Mushroom Surface Research Articles

Trichoderma thailandense sp. nov. (Hypocreales, Hypocreaceae), a new species from Thailand

A new species of microfungus, described herein as Trichoderma thailandense was isolated from the pileus surface of oyster mushroom and upland black rice samples in Thailand. This species is described using morphological characteristics and molecular multi-gene analyses. Based on multi-gene phylogenetic analyses of the internal transcribed spacer (ITS) region of the rDNA, RNA polymerase subunit II gene sequences (rpb2), and translation elongation factor 1-α (tef1-α) gene revealed that the position of T. thailandense is well-supported within Harzianum clade of the genus Trichoderma, but distinct from other all other known species. A full description, illustrations and a phylogenetic tree showing the position of T. thailandense are provided.

Bio-inspired powder bed fusion 3D printed surfaces for enhanced critical heat flux and boiling heat transfer

The thermal performance and sizing of two-phase heat exchangers employed in various industries can be significantly improved by modifying the surface topology of tubes. The advancement in metal 3D printing technology enables the modification of surfaces to generate distinct patterns that enhance the heat transfer coefficient. This study aligns with these advances by investigating the boiling heat transfer performance of 3D printed surfaces using methanol as the working fluid. The enhanced surfaces studied include four bio-inspired 3D printed surfaces (Mushroom, Cactus, Petal, and Torus), each strategically designed to improve the heat transfer coefficient (HTC) and delay the onset of critical heat flux (CHF). The primary objective of this research is to discuss and analyze the heat transfer mechanism in terms of bubble dynamics, particularly focusing on the interaction between surface morphology and bubble behavior. Experimental results reveal significant enhancements in CHF and HTC for 3D printed surfaces compared to plain surfaces. Among the 3D printed surfaces, the Mushroom surface exhibits the highest enhancement in CHF of 88 % compared to the plain surface. Similarly, the maximum HTC enhancements are 138 %, 86 %, 65 %, and 46 % for the Mushroom, Cactus, Petal, and Torus surfaces, respectively, compared to the plain surface. The methodologies and findings of this study are poised to have a lasting impact on the field, potentially opening new avenues for improving the efficiency and effectiveness of various two-phase heat exchangers.

Optimization of active pectin coating formulation and its effect on surface morphology and shelf-life of white button mushroom (Agaricus bisporus)

The present work aimed to optimize an active pectin-based coating to preserve microbial and enzymatic stability and maintain the quality parameters of white button mushrooms (WBM), thus increasing their shelf stability. d-optimal mixture design was implemented to study the effect of pectin (X1), ascorbic acid (X2), and ethylene-diamine-tetra acetic acid (EDTA) (X3) on polyphenol oxidase (PPO) inhibition, browning index, and total phenolic content. The optimal coating was a mixture of 2.55% w/v pectin, 0.67% w/v ascorbic acid, and 0.78% w/v EDTA. Further, the optimally coated WBM was stored for 6 days at 20 ± 1 °C. The coating on WBM significantly prevented the growth of natural microflora in the sample. Similarly, a maximum of 84% PPO inhibition was achieved at the end of the storage period. A minimum browning index (BI) of 66 was observed after six days of storage, significantly lower than that of the uncoated sample with a BI of 72.72 ± 0.90. Maximum phenolic content of 10.23 mgGAE/g WBM (dry basis) was preserved till day 6, while the antioxidant capacity was 7.16 ± 0.20 mg GAEAOC/g WBM (dry basis). Based on microbial safety and overall quality parameters, the optimal pectin-based ascorbic acid and EDTA-enriched coating led to a shelf-life of 4 days against 2 days for uncoated mushrooms at 20 °C. The optimized coating of mushrooms resulted in competitive inhibition of PPO. Fourier transform infrared (FTIR) spectroscopy revealed that EDTA and optimized coating modulated the secondary structure conformation in the amide I region. Microstructural analysis of the mushroom cap surface through scanning electron microscopy (SEM) showed that the optimized coating formed a homogeneous protective barrier on the mushroom surface, leading to the closure of intercellular spaces on the surface. The optimized coating can help mitigate postharvest losses due to the high perishability of white button mushrooms and provides a valuable solution for the industry to enhance product quality and safety.

Iron diselenide/carbon black loaded mushroom-shaped evaporator for efficiently continuous solar-driven desalination

Solar-driven desalination is an environmentally sustainable method to alleviate the problems of freshwater scarcity and the energy crisis. However, how to improve the synergy between the photothermal material and the evaporator to achieve high photothermal conversion efficiency simultaneously, excellent thermal management system and good salt resistance remains a challenge. Here, a mushroom-shaped solar evaporation device is designed and fabricated with iron diselenide/carbon black (FeSe2/CB) coated cellulose acetate (CA) film as mushroom surface and cotton swab as mushroom handle, which presented high solar-driven evaporation and excellent salt resistance. Thanks to the unique photothermal effect and the synergistic effect, the FeSe2/CB composites enabled a promising photothermal conversion efficiency of up to 65.8 °C after 180 s. The mushroom-shaped evaporation device effectively overcomes water transport and steam spillage channel blockage caused by salt crystallization through its unique vertical transport water channels and conical air–water interface. When exposed to real sunlight, the solar evaporation rate of the steam generation structure reached as high as 2.03 kg m−2 h−1, which is more than 13 times higher than natural evaporation. This study offered new insights into the higher solar-driven evaporation rate and salt-blocking resistance of the FeSe2/CB mushroom-shaped solar evaporation device for solar-powered water production.

Scanning Electron Microscopy and Triple TOF-LC-MS-MS Analysis of Polyphenols from PEF-Treated Edible Mushrooms (L. edodes, A. brunnescens, and P. ostreatus).

Pulsed electric fields (PEF) technology has been used as a sustainable method for extracting antioxidant bioactive compounds from different food matrices. In the present study, the optimal conditions of PEF extraction for mushrooms (2.5 kV/cm, 50 kJ/kg, 6 h) were applied to Lentinula edodes, Agaricus brunnescens, and Pleurotus ostreatus to evaluate the total antioxidant capacity of the extracts, followed by the Triple TOF-LC-MS-MS analysis of the phenolic profile compared to A. bisporus by high-performance liquid chromatography coupled to mass spectrophotometry. In addition, the microporation effect of the technology on the mushroom surface was evaluated using scanning electron microscopy. A comparison was made with a maceration extraction (aqueous stirring for 6 h). The results showed that PEF-assisted extraction enhanced the recovery of antioxidant compounds such as 3,5-dicaffeoylquinic and cinnamic acid with contents up to 236.85 µg/100 g dry weight and 2043.26 µg/100 g dry weight from A. bisporus, respectively. However, mixed results were obtained for certain phenolic compounds, including vanillic acid from L. edodes, ellagic acid from P. ostreatus, and thymol from all mushrooms. These results indicate that the application of PEF technology is effective for the extraction of antioxidant compounds in fungal matrices by creating micropores in cell membranes that allow great recovery in matrices with high content of bioactive compounds.

In situ screening of sodium sulfite residue on edible mushroom using SERS active paper swab

In the present study, a printing paper functionalized with Ag nanoparticles (AgNPs) was used as a flexible surface-enhanced Raman spectroscopy (SERS) swab (AgNP@FP) to evaluate its ability to detect sodium sulfite residues on the surface of edible mushrooms. The results showed that the prepared AgNP@FP swab had fingerprint-like signals (at 620 and 927 cm–1), which could serve as a clear confirmation of the analyte. In addition, the swab not only exhibited good repeatability, with spot-to-spot variation of < 2.6% at 620 cm–1 signal intensity, but it also met the requirement of commercial transportation as the peak intensity at 620 cm–1 remained at 57.84% of its initial value after 5 days of storage. The sensitivity of the substrate to sodium sulfite on the surface of oyster mushroom and enoki mushroom was as low as 0.2 mg/mL. The limit of detection (LOD) values of the sulfite residue on the surface of oyster and enoki mushrooms were 1.2 and 1.6 mg/kg, respectively. This study demonstrated that the AgNP@FP swab provided a simple tool for obscure and in situ screening of residues on the surface of agricultural products.

Straw-based compost cultivation disproportionally contributes to the environmental persistence of antibiotic resistance from raw cattle manure to organic vegetables

Cattle manure, is a reservoir of antimicrobial resistance genes, but the mechanisms by which they migrate from farm to table remain obscure. Here, we chose Agaricus bisporus as a model vegetable to examine such migration and characterized the resistome in 112 metagenomes covering samples from raw manure, composting substrates, rhizosphere, and surfaces of mushrooms. A total of 1864 resistance genes, representing 113 unique mechanisms of resistance, were identified. Monensin treatment on beef specifically enriched fecal resistance genes within Moraxellaceae, but this effect did not persist in downstream mushrooms. Interestingly, we found that resistance genes were significantly more enriched on mushroom surfaces when cultivated with corn-based compost compared to rice and wheat, likely a result of the disproportional propagation of Pseudomonadaceae and varied ability of lateral gene transfer. Importantly, our sequence alignment together with genome-centric analysis observed that 89 resistance genes, mainly conferring resistance to drug and biocide (20.22%) and mercury (19.10%), were shared across all types of samples, indicating an efficient transmission of resistance in food production. Moreover, co-occurrence of genes conferring resistance to different compounds frequently occurred in parallel with microbial migration. Together, we present the influences of antibiotic treatment and straw-based composting on resistome along the mushroom production chain (from manure to straw-based compost, rhizosphere of compost cultivated mushroom and surface of mushroom) and highlighted the risks of resistance genes migration.

Effects of ultrasonic treatment on the surface bacteria of Lyophyllum decastes during storage

This study explores the relationship between the storage quality and bacterial microflora in the mushroom Lyophyllum decastes. The surface bacteria of L. decastes were separated by combining the traditional culture plate separation and 16S rRNA sequencing method, to study the effects of ultrasonic (US) treatment on the surface bacteria of L. decastes during storage. The results demonstrated that Pantoea agglomerans and Pseudomonas fluorescens were among the 15 culturable bacteria isolated with traditional plate method during storage, belonging to 2 phyla and 7 genera. US treatment could inhibit the growth and significantly increase cell membrane permeability, and contents extravasation in P. agglomerans, though its inhibitory effect on P. fluorescens was less. The 16S rRNA sequencing revealed, bacteria from 9 phyla and 35 genera were isolated, and P. fluorescens was the dominant species throughout the storage time. These results indicated that the composition of mushroom surface microflora of Control (CK) and US groups are similar, and the bacterial microflora networks analysis also showed a positive correlation. The KEGG annotation for the functional classification of the bacteria showed that a total of 328 pathways were acquired at the KEGG l3 level, and the relative abundance of membrane transport, amino acid metabolism, carbohydrate metabolism, and energy metabolism pathway was high. Moreover, the relative abundance of the surface bacteria of L. decastes also decreased. Hence, the US treatment had a better bacteriostatic effect, maintained the whiteness index and firmness, and improved the sensory quality of L. decastes during storage.

Effects of gas type and cold plasma treatment time on Lecanicillium fungicola spores reduction and changes in qualitative, chemical, and physiological characteristics of button mushroom during postharvest storage

This study aimed to inhibit the growth of Lacanicillium fungicola and improve the quality of button mushroom during a 21-day storage time at 4°C using the treatment of surface dielectric barrier discharge plasma. Three gases of argon (Ar), surface evaporation of hydrogen peroxide (H2O2vapor) by argon and H2O2vapor by air were used as the injecting gas within processing times of 30, 60, 120, and 180 s. The results showed that 180 s treatment with H2O2vapor+Air plasma decreased L. fungicola spores about 3-log compared with untreated samples after 21 days of storage. In addition, physicochemical and physiological properties of button mushroom were investigated during the storage period. Polyphenol oxidase and peroxidase enzymes residual activity of samples treated by 180 s of H2O2vapor+Ar plasma reduced 93.95% and 94.1% immediately after treatment, respectively. Furthermore, stiffness, color, phenolic and antioxidant compounds on the 21st day of storage improved compared with untreated samples. Novelty impact statement The mixture of hydrogen peroxide vapor with air as injecting gas plasma was able to inactivate Lacanicillium fungicola spores on the surface of button mushrooms. 180 s treatment with hydrogen peroxide vapor with argon gas plasma improved the color, firmness, phenolic and antioxidant content than control. The treatment by surface dielectric barrier plasma increased the shelf life of button mushroom by reducing the activity of lipid oxidation and PPO, POD enzymes residual activity.

Metabolomics and transcriptomics unravel the mechanism of browning resistance in Agaricus bisporus.

Agaricus bisporus is widely consumed on the world market. The easy browning of mushroom surface is one of the most intuitive factors affecting consumer purchase. A certain cognition on browning mechanism has been made after years of research. At present, people slow down the browning of mushrooms mainly by improving preservation methods. In addition, breeding is also a reliable way. In the production practice, we have identified some browning-resistant varieties, and we selected a browning-resistant variety to compare with an ordinary variety to reveal the resistance mechanism. Using transcriptomics and metabolomics, the differences in gene expression and metabolite levels were revealed, respectively. The results showed that differentially expressed genes (DEGs) like AbPPO4, AbPPO3 and AbPPO2 were differently expressed and these DEGs were involved in many pathways related to browning. The expression of AbPPO expression play an important role in the browning of A. bisporus and multiple PPO family members are involved in the regulation of browning. However, the resistance to browning cannot be judged only by the expression level of AbPPOs. For metabolomics, most of the different metabolites were organic acids. These organic acids had a higher level in anti-browning (BT) than easy-browning varieties (BS), although the profile was very heterogeneous. On the contrary, the content of trehalose in BS was significantly higher than that in BT. Higher organic acids decreased pH and further inhibited PPO activity. In addition, the BS had a higher content of trehalose, which might play roles in maintaining PPO activity. The difference of browning resistance between BS and BT is mainly due to the differential regulation mechanism of PPO.

3D Simulation and Artificial Neural Networks Application in the Diffusion Study of Champignon Mushroom/Solution Interface During the Salting

The influence of the film formed during the salting of champignon mushrooms with brine containing NaCl and KCl was modeled using the finite elements method (FEM). It was verified that the film formed on the mushroom surface had a greater influence in the static salting since the diffusion of the ions was 7.5-fold smaller in this system than in the stirred salting. The application of self-organizing maps showed that the ions diffusion along the surface of the solid presented a heterogeneous occurrence and depended on the region for both static and stirred salting. A direct relation was observed among the mushroom surface morphology, the salts diffusion behavior, and the film formation. In addition, the film was not completely extinguished in the stirred system, although it has a minimal influence as the film formation is also dependent on the biosolid surface.

Effects of Pre-Treatment Using Plasma on the Antibacterial Activity of Mushroom Surfaces.

Although non-thermal atmospheric pressure plasma is an efficient tool for preventing post-harvest microbial contamination, many studies have focused on the post-treatment of infected or contaminated foods. In this study, we examined the antimicrobial quality of mushrooms pre-treated with a non-thermal atmospheric pressure plasma jet (NTAPPJ) or plasma-treated water (PTW). The CFU (Colony Forming Unit) number of Escherichia coli inoculated on surfaces of mushrooms pre-treated with NTAPPJ or PTW was significantly reduced (about 60–75% for NTAPPJ and about 35–85% for PTW), and the reduction rate was proportional to the treatment time. Bacterial attachment and viability of the attached bacteria were decreased on NTAPPJ-treated mushroom surfaces. This may be caused by the increased hydrophilicity and oxidizing capacity observed on NTAPPJ-treated mushroom surfaces. In PTW-treated mushrooms, bacterial attachment was not significantly changed, but death and lipid peroxidation of the attached bacteria were significantly increased. Analysis of mushroom quality showed that loss of water content was greater in mushrooms treated with NTAPPJ compared to that in those with no treatment (control) and PTW treatment during storage. Our results suggest that pre-treatment with NTAPPJ or PTW can improve the antibacterial quality of mushroom surfaces by decreasing bacterial attachment (for NTAPPJ) and increasing bacterial lipid peroxidation (for both NTAPPJ and PTW).

Properties of plasma-activated water with different activation time and its effects on the quality of button mushrooms (Agaricus bisporus)

This study aimed to develop an underwater air plasma generator to produce plasma-activated water (PAW). The effect of plasma activation time on the physicochemical properties of PAW and the effect of thus-generated PAW on the postharvest quality of button mushrooms were investigated. The results showed that the pH value, electrical conductivity, and oxidation-reduction potential of PAW were significantly dependent on plasma activation time, while no obvious changes were observed in PAW temperature during the whole activation process. The PAW treatment effectively inactivated Escherichia coli cells on the surface of button mushrooms, with the bacterial reduction from 0.11 to 1.32 log10 CFU/g when the activation time increased from 5 to 25 min. Furthermore, PAW treatment delayed the browning process, extended the shelf life of mushrooms, and affected other quality attributes of mushrooms. Among all these groups with PAW treatment, the 20-PAW-treated groups showed the highest firmness and total soluble solid content, and the lowest browning index and relative electrical conductivity during the whole storage duration. Additionally, no significant changes were observed in the pH and 1,1-dipheny1-2-picrylhydrazyl radical-scavenging capacity among all groups.

The Efficiency of DBD Cold Plasma Pen Treatment on the Oyster Mushroom Bacterial Decontamination

Cold plasma provided bacterial inactivation role in food industry. In this study, the cold plasma play a crucial inactivation role when effectively reduces the bacteria colonies on oyster mushroom surface. By development of the dielectric barrier discharge-cold plasma pen (DBD-CPP) system, the mushroom surface was exposed to the cold plasma discharge with variable of exposure treatment time (0 min, 0.5 min, 1 min, 3 min and 5 min) with ~6 kV of power voltage and 5 SLM of atmospheric gas pressure flow rate. In order to identify the reduction of the microbial growth, isolation technique will be carry out by excising the mushroom sample into a suspension and serial dilution follows by identification of its colony morphologies and characteristics. Results screening shows increments of exposure treatment times up to 3 min shows none growth of bacteria colonies. This because the bacteria cell wall was disrupt and destruction by the plasma bombardment. Thus, this study able to extend the lifetime of the mushroom and produce a free microbial fresh mushroom by decontaminate the bacteria on the mushroom surface

The study of patterns of inhibition native microflora of raw materials under the influence of ultraviolet radiation with different processing intensity

Ultraviolet radiation has long proven itself as a technological process that allows you to reduce a significant amount or completely inhibit unwanted microorganisms, however, this technology is mainly used for disinfection of air and surfaces in industrial enterprises. The use of food processing with ultraviolet light is poorly developed, this is due to a number of limitations, one of which is the small depth of penetration of ultraviolet radiation. This circumstance introduces a number of restrictions and requires additional research for the active introduction of UV radiation in the food industry. The aim of the work: to study the dynamics of inhibition of native microflora of raw materials during UV treatment with various doses; to determine the degree of development of residual microflora during storage of UV-treated food products. Objects of research: model media containing native microflora of raw materials and fresh mushrooms. An improved UV treatment mode is proposed to reduce the surface injury of fresh mushrooms and ensure their microbiological stability of champignons during storage. The obtained results allowed us to establish the regularities of inhibition of native microflora on the surface of model media and fresh mushrooms depending on the distance to the UV radiation source, the time of irradiation, and the accumulated dose. It is noted that the dynamics of inhibition of native microflora on the surface of model media is not linear, and "Plateau" zones are marked. When developing a technology for processing fresh mushrooms, it is recommended to use a UV source with an accumulated radiation dose of 500 Dg/m2.

Modeling of Listeria monocytogenes survival and quality attributes of sliced mushroom (Agaricus bisporus) subjected to pulsed UV light

AbstractPulsed ultraviolet (PUV) light technology holds the potential for surface decontamination of foods. In this study, the survival of L. monocytogenes and some quality attributes (color, moisture, water activity, and antioxidant activity) of sliced mushrooms subjected to PUV light were modeled using data obtained from a previous study. Three mathematical models, log‐linear model, Weibull model, and log‐logistic model were used to describe the inactivation of L. monocytogenes with respect to fluence (J/cm2) at three treatment distances (5, 8, and 13 cm) from the quartz window of the PUV‐light system. Weibull model (R2adj: 0.8598–0.9820, root mean square error [RMSE]: 0.09–0.24) described the inactivation better compared to log‐linear model (R2adj: 0.7205–0.9072, RMSE: 0.22) and log‐logistic model (R2adj: 0.4871–0.7629, RMSE: 0.24–0.46). The survival curves of L. monocytogenes at all treatment distances showed upward concavity. These findings indicate that the survival of L. monocytogenes on sliced mushrooms subjected to PUV light follows a non‐linear trend, and the Weibull model may be a useful tool to predict the behavior of L. monocytogenes on mushroom surface subjected to PUV light. For the quality attributes, zero‐order kinetics (R2: 0.8500–0.9974, mean square error (MSE): 1.55*10−8–2.3124) described the changes slightly better compared to first‐order kinetics (R2: 0.8451–0.9974, MSE: 1.55*10−8–2.3867).Practical ApplicationsPulsed UV light is one of the most effective methods for the control of different pathogenic microorganisms on surfaces of food products. The parameters related to the kinetics of the inactivation of the pathogenic microorganisms in foods such as mushroom are of great importance to maintain food safety. Mathematical models provide practical information about not only tested variables but also untested ones. Process evaluation with mathematical models is useful to verify the effectiveness of the food safety applications. In this study, inactivation of L. monocytogenes on sliced mushroom surface was modeled using log‐linear, Weibull, and log‐logistic models. In addition, zero‐order and first‐order kinetics were applied to quality attributes of sliced mushroom in order to better understand the effect of pulsed UV light application.

Computer vision online measurement of shiitake mushroom (Lentinus edodes) surface wrinkling and shrinkage during hot air drying with humidity control

Abstract A new image processing method based on region segmentation was established for on-line measurement of surface wrinkling of shiitake mushrooms (Lentinus edodes) during hot air drying with four RH control methods. The relationship between RH change and the surface wrinkling and radial shrinkage of shiitake mushrooms during the drying process, as well as the effect on drying time and rehydration ratio (RR) were investigated. Compared with continuous dehumidification, maintaining relatively high RH can inhibit the case hardening of materials, while with prolonged drying time, resulting in more surface wrinkles, larger radial shrinkage, and lower RR. The optimized RH control method reduced the shrinkage, surface wrinkling, and drying time by continuous fanning in the later drying stage, but did not improve RR. For better rehydration characteristics in the meantime obtaining better appearance quality and shorter drying time, lower initial RH or its retention time in the early drying stage might be adopted.

Comparing Approaches for Capturing Bacterial Assemblages Associated with Symptomatic (Bacterial Blotch) and Asymptomatic Mushroom (Agaricus bisporus) Caps

Bacterial blotch is a complex of diseases, caused by Pseudomonas tolaasii and other Pseudomonas spp., whose growth may be influenced by other microorganisms associated with mushroom caps. The objectives of this work were to (i) compare methods for extracting DNA from mushroom caps to assess bacterial composition, and (ii) describe and quantify the composition of bacteria in and on symptomatic and asymptomatic mushroom caps. Symptomatic and asymptomatic mushrooms were collected at an organic farm in Pennsylvania and processed. Bacteria were removed from mushrooms by sonication to target surface-associated bacteria (washate), from whole mushrooms postsonication to target bacteria within or tightly adhering to the mushrooms (post-washate), or from whole macerated mushrooms to target all mushroom-associated bacteria in one sample (whole). Bacterial composition was determined through sequencing the V4 hypervariable region of the 16S rRNA gene on an Illumina MiSeq. Bacterial composition differed significantly based on mushroom health status and community removal method. Regardless of sampling approach, Proteobacteria and Bacteroidetes appeared as the most dominant phyla. In comparing the three extraction methods, higher Shannon diversity and Pielou’s evenness were observed for the washate and post-washate methods compared with whole mushroom sampling. Additionally, higher Shannon diversity, operational taxonomic unit richness, and Pielou’s evenness were found for the asymptomatic mushrooms when compared with symptomatic mushrooms. Pseudomonas spp. were overrepresented on mushroom surfaces (washate method), regardless of health status. This research made strides in describing the mushroom cap microbiome and established sampling methods that will allow researchers to target studies and isolation of specific bacterial taxa.

Kinetics of colour and texture changes of button mushrooms (Agaricus bisporus) coated with chitosan during storage at low temperature.

Kinetics of color and texture changes in coated button mushrooms were investigated as a function of coating agent's rate (1%, 2% and 3% w/v chitosan). The inner and outer surface colours of mushrooms in terms of CIELAB parameters L*, a*, b*, C*, ° h, ∆E, and Browning Index (BI), and their textural properties in terms of firmness were evaluated. The color values on both sides of the mushrooms except for L* values increased and their firmness decreased with the coating treatment. The color changes of the inner and outer surface of mushrooms and their texture changes followed zero-order reaction models with higher R2 (0.9987-0.9999) and lower RMSE (4.8448 x 10-5-1.6690) and χ2 values (3.9120 x 10-9-4.6425). The 2% chitosan solution was determined to be the most effective coating agent among the coating agents used to extend the post-harvest shelf life by optimally preserving the color parameters of the mushrooms together with their texture properties.

Low Temperature (15 °C) Reduces Bacterial Diversity and Prolongs the Preservation Time of Volvariella volvacea.

Straw mushroom (Volvariella volvacea) is the most commonly cultivated edible fungus in the world, but the challenges associated with the preservation have limited its marketability. Microbiology, especially bacteria, play a key role in the deterioration of food, this study aimed to reveal the succession of the bacterial community on the surfaces of V. volvacea fruit bodies under different temperature conditions. We amplified 16S rRNA genes of V4 regions, obtained the bacterial species information by using high-throughput sequencing technology, and analyzed the effects of environmental temperature and preservation time on bacterial communities. The relative abundances of Firmicutes, Bacilli, and Bacillales increased significantly when straw mushrooms began to rot. Furthermore, the relative abundances of Paenibacillus, Lysinibacillus and Solibacillus, which belong to Bacillales, increased with the decay of straw mushroom. The Shannon and Simpson indices of V. volvacea stored at 30 °C were significantly higher than those of V. volvacea stored at 15 °C, which indicates that a high temperature contributes to the improvement in the species diversity. According to the linear discriminant analysis (LDA) effect size (LEfSe) results, the number of biomarkers in the 30 °C group (32, 42.11%) was significantly higher than that in the 15 °C group (17, 22.37%), indicating that a high temperature has a clustering effect on some bacterial communities. A Spearman correlation analysis showed that Pseudomonas, Stenotrophomonas and Solibacillus promoted the decay of straw mushroom. In conclusion, a high temperature increases the bacterial diversity on the straw mushroom surfaces and has a clustering effect on the bacterial communities. The bacterial community consisting of Firmicutes, Bacilli, Bacillales, Paenibacillus, Lysinibacillus, Pseudomonas, Stenotrophomonas and Solibacillus could promote the decay of straw mushroom, so new preservation materials research can focus on inhibiting anaerobic and decay-causing bacteria to prolong preservation time.