asp Ser Gly Glu Pro

195 200 205

Trp Thr Ser Ala Phe Asp Asp Lys Ile Asn Val Gly Tyr Val Gly Asn

210 215 220

Asp Ile Phe Thr Phe Lys Ile Lys Ile Glu Asn Gly Lys Phe Tyr Tyr

225 230 235 240

Ala Leu Val Cys Glu Ala Lys Asn Ile Asn Ile Asp Tyr Thr Leu Ile

245 250 255

Tyr Asp Tyr Val Gly Asn Gly Tyr Gly His Asp Asn Tyr Phe Lys Thr

260 265 270

Gly Asn Tyr Tyr Gly Trp Asn Ala Asp Tyr Glu Lys Thr Ala Gln Val

275 280 285

Ile Leu Tyr Lys Val Lys Thr Glu His Phe

290 295

Claims

1. A method for degrading algin, the method comprising the step of treating alginate with algin lyase, or a gene encoding the algin lyase, or a recombinant vector comprising the gene, or a recombinant strain comprising the recombinant vector, wherein the amino acid sequence of the algin lyase is shown in SEQ ID No.2, the treatment temperature is 30-60 ℃, the treatment pH is 5-11, and the salt concentration of the treatment is 10mM-5000mM.

2. A method for treating a pseudomonas aeruginosa biofilm, said method being for non-disease therapeutic purposes, said method comprising the step of treating said biofilm with an algin lyase, or a gene encoding said algin lyase, or a recombinant vector comprising said gene, or a recombinant strain comprising said recombinant vector, characterized in that the amino acid sequence of said algin lyase is shown in SEQ ID No.2, the treatment temperature is 30-60 ℃, the pH of said treatment is 5-11, and the salt concentration of said treatment is 10mM-5000mM.

3. The method according to claim 1 or 2, wherein the salt concentration of the treatment is 1000mM-3000mM.

4. A method according to claim 3, wherein the salt concentration of the treatment is 1500mM.