Reconstruction of a robust bacterial replication module.

Chromosomal DNA replication is a fundamental process of life, involving the assembly of complex machinery and dynamic regulation. In this study, we reconstructed a bacterial replication module (pRC) by artificially clustering 23 genes involved in DNA replication and sequentially deleting these genes from their naturally scattered loci on the chromosome of Escherichia coli. The integration of pRC into the chromosome, moving from positions farther away to close to the replication origin, leads to an enhanced efficiency in DNA synthesis, varying from lower to higher. Strains containing replication modules exhibited increased DNA replication by accelerating the replication fork movement and initiating chromosomal replication earlier in the replication cycle. The minimized module pRC16, containing only replisome and elongation encoding genes, exhibited chromosomal DNA replication efficiency comparable to that of pRC. The replication module demonstrated robust and rapid DNA replication, regardless of growth conditions. Moreover, the replication module is plug-and-play, and integrating it into Mb-sized extrachromosomal plasmids improves their genetic stability. Our findings indicate that DNA replication, being a fundamental life process, can be artificially reconstructed into replication functional modules. This suggests potential applications in DNA replication and the construction of synthetic modular genomes.

Creating a functional single-chromosome yeast.

Eukaryotic genomes are generally organized in multiple chromosomes. Here we have created a functional single-chromosome yeast from a Saccharomyces cerevisiae haploid cell containing sixteen linear chromosomes, by successive end-to-end chromosome fusions and centromere deletions. The fusion of sixteen native linear chromosomes into a single chromosome results in marked changes to the global three-dimensional structure of the chromosome due to the loss of all centromere-associated inter-chromosomal interactions, most telomere-associated inter-chromosomal interactions and 67.4% of intra-chromosomal interactions. However, the single-chromosome and wild-type yeast cells have nearly identical transcriptome and similar phenome profiles. The giant single chromosome can support cell life, although this strain shows reduced growth across environments, competitiveness, gamete production and viability. This synthetic biology study demonstrates an approach to exploration of eukaryote evolution with respect to chromosome structure and function.

Endovascular Embolization and Atorvastatin Therapy for Recurrent Chronic Subdural Hematoma.

Recurrent chronic subdural hematoma poses a significant clinical challenge. While craniotomy effectively removes the hematoma membrane, it is an invasive procedure associated with significant trauma. Recently, endovascular embolization of the middle meningeal artery has emerged as a promising minimally invasive alternative, demonstrating efficacy and a low recurrence rate in treating chronic subdural hematoma. Furthermore, postoperative administration of oral atorvastatin calcium may enhance hematoma absorption, thereby improving patient outcomes during the early recovery phase.

Epithelial salivary gland tumors: Utility of radiomics analysis based on diffusion-weighted imaging for differentiation of benign from malignant tumors.

OBJECTIVE: To evaluate the utility of radiomics analysis for differentiating benign and malignant epithelial salivary gland tumors on diffusion-weighted imaging (DWI). METHODS: A retrospective dataset involving 218 and 51 patients with histology-confirmed benign and malignant epithelial salivary gland tumors was used in this study. A total of 396 radiomic features were extracted from the DW images. Analysis of variance (ANOVA) and least-absolute shrinkage and selection operator regression (LASSO) were used to select optimal radiomic features. The selected features were used to build three classification models namely, logistic regression method (LR), support vector machine (SVM), and K-nearest neighbor (KNN) by using a five-fold cross validation strategy on the training dataset. The diagnostic performance of each classification model was quantified by receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) in the training and validation datasets. RESULTS: Eight most valuable features were selected by LASSO. LR and SVM models yielded optimally diagnostic performance. In the training dataset, LR and SVM yielded AUC values of 0.886 and 0.893 via five-fold cross validation, respectively, while KNN model showed relatively lower AUC (0.796). In the testing dataset, a similar result was found, where AUC values for LR, SVM, and KNN were 0.876, 0.870, and 0.791, respectively. CONCLUSIONS: Classification models based on optimally selected radiomics features computed from DW images present a promising predictive value in distinguishing benign and malignant epithelial salivary gland tumors and thus have potential to be used for preoperative auxiliary diagnosis.

CasHRA (Cas9-facilitated Homologous Recombination Assembly) method of constructing megabase-sized DNA.

Current DNA assembly methods for preparing highly purified linear subassemblies require complex and time-consuming in vitro manipulations that hinder their ability to construct megabase-sized DNAs (e.g. synthetic genomes). We have developed a new method designated 'CasHRA (Cas9-facilitated Homologous Recombination Assembly)' that directly uses large circular DNAs in a one-step in vivo assembly process. The large circular DNAs are co-introduced into Saccharomyces cerevisiae by protoplast fusion, and they are cleaved by RNA-guided Cas9 nuclease to release the linear DNA segments for subsequent assembly by the endogenous homologous recombination system. The CasHRA method allows efficient assembly of multiple large DNA segments in vivo; thus, this approach should be useful in the last stage of genome construction. As a proof of concept, we combined CasHRA with an upstream assembly method (Gibson procedure of genome assembly) and successfully constructed a 1.03 Mb MGE-syn1.0 (Minimal Genome of Escherichia coli) that contained 449 essential genes and 267 important growth genes. We expect that CasHRA will be widely used in megabase-sized genome constructions.

Multiple biological defects caused by calycosin-7-O-ß-d-glucoside in the nematode Caenorhabditis elegans are associated with the activation of oxidative damage.

Calycosin-7-O-ß-d-glucoside (CG) is an important active isoflavone compound in Radix Astragali that has many bioactivities. However, the toxicological effects and related toxicological mechanism of CG have been rarely documented. The purpose of the present study was to evaluate the toxicity effects of CG on the model organism Caenorhabditis elegans. Some characteristics of the nematode, including lifespan, movement behavior and reproductive capacity, were used to detect the toxic effects of CG on C. elegans. The results showed that CG could shorten the lifespan of C. elegans by up to 25.3% and severely damage the movement of N2 larvae compared with the control group. Moreover, CG could prolong the generation times and reduce the brood sizes. Furthermore, CG promoted the formation of reactive oxygen species (ROS), which caused oxidative stress, increased the mRNA expression of sod-1, sod-2, sod-3, sod-5, ctl-1, ctl-2 and ctl-3, and induced the antioxidant enzymes activities of superoxide dismutase and catalase to scavenge free radicals. However, antioxidant treatment experiments showed that Trolox could reduce the level of ROS caused by CG to the normal state of the control. These results suggested that the generation and elimination of ROS could not restore normal homeostasis in C. elegans treated by CG. These findings indicated that the activation of oxidative damage is one of the most important toxic mechanisms of CG in C. elegans.

Deubiquitylating Enzyme OTUB1 Facilitates Neuronal Survival After Intracerebral Hemorrhage Via Inhibiting NF-κB-triggered Apoptotic Cascades.

The deubiquitylase OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1) has been implicated in the pathogenesis of various human diseases. However, the molecular mechanism by which OTUB1 participates in the pathogenesis of intracerebral hemorrhage (ICH) remains elusive. In the present study, we established an autologous whole blood fusion-induced ICH model in C57BL/6 J mice. We showed that the upregulation of OTUB1 contributes to the attenuation of Nuclear factor kappa B (NF-κB) and its downstream apoptotic signaling after ICH. OTUB1 directly associates with NF-κB precursors p105 and p100 after ICH, leading to attenuated polyubiquitylation of p105 and p100. Moreover, we revealed that NF-κB signaling was modestly activated both in ICH tissues and hemin-exposed HT-22 neuronal cells, accompanied with the activation of NF-κB downstream pro-apoptotic signaling. Notably, overexpression of OTUB1 strongly inhibited hemin-induced NF-κB activation, whereas interference of OTUB1 led to the opposite effect. Finally, we revealed that lentiviral transduction of OTUB1 markedly ameliorated hemin-induced apoptotic signaling and HT-22 neuronal death. Collectively, these findings suggest that the upregulation of OTUB1 serves as a neuroprotective mechanism in antagonizing neuroinflammation-induced NF-κB signaling and neuronal death, shed new light on manipulating intracellular deubiquitylating pathways as novel interventive approaches against ICH-induced secondary neuronal damage and death.

Effect of different concentrations of sufentanil combined with ropivacaine on epidural fever during labor: A single-center retrospective study.

Labor epidural analgesia (LEA) is associated with increased maternal body temperature; however, the responsible mechanism is unknown. Recent studies suggest that changes in EA affect the incidence of fever and that epidural sufentanil supplementation enhances analgesia and reduces the amount of local anesthetic. The aim of this study was to evaluate the effect of different concentrations of sufentanil combined with ropivacaine on intrapartum fever during delivery. We performed a retrospective study comparing maternal fever rates in patients receiving labor analgesia between December 2018 and January 2019. Each patient receiving different concentrations of sufentanil in their EA received either proposal H (0.08% ropivacaine + 0.4 µg/mL sufentanil) or proposal L (0.08% ropivacaine + 0.2 µg/mL sufentanil), with the same nulliparous status. The primary outcome of this study was the incidence of intrapartum maternal fever, which was defined as any temperature ≥ 38°C during labor using Fisher exact test. Secondary outcome measures included visual analog scale (VAS) pain scores, birth events, and neonatal outcomes. We observed a perinatal fever incidence rate of 11.7% in the group receiving proposal L, while the incidence rate was 19.8% in the group receiving proposal H (P = .001). Five hours after administration, the average body temperature of the puerpera decreased significantly in the proposal L group compared with proposal H group. In addition, treatment with 0.2 µg/mL sufentanil provided satisfactory pain relief during labor, shortened the first stage of labor and total labor time, reduced oxytocin use, and had no significant adverse effects on neonatal outcomes. EA may increase the risk of intrapartum epidural-associated fever. Compared with the 0.4 µg/mL sufentanil group, the 0.2 µg/mL sufentanil group can provide better analgesia and improve maternal fever. These retrospective results highlighted the importance of prospective and mechanistic studies of maternal fever associated with intraspinal analgesia.

Application of buried auricular point combined with Wenjing Sanhan prescription in arteriosclerosis obliterans patients with resting pain.

BACKGROUND: Research on the combined use of ear acupoint embedding beans and warming meridians with cold-dispersing formulas for alleviating resting pain in patients with arteriosclerosis obliterans (ASO) remains limited. AIM: To explore the therapeutic efficacy of auricular point embedding beans combined with Wenjing Sanhan prescription in alleviating resting pain in patients with lower-limb ASO. METHODS: A total of 100 patients with ASO experiencing resting pain who were treated at our hospital from January 2022 to January 2023 were enrolled. They were randomly allocated into two groups using a double-blind approach. The control group was treated using a warming meridian with a cold-dispersing formula, while the study group received additional treatment with ear acupoint embedding beans. The clinical efficacy, ankle-brachial artery pressure ratio, hemorheological indicators, and traditional Chinese medicine symptom scores were compared between the two groups. RESULTS: The clinical efficacy rate in the study group was significantly higher (94.00%) than that in the control group (72.00%, P < 0.05). Moreover, the ankle-brachial artery pressure ratio was significantly higher in the study group after treatment (P < 0.05). Hemorheological parameters, including whole blood viscosity, plasma viscosity (1.83 ± 0.11) mPa/s, fibrinogen levels (3.30 ± 0.21) g/L, platelet adhesion rate (49.87% ± 10.51%), and erythrocyte aggregation index (1.79 ± 0) were improved in the study group compared to the control group. In addition, the scores for decreased skin temperature (1.41 ± 0.26), intermittent claudication (1.30 ± 0.20), and resting pain (1.23 ± 0.31) were significantly lower in the study group than those in the control group (all P < 0.05). The level of oxidative stress in the study group also exhibited significant improvement (P < 0.05), and the levels of inflammatory factors were considerably lower than those in the control group. CONCLUSION: The combination of ear point embedding beans and Wenjing Sanhan prescription demonstrates promising clinical efficacy in alleviating resting pain associated with ASO.

Metformin dampens the progression of cholangiofibrosis induced by thioacetamide using deep learning.

Purpose: The consistent use of metformin has been linked to a reduced incidence of neoplastic diseases among diabetic populations. As a preventive intervention, metformin may offer a more favorable risk-benefit profile. Here, we explored the efficacy of metformin in the primary prevention of cholangiofibrosis, which can precede the carcinogen-induced development of cholangiocarcinoma (CCA). Our objective was to assess the potential of metformin to act as an intervention prior to the onset of these conditions. Methods: A rat model of thioacetamide (TAA)-induced cholangiofibrosis was utilized to assess the impact of metformin on the induction process of cholangiocarcinoma (CCA). Liver tissues were harvested and analyzed histologically using light microscopy, complemented by a deep-learning convolutional neural network for enhanced evaluation. Additionally, RNA sequencing (RNA-seq) was performed to investigate the genetic alterations associated with metformin treatment in this TAA-induced cholangiofibrosis model. Results: In the rat model, the TAA control group exhibited an increased incidence and average count of cholangiofibrosis cases in the liver, with rates of 100 % and an average of 12.0, compared to the metformin-treated group, which showed an incidence of 70 % and an average of 3.3. Notably, the progression from normal cholangioles to cholangiofibrosis was associated with the upregulation of several proteins critical for metabolic processes and the tumor microenvironment. These alterations were significantly mitigated by metformin treatment. Conclusions: Long-term metformin use may offer protective benefits against cholangiofibrosis, partially by regulating metabolic processes and improving the tumor microenvironment.

Comparative analysis of gene ontology-based semantic similarity measurements for the application of identifying essential proteins.

Identifying key proteins from protein-protein interaction (PPI) networks is one of the most fundamental and important tasks for computational biologists. However, the protein interactions obtained by high-throughput technology are characterized by a high false positive rate, which severely hinders the prediction accuracy of the current computational methods. In this paper, we propose a novel strategy to identify key proteins by constructing reliable PPI networks. Five Gene Ontology (GO)-based semantic similarity measurements (Jiang, Lin, Rel, Resnik, and Wang) are used to calculate the confidence scores for protein pairs under three annotation terms (Molecular function (MF), Biological process (BP), and Cellular component (CC)). The protein pairs with low similarity values are assumed to be low-confidence links, and the refined PPI networks are constructed by filtering the low-confidence links. Six topology-based centrality methods (the BC, DC, EC, NC, SC, and aveNC) are applied to test the performance of the measurements under the original network and refined network. We systematically compare the performance of the five semantic similarity metrics with the three GO annotation terms on four benchmark datasets, and the simulation results show that the performance of these centrality methods under refined PPI networks is relatively better than that under the original networks. Resnik with a BP annotation term performs best among all five metrics with the three annotation terms. These findings suggest the importance of semantic similarity metrics in measuring the reliability of the links between proteins and highlight the Resnik metric with the BP annotation term as a favourable choice.

The global impact of the delta subunit RpoE of the RNA polymerase on the proteome of Streptococcus mutans.

Transcriptional specificity in low-G+C Gram-positive bacteria is maintained by RpoE, the delta subunit of the RNA polymerase. Here, we studied the effect of RpoE at the proteome level in the human dental pathogen Streptococcus mutans by comparing the ΔrpoE mutant with the wild-type under five conditions: (0) exponential growth, (1) early stationary phase, (2) acid stress, (3) oxidative stress, and (4) combined acid and oxidative stress. A total of 280 cellular protein spots were reproducibly detected, of which 97 differentially expressed protein spots were identified by MALDI-TOF MS. Lack of RpoE caused downregulation of proteins for carbohydrate metabolism and energy production, including phosphoglucomutase (PGM), the phosphopentomutase DeoB and the pyruvate formate-lyase Pfl. The ΔrpoE mutant had extensive changes in the abundance of proteins involved in acid and oxidative tolerance and protein turnover, and of chaperones, at exponential phase in the absence of stress, suggesting a potential internal stress. In addition, the mutant had reduced amounts of proteins for adaptation responses, e.g. the multiple sugar transport and metabolism enzymes required for entering early stationary phase, and the proteins for stress-defence mechanisms and glycolysis under oxidative stress. Comparison of the proteome data with the corresponding transcriptome data suggested that the effects were the result of altered transcriptional and post-transcriptional regulation. The data are consistent with the reduced transcriptional specificity of the RNA polymerase in the ΔrpoE mutant, and suggest a general impact, but not a specific regulatory role, of RpoE in stress adaptation.

NMFLRR: Clustering scRNA-Seq Data by Integrating Nonnegative Matrix Factorization With Low Rank Representation.

Fast-developing single-cell technologies create unprecedented opportunities to reveal cell heterogeneity and diversity. Accurate classification of single cells is a critical prerequisite for recovering the mechanisms of heterogeneity. However, the scRNA-seq profiles we obtained at present have high dimensionality, sparsity, and noise, which pose challenges for existing clustering methods in grouping cells that belong to the same subpopulation based on transcriptomic profiles. Although many computational methods have been proposed developing novel and effective computational methods to accurately identify cell types remains a considerable challenge. We present a new computational framework to identify cell types by integrating low-rank representation (LRR) and nonnegative matrix factorization (NMF); this framework is named NMFLRR. The LRR captures the global properties of original data by using nuclear norms, and a locality constrained graph regularization term is introduced to characterize the data's local geometric information. The similarity matrix and low-dimensional features of data can be simultaneously obtained by applying the alternating direction method of multipliers (ADMM) algorithm to handle each variable alternatively in an iterative way. We finally obtained the predicted cell types by using a spectral algorithm based on the optimized similarity matrix. Nine real scRNA-seq datasets were used to test the performance of NMFLRR and fifteen other competitive methods, and the accuracy and robustness of the simulation results suggest the NMFLRR is a promising algorithm for the classification of single cells. The simulation code is freely available at: https://github.com/wzhangwhu/NMFLRR_code.

CEGSO: Boosting Essential Proteins Prediction by Integrating Protein Complex, Gene Expression, Gene Ontology, Subcellular Localization and Orthology Information.

Essential proteins are assumed to be an indispensable element in sustaining normal physiological function and crucial to drug design and disease diagnosis. The discovery of essential proteins is of great importance in revealing the molecular mechanisms and biological processes. Owing to the tedious biological experiment, many numerical methods have been developed to discover key proteins by mining the features of the high throughput data. Appropriate integration of differential biological information based on protein-protein interaction (PPI) network has been proven useful in predicting essential proteins. The main intention of this research is to provide a comprehensive study and a review on identifying essential proteins by integrating multi-source data and provide guidance for researchers. Detailed analysis and comparison of current essential protein prediction algorithms have been carried out and tested on benchmark PPI networks. In addition, based on the previous method TEGS (short for the network Topology, gene Expression, Gene ontology, and Subcellular localization), we improve the performance of predicting essential proteins by incorporating known protein complex information, the gene expression profile, Gene Ontology (GO) terms information, subcellular localization information, and protein's orthology data into the PPI network, named CEGSO. The simulation results show that CEGSO achieves more accurate and robust results than other compared methods under different test datasets with various evaluation measurements.

Astragaloside IV Extends Lifespan of Caenorhabditis elegans by Improving Age-Related Functional Declines and Triggering Antioxidant Responses.

Astragaloside IV (AS-IV) is a representative component of astragaloside saponins in dried roots of Astragali Radix. Astragaloside possesses a broad spectrum of pharmacological activities, including antibacterial, anti-fibrosis, antioxidant, anti-inflammatory, and neuroprotective effects. However, the role of AS-IV in antiaging remains unclear. In this article, we studied the function of AS-IV in antiaging by using the Caenorhabditis elegans (C. elegans) model. We showed that AS-IV can prolong the lifespan of C. elegans in a natural aging model, a paraquat injury model, and a heat stress model and improve the movement capacity of nematodes. 1H-NMR data indicate an improvement of glutamate content and a decrease in glucose in the AS-IV treatment group compared with the control. Further investigation revealed that AS-IV can induce the mRNA expression of superoxide dismutase (SOD) and catalase (CAT) genes and increase the activities of SOD and CAT in the nematode. Interestingly, AS-IV could not extend the lifespan of sod-1, sod-2, sod-3, sod-4, sod-5, ctl-1, ctl-2, ctl-3, and daf-16 mutants. These data indicate that AS-IV prevents aging via mainly improving age-related functional declines, the antioxidant capacity of nematodes and partially modulating the insulin/insulin growth factor 1 signaling pathway activity. Our results provide new insights into how AS-IV prevents and treats aging.

The delta subunit of RNA polymerase, RpoE, is a global modulator of Streptococcus mutans environmental adaptation.

The delta subunit of RNA polymerase, RpoE, is widespread in low-G+C Gram-positive bacteria and is thought to play a role in enhancing transcriptional specificity by blocking RNA polymerase binding at weak promoter sites and stimulating RNA synthesis by accelerating core enzyme recycling. Despite the well-studied biochemical properties of RpoE, a role for this protein in vivo has not been defined in depth. In this study, we show that inactivation of rpoE in the human dental caries pathogen Streptococcus mutans causes impaired growth and loss of important virulence traits, including biofilm formation, resistance to antibiotics, and tolerance to environmental stresses. Complementation of the mutant with rpoE expressed in trans restored its phenotype to wild type. The luciferase fusion reporter showed that rpoE was highly transcribed throughout growth and that acid and hydrogen peroxide stresses repressed rpoE expression. Transcriptome profiling of wild-type and ΔrpoE cells in the exponential and early stationary phase of growth, under acid and hydrogen peroxide stress and under both stresses combined, revealed that genes involved in histidine synthesis, malolactic fermentation, biofilm formation, and antibiotic resistance were downregulated in the ΔrpoE mutant under all conditions. Moreover, the loss of RpoE resulted in dramatic changes in transport and metabolism of carbohydrates and amino acids. Interestingly, differential expression, mostly upregulation, of 330 noncoding regions was found. In conclusion, this study demonstrates that RpoE is an important global modulator of gene expression in S. mutans which is required for optimal growth and environmental adaptation.

Cdc13 is predominant over Stn1 and Ten1 in preventing chromosome end fusions.

Telomeres define the natural ends of eukaryotic chromosomes and are crucial for chromosomal stability. The budding yeast Cdc13, Stn1 and Ten1 proteins form a heterotrimeric complex, and the inactivation of any of its subunits leads to a uniformly lethal phenotype due to telomere deprotection. Although Cdc13, Stn1 and Ten1 seem to belong to an epistasis group, it remains unclear whether they function differently in telomere protection. Here, we employed the single-linear-chromosome yeast SY14, and surprisingly found that the deletion of CDC13 leads to telomere erosion and intrachromosome end-to-end fusion, which depends on Rad52 but not Yku. Interestingly, the emergence frequency of survivors in the SY14 cdc13Δ mutant was ~29 fold higher than that in either the stn1Δ or ten1Δ mutant, demonstrating a predominant role of Cdc13 in inhibiting telomere fusion. Chromosomal fusion readily occurred in the telomerase-null SY14 strain, further verifying the default role of intact telomeres in inhibiting chromosome fusion.

Creating functional chromosome fusions in yeast with CRISPR-Cas9.

CRISPR-Cas9-facilitated functional chromosome fusion allows the generation of a series of yeast strains with progressively reduced chromosome numbers that are valuable resources for the study of fundamental concepts in chromosome biology, including replication, recombination and segregation. We created a new yeast strain with a single chromosome by using the protocol for chromosome fusion described herein. To ensure the accuracy of chromosome fusions in yeast, the long redundant repetitive sequences near linear chromosomal ends are deleted, and the fusion orders are correspondingly determined. Possible influence on gene expression is minimized to retain gene functionality. This protocol provides experimentally derived guidelines for the generation of functional chromosome fusions in yeast, especially for the deletion of repetitive sequences, the determination of the fusion order and cleavage sites, and primary evaluation of the functionality of chromosome fusions. Beginning with design, one round of typical chromosome fusion and functional verifications can be accomplished within 18 d.

CRISPR-Cas9 Facilitated Multiple-Chromosome Fusion in Saccharomyces cerevisiae.

Eukaryotic cells usually contain multiple linear chromosomes. Recently, we artificially created a functional single-chromosome yeast via sequential two-chromosome fusion utilizing the high performance of the CRISPR-Cas9 system and homologous recombination in Saccharomyces cerevisiae. In this paper, we adapted this method for the simultaneous fusion of multiple chromosomes. We demonstrated the fusion of two, two-chromosome sets with a 75% positive rate and three-chromosome fusions with a 50% positive rate. We also found that by using an additional selection marker, the positive rate of two-chromosome fusions reached 100%. Due to the simplicity, efficiency, and portability of this method, we expect that it can be easily adapted for multiple-chromosome fusions in other organisms.

Purification and characterization of alginate lyase from streptomyces species strain A5 isolated from banana rhizosphere.

To characterize the alginate lyase produced by rhizosphere Streptomyces, Streptomyces sp. A5 was isolated from banana rhizosphere, and its extracellular lyase was purified to an electrophoretically homogeneous state. The lyase has a molecular mass of 32 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum temperature and pH were 37 degrees C and pH 7.5, respectively. Ninety-two percent of the activity was lost after incubation at 70 degrees C and pH 7.5 for 20 min. The enzyme was inhibited by 0.05 M SDS and 2 mM Hg2+, Cu2+, and Fe3+, but EDTA enhanced the enzyme activity. The Km value of the lyase was 0.13 mg mL-1 with the substrate sodium alginate. The lyase had substrate specificity for polyguluronate units in the alginate molecules. The alginate oligomers prepared by the lyase show growth-promoting activity on the roots of banana plantlets. These results indicated that the encapsulation method using alginate microbeads to inoculate beneficial streptomycete strains might be beneficial to the root growth of banana plantlets.