Enzyme Research Articles

Mechanism of transglutaminase on film-forming and structural properties of soybean protein and its fractions: A study in different pH environments

In this study, transglutaminase (TGase) was introduced into soybean protein isolate (SPI) and its major fractions, 7S and 11S globulins combined proteins (CP), and the effects of TGase on the physicochemical properties of SPI and CP films were explored in pH values of 5.0, 6.0, 7.0, and 8.0. The results suggested that TGase facilitated the conversion of β-turn and random coil to β-sheet structure in protein films, resulting in a more ordered and table protein network. Homogeneous and dense microscopic films were observed and resulted in a reduction of over 20% in the water vapor permeability (WVP) for both TGase-modified SPI and CP films. However, the effect of enzymatic action also greatly depends on the regulation of protein conformation by pH environment. The tensile strength of CP films prepared at pH 6.0 modified by TGase increased by more than 26% (from 6.21 MPa to 7.87 MPa), and the elongation of all film samples prepared at pH 7.0 and 8.0 modified by TGase increased by more than 76% (from 16.25%–19.24% to 33.92%–36.35%). Consequently, it is proposed that the mechanism of TGase-catalyzed film formation of soybean protein is related to the catalytic affinity of TGase for different subunits and the type of crosslinks formed. This aims to provide a valuable theoretical reference for the rational application of crosslinkers in protein-based products.

Innovative Approach to Accelerate Wound Healing: Synthesis and Validation of Enzymatically Cross-Linked COL-rGO Biocomposite Hydrogels.

In this study, an innovative conductive hybrid biomaterial was synthetized using collagen (COL) and reduced graphene oxide (rGO) in order for it to be used as a wound dressing. The hydrogels were plasticized with glycerol and enzymatically cross-linked with horseradish peroxidase (HRP). A successful interaction among the components was demonstrated by FTIR, XRD, and XPS. It was demonstrated that increasing the rGO concentration led to higher conductivity and negative charge density values. Moreover, rGO also improved the stability of hydrogels, which was expressed by a reduction in the biodegradation rate. Furthermore, the hydrogel's stability against the enzymatic action of collagenase type I was also strengthened by both the enzymatic cross-linking and the polymerization of dopamine. However, their absorption capacity, reaching values of 215 g/g, indicates the high potential of the hydrogels to absorb fluids. The rise of these properties positively influenced the wound closure process, achieving an 84.5% in vitro closure rate after 48 h. These findings clearly demonstrate that these original composite biomaterials can be a viable choice for wound healing purposes.

Nutritional and sensory parameters of amazake from the recycling of stale bread

Stale bread is a waste product with a potential to be recycled. One way to manage this waste material is to process it by fermentation for the purpose of food production. This paper proposes the use of stale wheat and rye bread as ingredients in amazake, a liquid dessert traditionally obtained from rice by fermentation with the koji mould Aspergillus oryzae, followed by liquefaction by the action of fungal enzymes. The stale bread was introduced instead of rice at both the koji stage (wheat bread) and the liquefaction stage (wheat and rye bread). The resulting products had an extended volatile compound profile, from 5 to 15 compounds identified, and modified sensory parameters, compared to the traditional version. Amazake containing bread had an increased protein content, from 1.10 to 6.4 g/100 g, and were more abundant in dietary fibre (up to a maximum of 1.8 g/100 g), additionally enriched with a soluble fraction. The proposed procedure of obtaining of new formula amazake can be directly applied in households to reduce the amount of discarded bread. Due to its simplicity, it also has the potential for further modification in terms of production scale and product parameters.

Systematic Review on Pathology and Drug Efficacy Clinical Trials (1973-2023) for Cognitive Impairment and Alzheimer’s Dementia

Rationale: The systematic review evaluates the results of last fifty years (1973-2023) of clinical trials on pathology and treatment for cognitive impairment including Alzheimer’s dementia (AD dementia). Objectives: Alzheimer’s dementia is a growing public health concern worldwide. The systematic review analyzes the disease confirming pathological findings presented by modern imaging techniques MRI/ PET. In addition, we analyze the success of fifty years of therapeutic advancements of the neurological disabilities and count on the safe drugs to treat clinical conditions of AD dementia. Findings: We followed the PRISMA guidelines to determine the inclusion and exclusion criteria for the selection of clinical records collected from the NCBI databases. We analyzed the drug efficacy results on the three aspects of the AD brain: (a) morphological deformation of the choroid plexus and hippocampus; (b) senile plaques with amyloid beta42 (Abeta42) including hyperintensities of neurons; and (c) inhibitory action of acetylcholinesterase enzyme. The pathological findings include detection of Abeta42 plaques in cerebral cortex and retention ability of trial drugs in cerebrospinal fluid versus blood plasma of AD patients in the context of disease progression and treatment efficacy. The clinical trial records demonstrated evidence of genetic susceptibility factor(s) clustered in European populations. The susceptibility is also found due to mutations in the presenilin-1 gene and expression of the ApoEε-allele among the population. The clinical records demonstrate moderate efficacy of cholinesterase inhibitors Donepezil and Rivastigmine in improving cognition. The antibodies aducanumab, donanemab, and lecanemab show low to moderate success in removing plaques and reducing plasma Abeta burden. Conclusion: The cholinesterase inhibitors demonstrate moderate success in improving cognition. However, the overall efficacy of antibody treatment was poor. The findings suggest a need for new generation drugs which can clear plaques and improve cognition for AD.

Integrating molecular docking and molecular dynamics simulation approaches for investigation of the affinity and interactions of quercetin with Class D beta-lactamase, OXA-10

Introduction: The misuse of β-lactam antibiotics has led to the development of β-lactamase-producing organisms, which inhibit β-lactam activity by hydrolyzing the peptide bond. This study aims to investigate the inhibitory effect of quercetin, a natural composite and isoquinoline alkaloid, on β-lactamase enzyme action, potentially increasing antibiotic effectiveness. Materials and Methods: This study utilized computational techniques like molecular docking and MD simulation to predict the binding mode and possible conformation poses of quercetin with the OXA-10 β-lactamase enzyme. Autodock software was used for docking, while Gromacs 2019.6 package was used for MD simulations to study molecular complex behavior over time. Results: The outcomes of the molecular docking analysis revealed a favorable interaction between quercetin and the OXA-10 β-lactamase enzyme, as evidenced by a binding energy of -5.95 kcal/mol and a suitable binding mode. MD simulations confirmed the docking results, showing stable hydrogen bonds between Quercetin and OXA-10, as well as comparable RMSD, RMSF, SASA values, and other parameters. Discussion: This research shows the potential of quercetin, a natural compound with multiple medicinal effects, as a possible inhibitor of the class D type β-lactamase OXA-10. Therefore, this study maintains valuable intuition for designing new inhibitors of antimicrobial resistance to combat β-lactamase activity.

Multifunctional cerium oxide nanozymes with high ocular surface retention for dry eye disease treatment achieved by restoring redox balance

Dry eye disease (DED) is a kind of multifactorial ocular surface disease that displays ocular discomfort, visual disturbance, and tear film instability. Oxidative stress is a fundamental pathogenesis in DED. An imbalance between the reactive oxygen species (ROS) level and protective enzyme action will lead to oxidative stress, cell dysfunction, tear hyperosmolarity, and inflammation. Herein, a multifunctional cerium oxide nanozyme with high ocular surface retention property was designed to neutralize over-accumulated ROS and restore redox balance. Cerium oxide nanozymes were fabricated via branched polyethylenimine-graft-poly (ethylene glycol) nucleation and dispersion, followed by phenylboronic acid (PBA) functionalization (defined as Ce@PB). Due to the dynamic chemical bonding formation between the PBA segment and the cis-diol groups in the mucin layer of the tear film, Ce@PB nanozymes possess good adhesive capability to the ocular surface, thus extending the drug's retention time. On the other hand, Ce@PB nanozymes could mimic the cascade processes of superoxide dismutase and catalase to maintain intracellular redox balance. In vitro and in vivo studies suggest that such multifunctional nanozymes possess good biocompatibility and hemocompatibility. More importantly, Ce@PB nanozymes treatment in the animal model could repair corneal epithelial defect, increase the number of goblet cells and promote tear secretion, thus achieving an effective treatment for DED. Statement of significance•PBA-functionalized bPEI-g-PEG-based cerium oxide (Ce@PB) nanozymes were designed and fabricated.•The Ce@PB nanozymes have superoxide dismutase (SOD) and catalase (CAT) enzyme-like activity scavenging excessive intracellular reactive oxygen species (ROS).•The Ce@PB nanozymes demonstrate extended retention on the ocular surface and can effectively treat dry eye disease.

Cytoarchitectural differences in reproductive organs of some polycystic ovary-like induced animal models

Polycystic ovary syndrome (PCOS) is the most common gynaecological, endocrine disorder that occurs during reproductive age and is a significant cause of anovulatory infertility. Letrozole is an aromatase inhibitor which negates the action of the aromatase enzyme, which results in the buildup of male hormones (testosterone) in the females, causing hyperandrogenism, which is a hallmark of Polycystic Ovarian Syndrome. Mifepristone (RU486) is a progestin antagonist that acts to arrest the actions of the progesterone hormone, resulting in follicular atresia and anovulation. DHEA is an androgen which was also administered in a bid to cause hyperandrogenism in the rats.This study aimed to evaluate the effects of these hormones on the cytoarchitecture of the ovaries and uterus to assess their various PCOS-like histological features.Animals were grouped mainly into three: Letrozole, Mifepristone and DHEA groups, which were further divided into two subgroups each, administered low and high doses of letrozole orally, Mifepristone and Dehydroepiandosterone (DHEA) subcutaneously. Each of the subgroups also had a comparison control group. Following the completion of administration, the Wistar rats were euthanized, and their ovaries and uterus were collected for histological analysis.Increased proliferation of ovarian follicles was noted in the treated groups compared to control, as well as thickening of the endometrial layer.

Action of AA9 lytic polysaccharide monooxygenase enzymes on different cellulose allomorphs

Lytic polysaccharide monooxygenase (LPMO)-catalyzed oxidative processes play a major role in natural biomass conversion. Despite their oxidative cleavage at the surface of polysaccharides, understanding of their mode of action, and the impact of structural patterns of the cellulose fiber on LPMO activity is still not fully understood. In this work, we investigated the action of two different LPMOs from Podospora anserina on celluloses showing different structural patterns. For this purpose, we prepared cellulose II and cellulose III allomorphs from cellulose I cotton linters, as well as amorphous cellulose. LPMO action was monitored in terms of surface morphology, molar mass changes and monosaccharide profile. Both PaLPMO9E and PaLPMO9H were active on the different cellulose allomorphs (I, II and III), and on amorphous cellulose (PASC) whereas they displayed a different behavior, with a higher molar mass decrease observed for cellulose I. Overall, the pretreatment with LPMO enzymes clearly increased the accessibility of all types of cellulose, which was quantified by the higher carboxylate content after carboxymethylation reaction on LPMO-pretreated celluloses. This work gives more insight into the action of LPMOs as a tool for deconstructing lignocellulosic biomass to obtain new bio-based building blocks.

Sequential effects of autoclaved heat treatment and electron beam irradiation on acorn starch: Multiscale structural differences and related mechanisms

In this study, the differences in the modification effects and related mechanisms of different times (20 and 40 min) of autoclaved heat (AH) treatment and different doses (2 and 4 kGy) of electron beam irradiation (EBI) in different sequences of effects on acorn starch were investigated. The results showed that both AH and EBI reduced the amylose content (22.70 to 19.59%) and enthalpy (10.28 to 1.84%) of starch but increased the resistant starch content (53.69 to 64.11%). AH treatment made the crystalline regions of the residual starch granules denser, which was resistant to the action of amylase enzymes. EBI degraded the long chain of starch, which increased the solubility. Notably, EBI pretreatment improves the reactive sites by inducing depolymerization and disorder in starch internal structure, thus increasing the modification extent of AH-modified starch, forming starch with lower viscosity, better hydration, and digestibility resistance, therefore being used as an ingredient for functional foods.

Nanozybiotics: Advancing Antimicrobial Strategies Through Biomimetic Mechanisms.

Infectious diseases caused by bacterial, viral, and fungal pathogens present significant global health challenges. The rapid emergence of antimicrobial resistance exacerbates this issue, leading to a scenario where effective antibiotics are increasingly scarce. Traditional antibiotic development strategies are proving inadequate against the swift evolution of microbial resistance. Therefore, there is an urgent need to develop novel antimicrobial strategies with mechanisms distinct from those of existing antibiotics. Nanozybiotics, which are nanozyme-based antimicrobials, mimic the catalytic action of lysosomal enzymes in innate immune cells to kill infectious pathogens. This review reinforces the concept of nanozymes and provides a comprehensive summary of recent research advancements on potential antimicrobial candidates. Initially, nanozybiotics are categorized based on their activities, mimicking either oxidoreductase-like or hydrolase-like functions, thereby highlighting their superior mechanisms in combating antimicrobial resistance. The review then discusses the progress of nanozybiotics in treating bacterial, viral, and fungal infections, confirming their potential as novel antimicrobial candidates. The translational potential of nanozybiotic-based products, including hydrogels, nanorobots, sprays, bandages, masks, and protective clothing, is also considered. Finally, the current challenges and future prospects of nanozybiotic-related products are explored, emphasizing the design and antimicrobial capabilities of nanozybiotics for future applications.

A Novel Bio-Adhesive Based on Chitosan-Polydopamine-Xanthan Gum for Glass, Cardboard and Textile Commodities.

The escalating environmental concerns associated with petroleum-based adhesives have spurred an urgent need for sustainable alternatives. Chitosan, a natural polysaccharide, is a promising candidate; however, its limited water resistance hinders broader application. The aim of this study is to develop a new chitosan-based adhesive with improved properties. The polydopamine association with chitosan presents a significant increase in adhesiveness compared to pure chitosan. Polydopamine is synthesized by the enzymatic action of laccase from Trametes versicolor at pH = 4.5, in the absence or presence of chitosan. This pH facilitates chitosan's solubility and the occurrence of catechol in its reduced form (pH < 5.5), thereby increasing the final adhesive properties. To further enhance the adhesive properties, various crosslinking agents were tested. A multi-technique approach was used for the characterization of formulations. The formulation based on 3% chitosan, 50% polydopamine, and 3% xanthan gum showed a spectacular increase in adhesive properties when tested on glass, cardboard and textile. This formulation increased water resistance, maintaining the adhesion of a sample soaked in water for up to 10 h. For cardboard and textile, material rapture occurred, in mechanical tests, prior to adhesive bond failure. Furthermore, all the samples showed antiflame properties, expanding the benefits of their use. Comparison with commercial glues confirms the remarkable adhesive properties of the new formulation.

How D-amino acids embedded in the protein sequence modify its digestibility: Behaviour of digestive enzymes tested on a model peptide used as target

D-amino acids can affect the action of digestive enzymes, hence the protein digestion. In this work the behaviour of the main stomach and gut digestive enzymes (pepsin, trypsin, and chymotrypsin) in the presence of D-amino acids in the protein chain was monitored over time using a model peptide, Ac-LDAQSAPLRVYVE-NH2 (belonging to β-lactoglobulin, position 48–60), where L-amino acids were systematically substituted by D-amino acids. The results showed several changes in the behaviour of digestive enzymes, not only when the D-amino acids are inserted at the specific cleavage sites (after Val-57), but in some cases also when in distant positions. The effect seemed more pronounced in the case of pepsin rather than the gut enzymes, possibly indicating a better resilience of the upper gut phase of digestion to racemization. These results demonstrated that racemization could impair nutritional value by slowing down digestibility and has different effects according to the enzyme/amino acids involved.

Nicotinamide N-Methyltransferase (NNMT): A New Hope for Treating Aging and Age-Related Conditions.

The complex process of aging leads to a gradual deterioration in the function of cells, tissues, and the entire organism, thereby increasing the risk of disease and death. Nicotinamide N-methyltransferase (NNMT) has attracted attention as a potential target for combating aging and its related pathologies. Studies have shown that NNMT activity increases over time, which is closely associated with the onset and progression of age-related diseases. NNMT uses S-adenosylmethionine (SAM) as a methyl donor to facilitate the methylation of nicotinamide (NAM), converting NAM into S-adenosyl-L-homocysteine (SAH) and methylnicotinamide (MNA). This enzymatic action depletes NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and generates SAH, a precursor of homocysteine (Hcy). The reduction in the NAD+ levels and the increase in the Hcy levels are considered important factors in the aging process and age-related diseases. The efficacy of RNA interference (RNAi) therapies and small-molecule inhibitors targeting NNMT demonstrates the potential of NNMT as a therapeutic target. Despite these advances, the exact mechanisms by which NNMT influences aging and age-related diseases remain unclear, and there is a lack of clinical trials involving NNMT inhibitors and RNAi drugs. Therefore, more in-depth research is needed to elucidate the precise functions of NNMT in aging and promote the development of targeted pharmaceutical interventions. This paper aims to explore the specific role of NNMT in aging, and to evaluate its potential as a therapeutic target.

The Efficiency of Calcium Oxide on Microbial Self-Healing Activity in Alkali-Activated Slag (AAS)

Alkali-activated slag (AAS) materials are one of the most promising sustainable construction composites. These novel materials are highly characterized by their improved mechanical and durability properties. Nevertheless, the high shrinkage rate hinders their full-scale applications. The low Ca/Si ratio, complex hydration process, and fine pore microstructure are the main causes of the reported shrinkage behavior. This study introduces Bacillus subtilis culture for healing the cracking behavior. The enzymatic action leads to precipitating calcium carbonate crystals that fill AAS cracks and pores. Incorporating calcium oxide has been recommended in multiple studies. The main purpose of adding calcium oxide is to enhance the engineering properties of AAS and provide more calcium ions for the biochemical reactions induced by the added bacteria. However, inconsistent findings about the influence of calcium oxide have been reported. This research provides further insights into the effect of calcium oxide (CaO) on the performance of microbial self-healing efficiency in AAS composite. The results highlight that incorporating calcium oxide as 7% of the binder partial replacement has an impact on the engineering properties of bio-AAS materials. The study recommends correlating the percentage of free calcium ions within the AAS mixture with the microbial activity.

Experimental investigation and molecular simulations of quinone related compounds as COX/LOX inhibitors.

Quinone-containing compounds have risen as promising anti-inflammatory targets; however, very little research has been directed to investigate their potentials. Accordingly, the current study aimed to design and synthesize group of quinones bearing different substituents to investigate the effect of these functionalities on the anti-inflammatory activities of this important scaffold. The choice of these substituents was carefully done, varying from a directly attached heterocyclic ring to different aromatic moieties linked through a nitrogen spacer. Both in vitro and in vivo anti-inflammatory activities of the synthesized compounds were assessed relative to the positive standards: celecoxib and indomethacin. The in vitro enzymatic and transcription inhibitory actions of all the synthesized compounds were tested against cyclooxygenase-2 (COX-2), cyclooxygenase-1 (COX-1), and 5-lipoxygenase (LOX) and the in vivo gene expression of Interleukin-1, interleukin 10, and Tumor Necrosis Factor-α (TNF-α) were determined. The IC50 against COX-1 and COX-2 enzymes obtained by the immunoassay test revealed promising activities of sixteen compounds with selectivity indices higher than 100-fold COX-2 selectivity. Out of those, four compounds revealed selectivity indices comparable to celecoxib as a reference drug. Furthermore, all the tested compounds inhibited LOX with an IC50 in the range of 1.59-3.11µM superior to that of the reference drug used; zileuton (IC50 = 3.50µM). Consequently, these results highlight the promising LOX inhibitory activity of the tested compounds. The obtained in vivo paw edema results showed high inhibitory percentage for the compounds 9a, 9b, and 11a with the significant lower TNF-α relative mRNA expression for compounds 5a, 5d, 9a, 9b, 12d, and 12e. Finally, in silico docking of the most active compounds (5b, 5d, 9a, 9b) against COX2 enzymes presented an acceptable justification of the obtained in vitro inhibitory activities. As a conclusion, Compounds 5b, 5d, 9a, 9b, and 11b showed promising results and thus deserves further investigation.

Vanadium toxicity was alleviated by supplementation of silicon in tomato seedlings: Upregulating antioxidative enzymes and glyoxalase system

The primary goal of this research is to investigate the mitigating effect of silicon (Si; 2 mM) on the growth of tomato seedlings under vanadium (V; 40 mg) stress. V stress caused higher V uptake in leaf, and enhanced concentration of leaf anthocyanin, H2O2, O2•−, and MDA, but a decreased in plant biomass, root architecture system, leaf pigments content, mineral elements, and Fv/Fm (PSII maximum efficiency). Si application increased the concentrations of crucial antioxidant molecules such as AsA and GSH, as well as the action of key antioxidant enzymes comprising APX, GR, DHAR, and MDHAR. Importantly, oxidative damage was remarkably alleviated by upregulation of these antioxidant enzymes genes. Moreover, Si application enhanced the accumulation of secondary metabolites as well as the expression their related-genes, and these secondary metabolites may restricted the excessive accumulation of H2O2. In addition, Si rescued tomato plants against the damaging effects of MG by boosting the Gly enzymes activity. The results confirmed that spraying Si to plants might diminish the V accessibility to plants, along with promotion of V stress resistance.

REGULATION OF ENZYME-DEPENDENT LYSIS OF MICROBIAL CELLS: IS THE EFFECTOR TARGET ENZYME OR SUBSTRATE?

In this work, an attempt was made to analyze the literature data regarding the effectors of bacterial lysis in the presence of various bacteriolytic enzymes. Despite the differences between such enzymes, it is possible to identify certain general patterns of their action on a highly complex substrate - a living bacterial cell protected by a cell wall and additional complexes of biopolymers associated with it. Chicken and human lysozymes are the best known of these enzymes. They have some structural differences, but are generally very similar in properties. Understanding the characteristics of the antibacterial action of bacteriolytic enzymes present both in medications and in the human immune system is extremely important for the development of new approaches to combating bacterial infections, including antibiotic-resistant ones. Moreover, certain logical and methodological approaches used to study bacteriolytic enzymes can be extremely useful for studying and describing other enzymes that affect complex polymer substrates in real biological situations.

Role of FGF23 and alkaline phosphatase in bone health: Case-based clinico-physiologic discussion

Proper bone development requires the coordinated and calibrated action of various cells, hormones, enzymes and nutrients. In this paper, we present two clinical cases of metabolic bone disorders – one with excessive fibroblast growth factor-23 (FGF23) and the other, with low alkaline phosphatase. FGF23 and alkaline phosphatase are not-so-well-known players in bone health. This paper puts the spotlight on these two, and discusses their role in bone development, and how abnormal levels lead to disease.

Morphological, Physiological, Biochemical and Metabolite Analyses of Parenchyma Cells Reveal Heartwood Formation Mechanism of Schima superba

A sapwood tree is a species in which the sapwood does not differ significantly from the heartwood and cannot be classified by shades of color. It is generally accepted that heartwood has a higher economic value than sapwood, but most of the studies related to heartwood formation have focused on heartwood trees, with less research on sapwood trees. In this paper, we take the sapwood tree Schima superba as the research object and analyze the physiological and biochemical changes in the process of heartwood formation by studying the anatomical structure of parenchyma cells, and then further explore the main categories of metabolites and compositional changes. The results showed that during heartwood formation, the parenchyma cells become inactive and the nucleus disappears, while at the same time, the storage substance starch is gradually degraded under the action of enzymes and transformed into secondary metabolites, which include terpenoids, phenols and alkaloids. The accumulation of white and colorless compounds in large quantities in the heartwood, which has some effect on the heartwood color, is an important reason why the heartwood in Schima superba shows normal formation but no difference in color from the sapwood. This study fills a gap in the mechanism of heartwood formation in sapwood trees.

Replacing traditional nursery soil with spent mushroom substrate improves rice seedling quality and soil substrate properties.

Currently, large quantities of spent mushroom substrate (SMS) are produced annually. Because SMS has high water retention and nutrients, it has great potential to replace traditional topsoil for raising seedlings in agricultural production. However, few studies have examined the effects of substituting SMS for paddy soil on rice seedling growth and soil nutrients. SMS was mixed with rice soil in different proportions (20%, 50%, and 80%), and chemical fertilizer, organic fertilizer, and peat substrate were added in addition to equivalent nitrogen as a traditional seedling nursery method for comparison. Compared to traditional paddy soil (CK), the seedling qualities of the three SMS ratio treatments were all higher. Adding SMS at different ratios promoted rice seedling root growth, elevated the soluble protein concentration, and amplified the superoxide dismutase (SOD) enzymatic action in rice seedlings. Total porosity and aeration porosity of the soil increased by 17.40% and 32.90%, respectively. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) increased by 21.26-118.48%, 50.44-71.68%, and 23.08-80.17%, respectively. Besides, the relative abundance of Bacillus, Bacteroidetes, and other bacteria as well as the abundance of Ascomycota were all significantly increased. Adding 50% SMS increased the abundance of Pseudomonas by 8.42 times. The seedling quality of the 50% SMS treatment was even higher than chemical fertilizer and organic fertilizer treatments, only second to the peat substrate treatment. In summary, partial substitution of paddy soil with SMS can ameliorate substrate properties, improve seedling quality, and increase microbial diversity, indicating the suitability of SMS as a replacement for rice soil in seedling substrates. The 50% SMS ratio is the best. This study provides a basis for SMS to replace traditional rice soil in seedling cultivation.