Sterilizer Research Articles

Updated review of wet pack complications in pulse vacuum pressure steam sterilisation processes in central sterile supply departments.

The quality of sterilisation and disinfection in a central sterile supply department is directly related to the quality of the hospital services and the patients' safety. Wet packs occasionally occur following the process of pressure steam sterilisation; reducing this occurrence is an important issue. Therefore, the causes of wet pack following sterilisation were analysed to identify the influencing factors and suggest improvements to prevent its occurrence. Understanding the sterilisation process and possible causes of exposure helps with risk assessment and identifying necessary corrective measures.

Environmental and economic assessments of industry-level medical waste disposal technologies – A case study of ten Chinese megacities

Medical waste (MW) is exploding due to the COVID-19 pandemic, posing a significant environmental threat, and leading to the urgent requirement for affordable and environmentally friendly MW disposal technologies. Prior research on individual MW disposal plants is region-specific, applying these results to other regions may introduce bias. In this study, major MW disposal technologies in China, i.e., incineration technologies (pyrolysis incineration and rotary kiln incineration), and sterilization technologies (steam sterilization, microwave sterilization, and chemical disinfection) with residue landfill or incineration were analyzed from an industry-level perspective via life cycle assessment (LCA), life cycle costing (LCC) and net present value (NPV) methods. Life cycle inventories and economic cost data for 4–5 typical companies were selected from 128 distinct enterprises and academic sources for each technology. LCA results show that microwave sterilization with residue incineration has the lowest environmental impact, emitting only 480 kg CO2 eq. LCC and NPV analyses indicate that steam sterilization with landfilling is the most economical, yielding revenues of 1,210 CNY/t and breaking even in the first year. Conversely, pyrolysis and rotary kiln incineration break even between the 4th and 5th years. Greenhouse gas emissions from the MW disposal in ten cities with the largest MW production in 2020 increased by 7% over 2019 to 43,800 tons and other pollutants increased by 6% to 12%. Economically, Shanghai exhibits the highest cost-effectiveness, while Nanjing delivers the lowest. It can be observed that the adoption of optimal environmental technologies has resulted in a diminution of greenhouse gas emissions by 279,000 tons and energy conservation of 1.76 billion MJ.

Heat penetration and quality attributes of superheated steam sterilization (SHS) home meal replacement (HMR) meat products stew

Retort sterilization (RTS) is essential for the production of shelf-stable home meal replacement (HMR)-type Korean foods. However, the thermal abuse caused by excessive retort processing can result in quality degradation. Short processing times can minimize quality degradation and nutritional loss during sterilization. The potential of superheated steam sterilization (SHS) for producing shelf-stable HMR was investigated. The effect of SHS at 140 °C on HMR meat products stew was compared with that of RTS. SHS allowed a rapid temperature increase in the sausages and spam. In the sterilization equivalence of sausage, SHS at 140 °C and 1 s showed the F0 value of 34.7 ± 5.9 which could sufficiently satisfy the microbial safety standard of F0 values at 7–10 min. Thermal doses of SHS treated sausage was 97 ± 9 k°C·s which has lesser values (119 ± 9 k°C·s) than that of RTS. The sausage hardness after SHS was 107.7 ± 13.3 N, which has lower thermal degradation than the 78.9 ± 7.1 N observed after RTS. This study demonstrates the potential of SHS treatment for maintaining the quality of sterilized HMR products.

Evaluation of an early-stage prototype polyurethane femoral head implant for hip arthroplasty

IntroductionThi study evalautes a new bone-preserving femoral head cover that mimics the articular cartilage of the femoral head. MethodsA specially developed polyurethane (PU) was evaluated in biocompatibility (cytotoxicity test) and mechanical response to tensile loading. In the cytotoxicity test, steam sterilized (SS) and ethylene oxide sterilized (EtO) PU samples were incubated separately in a cell culture medium. The seeded cell line MG-63 was then added to these sample-incubated cell culture mediums. One negative control group and one positive control group were also evaluated. The cells in each group were cultured for seven days before being quantified using the alamarBlue assay. In the mechanical test, the femoral head cover implants were separated into three groups of three samples. Each group represented a different implant insertion idea: direct insertion (uc sample) and another two insertion modes (is and ss samples) representing implants with enclosure mechanisms. The test consisted of distance-controlled cyclic tensile loadings followed by a failure test. ResultsThe cytotoxicity test results show no significant difference in fluorescence intensity between the negative control, the three SS groups, and one EtO group (P > 0.05). However, the other two EtO groups exhibit significantly lower fluorescence intensity compared with the negative control (P < 0.05). In the mechanical test, the is samples have the highest cyclic loading force at 559.50 ± 51.41 N, while the uc samples exhibit the highest force in the failure test at 632.16 ± 50.55 N. There are no significant differences (P > 0.05) among the uc, is, and ss groups in terms of stiffness. ConclusionThe cytotoxicity test and the mechanical experiment provide initial assessments of the proposed PU femoral head cover implant. The evaluation outcomes of this study could serve as a foundation for developing more functional design and testing methods, utilizing numerical simulations, and developing animal/clinical trials in the future.

Kilogram-Scale Synthesis of Extremely Small Gadolinium Oxide Nanoparticles as a T1-Weighted Contrast Agent for Magnetic Resonance Imaging.

Magnetic resonance imaging contrast agents are frequently used in clinics to enhance the contrast between diseased and normal tissues. The previously reported poly(acrylic acid) stabilized exceedingly small gadolinium oxide nanoparticles (ES-GdON-PAA) overcame the problems of commercial Gd chelates, but limitations still exist, i.e., high r2/r1 ratio, long blood circulation half-life, and no data for large scale synthesis and formulation optimization. In this study, polymaleic acid (PMA) is found to be an ideal stabilizer to synthesize ES-GdONs. Compared with ES-GdON-PAA, the PMA-stabilized ES-GdON (ES-GdON-PMA) has a lower r2/r1 ratio (2.05, 7.0 T) and a lower blood circulation half-life (37.51min). The optimized ES-GdON-PMA-9 has an exceedingly small particle size (2.1nm), excellent water dispersibility, and stability. A facile, efficient, and environmental friendly synthetic method is developed for large-scale synthesis of the ES-GdONs-PMA. The weight of the optimized freeze-dried ES-GdON-PMA-26 synthesized in a 20L of reactor reaches the kilogram level. The formulation optimization is also finished, and the concentrated ES-GdON-PMA-26 formulation (CGd=100mm) after high-pressure steam sterilization possesses eligible physicochemical properties (i.e., pH value, osmolality, viscosity, and density) for investigational new drug application.

A simulation study on enhancing sterilization efficiency in medical plastics through gamma radiation optimization

Gamma radiation is progressively emerging as an effective method to enhance the sterilization efficiency of medical plastics including Polyvinyl chloride (PVC). The parameters of the radiation facility will affect the efficiency of radiation sterilization. To investigate these effects, we simulate the gamma radiation sterilization performance of PVC material sample using Monte Carlo Method. The simulation results indicated that compared with the sterilization time of 20–90 min from high-temperature steam sterilization of medical waste, by optimizing the parameters of the model radiation facility, the radiation sterilization time can be reduced to 6.61 min. The optimized model facility parameters are as follows: the gamma photon energy is 1.25 MeV, the model space is 300 × 300 × 300 cm3, the reflective layer material is concrete and its thickness is 8 cm, the PVC sample layer area is 100 × 100 cm2, the distance between the radiation source and the PVC sample layer is 150 cm, the energy deposition in the bottom layer of the PVC sample layer is 1.31315 × 10–6 MeV/g. This study offers a potentially feasible way for PVC sterilization, while also providing a crucial reference for the further promotion and application of radiation sterilization technology.

Effect of wetting and fungal degradation on the withdrawal capacity of stainless-steel screws in radiata pine

The effects of exposure to two decay fungi on the withdrawal capacity of stainless-steel screws inserted in the face and end grain of radiata pine specimens were assessed. Wetting followed by steam sterilization significantly increased capacity by 55–65%. Exposure to a brown (Fomitopsis ostreiformis) or white rot fungus (Pycnoporus coccineus) over 25 weeks was associated with 81–83% and 24–42% losses in withdrawal capacity, respectively. Comparison of experimental results with those predicted from design codes (Australia, Europe, US) showed an overestimation of the screw withdrawal capacity for the control specimens and highlighted the risk of strength degradation, especially in those specimens affected by brown rots.

The Surgical Instrument Sterilization Process: What Every Surgeon Should Know.

» The phases of the sterilization process for surgical equipment are cleaning, disinfection, and sterilization.» Following manufacturer and regulatory guidelines will minimize contamination throughout the sterilization process.» Immediate use steam sterilization, when used appropriately, is a reasonably safe option to be used at the discretion of the operating surgeon.

Risk of disease transmission to patients from “contaminated” surgical instruments and immediate use steam sterilization

BackgroundThere are several sources of pathogens that cause surgical site infections (SSI) to include the patients endogenous microflora and exogenous sources (e.g., air, surfaces, staff, surgical equipment). MethodsWe searched the published English literature (Google, Google Scholar, PubMed) for articles on reprocessing surgical instruments, effectiveness of sterilization methods, microbial load on surgical instruments, frequency of “contaminated” instruments, and the infection risk associated with “contaminated” surgical instruments and immediate use steam sterilization. ResultsThere is substantial redundancy in instrument reprocessing to include: even if a patient was exposed to a “contaminated” instrument, the decontamination and sterilization process would have removed and/or inactivated the contaminating pathogens due to the exceptional effectiveness of the manual and mechanical cleaning (i.e., washer-disinfector) and the remarkable robustness of sterilization technology; and the low-level of microorganisms on surgical instruments after use and before cleaning. ConclusionsA critical review of the literature suggests that the risk of acquiring an SSI from instruments used in surgery is essentially zero if the sterilization cycle is validated.

Visible light-mediated cross-linking of injectable gellan gum hydrogels embedding human chondrocytes

Gellan gum, a polysaccharide with structural similarities to glycosaminoglycans, is gaining attention in cartilage tissue engineering. It can be chemically modified with methacrylic moieties to produce a photo-crosslinkable formulation, called methacrylated gellan gum (GGMA), envisaging the injection and the in situ cross-linking through light on the cartilage surface.This study aimed to investigate the visible light cross-linking of GGMA, underlying the impact of steam sterilization on its chemical and rheological properties and cross-linking efficiency. After an initial assessment of the sterilization effects, we evaluated a combination of hydrogel concentrations (1 and 2 % w/v), ruthenium/sodium persulfate concentrations (0.1/1, 0.2/2 and 0.5/5 mM ratios), and light exposure times (30, 60 and, 120 s). The formulations with the lowest sol fraction were characterized for mechanical and showed self-healing properties. Biological characterization on encapsulated chondrocytes in hydrogels showed high cell viability with increased metabolic activity over two weeks. The expression of genes encoding collagen type II and cartilage oligomeric matrix protein was upregulated in the softer formulation (E = 0.95 ± 0.48 kPa) composed of 2 % w/v GGMA, 0.1/1 mM Ru/SPS, and photo-crosslinked for 60 s. These findings represent an interesting overview of the potential application of visible-light crosslinked GGMA in the clinical scenario to treat cartilage defects.

The effect of different sterilization methods on the shelf life and physicochemical indicators of fermented pork jerky

BackgroundTo determine the effect of different sterilization methods on shelf life and physicochemical parameters of fermented pork jerky.MethodsVarious sterilization techniques, including boiling, pasteurization, medium-temperature steam sterilization, high-temperature steam sterilization, ultrasonic sterilization, and ultraviolet sterilization, were employed in this study to treat vacuum-sealed fermented pork jerky. Changes in microbial populations, physicochemical parameters, and sensory evaluations were monitored throughout the storage period.ResultsThe results indicated the presence of Staphylococcus aureus on the 24th, 21st, 33rd, 24th, 18th, and 15th days in pork jerky subjected to boiling (100°C, 20 min), pasteurization (85°C, 15 min), medium-temperature steam sterilization (105°C, 0.5 Pa, 30 min), high-temperature steam sterilization (121°C, 1.0 Pa, 20 min), ultrasonic sterilization (480 W, 30 kHz, 30 min), and ultraviolet sterilization (254 nm, 100 W/m2, 60 min), respectively. Coliforms, salmonella, and Shigella were not detected in any group during storage. The medium-temperature steam sterilization method yielded the most favorable microbiological results, with an aerobic plate count of less than 1.0 lg CFU/g. However, other physicochemical parameters and sensory evaluations were moderate, with total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS) measuring 14.023 mg N/100 g and 0.427 mg MDA/kg, respectively, remaining within acceptable limits.ConclusionTherefore, considering microbiological indicators as the primary determinant of shelf life and taking into account other physicochemical parameters, the medium-temperature steam sterilization method was identified as the most suitable approach for extending the shelf life of fermented pork jerky while preserving its flavor.

Research on the Influence of Backfilling Mining in an Iron Mine with Complex Mining Conditions on the Stability of Surface Buildings

The safe and efficient extraction of ore bodies under buildings contributes to the continued exploitation and utilization of mineral resources. To effectively reduce the mining-induced disturbance caused to surface buildings, the Vertical Crater Retreat (VCR) delayed backfilling method was applied at the Wuji iron mine according to mining theory and engineering experience, and the surface deformation under buildings was investigated through numerical simulation and on-site monitoring. The results show that stress concentration occurs at the top of the ore body and in surrounding rocks between ore veins, and the direction of the principal stress coincides with that of the main bearing capacity of the rock mass. With the increasing distance between the surrounding rock and the ore body, the stress disturbance in the surrounding rock attenuates gradually. The surface subsidence and deformation caused by ore mining exhibits the same northwest trend as the strike of the ore body, and the surface deformation in the X direction is greater than that in the Y direction. The surface deformation of the mining area near the 1# air shaft, Wuji village, steam autoclave workshop of the brick factory, and 1# substation is relatively large, while the surface subsidence, horizontal deformation, inclination, and curvature are all smaller than the critical values allowed for buildings and structures. This research provides a theoretical basis and engineering guidance for the prevention and control of surface deformation during mining under buildings and structures.

Effect of Low Heat Steam Sterilization on the Volumetric Stability of Three Different 3D Printing Materials for Dental Implant Surgical Templates: An in vitro Study

Background: Computer-guided surgical templates are considered critical instruments and are proposed to be sterilized before surgery. However, steam heat sterilization process may result in volumetric changes in the acrylic resin materials and this may compromise the accuracy of the drilling process during surgery. Objective: The aim of this in vitro study was to investigate the effect of steam heat sterilization on the volumetric and morphological dimensions of 3D printed surgical guides that could affect the accuracy of guided implant surgery. Methods: A total of fifteen templates of the same size and shape were printed from three different resin materials (five templates from each material) based on digital data of a clinical case previously planned with a special implant planning software. Following the printing procedure, all templates were digitally scanned using an intraoral scanner before and after steam heat sterilization at 121°C for 20 minutes. The scan data were saved in STL files and volumetric and morphological changes were evaluated before and after sterilization process by using appropriate software. Results: The results showed dimensional alterations within the three tested materials, before and after the sterilization process. Mean percentage of volumetric change was -1.53% for Visijet, 0.50% for MED610 and 1.9% for eResin. A larger deformation of the surgical guides at the sleeve and buccal wire areas was also observed. Conclusion: We can conclude that low steam heat sterilization seems to affect differently the three investigated implant template materials. Visijet and eResin showed a significant difference between the initial and the final volume of the surgical guides. This could possibly decrease the accuracy of computer guided surgery.

Evolution of Morphology and Distribution of Salt Crystals on a Photothermal Layer during Solar Interfacial Evaporation.

Solar interfacial evaporation (SIE) by leveraging photothermal conversion could be a clean and sustainable solution to the scarcity of fresh water, decontamination of wastewater, and steam sterilization. However, the process of salt crystallization on photothermal materials used in SIE, especially from saltwater evaporation, has not been completely understood. We report the temporal and spatial evolution of salt crystals on the photothermal layer during SIE. By using a typical oil lamp evaporator, we found that salt crystallization always initiates from the edge of the evaporation surface of the photothermal layer due to the local fast flux of the vapor to the surroundings. Interestingly, the salt crystals exhibit either compact or loose morphology, depending on the location and evaporation duration. By employing a suite of complementary analytical techniques of Raman and infrared spectroscopy and temperature mapping, we followed the evolution and spatial distribution of salt crystals, interfacial water, and surface temperature during evaporation. Our results suggested that the compact crystal structure may emerge from the recrystallization of salt in an initially porous structure, driven by continuous water evaporation from the porous and loose crystals. The holistic view provided in this study may lay the foundation for effective strategies for mitigation of the negative impact of salt crystallization in solar evaporation.

Integrated life cycle assessment with data envelopment analysis for enhancing medical waste management during a public health crisis

The generation of medical waste (MW) is expected to increase significantly during a public health crisis, such as COVID-19, which presents serious challenges to subsequent MW treatment systems. However, little research has been investigated into the sustainability of MW management during emergency crisis. It is crucial to explore the variations brought about by the pandemic and identify proper measures to improve inadequate treatment efficiencies to handle the increased MW burdens, but, this has not been addressed yet. This study developed an integrated model of life cycle assessment (LCA) with data envelopment analysis (DEA) to examine and enhance the efficiency of MW management during a pandemic, with a focus on Wuhan City, Hubei Province, and China. The findings showed that during the peak of the pandemic, environmental and economic impacts of MW treatment were 1.3–5.4 times and 1.9–5.9 times higher, respectively. These variations were mostly caused by steam sterilization to create a high-temperature environment, emphasizing the need to replace conventional fuels with sustainable sources. The LCA-DEA model identified movable organic Rankine cycle (ORC) incinerator as the most efficient option, achieving a full score of 1.0 for both pure technical efficiency and scale efficiency. Additionally, the model quantified potential reductions in environmental impacts, such as global warming and terrestrial acidification, to enhance management efficiency of inadequate strategies. The findings of this study not only reveal variations brought about by the pandemic but also provide effective measures to enhance MW management efficiencies under emergency situations, which can indicate policymakers and practitioners on how to improve MW management during public health crisis.

Chondrogenic Potential of Human Adipose-Derived Mesenchymal Stromal Cells in Steam Sterilized Gelatin/Chitosan/Polyvinyl Alcohol Hydrogels.

Cross-linked polymer blends from natural compounds, namely gelatin (Gel), chitosan (CS), and synthetic poly (vinyl alcohol) (PVA), have received increasing scrutiny because of their versatility, biocompatibility, and ease of use for tissue engineering. Previously, Gel/CS/PVA [1:1:1] hydrogel produced via the freeze-drying process presented enhanced mechanical properties. This study aimed to investigate the biocompatibility and chondrogenic potential of a steam-sterilized Gel/CS/PVA hydrogel using differentiation of human adipose-derived mesenchymal stromal cells (AD-hMSC) and cartilage marker expression. AD-hMSC displayed fibroblast-like morphology, 90% viability, and 69% proliferative potential. Mesenchymal profiles CD73 (98.3%), CD90 (98.6%), CD105 (97.0%), CD34 (1.11%), CD45 (0.27%), HLA-DR (0.24%); as well as multilineage potential, were confirmed. Chondrogenic differentiation of AD-hMSC in monolayer revealed the formation of cartilaginous nodules composed of glycosaminoglycans after 21 days. Compared to nonstimulated cells, hMSC-derived chondrocytes shifted the expression of CD49a from 2.82% to 40.6%, CD49e from 51.4% to 92.2%, CD54 from 9.66 to 37.2%, and CD151 from 45.1% to 75.8%. When cultured onto Gel/CS/PVA hydrogel during chondrogenic stimulation, AD-hMSC changed to polygonal morphology, and chondrogenic nodules increased by day 15, six days earlier than monolayer-differentiated cells. SEM analysis showed that hMSC-derived chondrocytes adhered to the surface with extended filopodia and abundant ECM formation. Chondrogenic nodules were positive for aggrecan and type II collagen, two of the most abundant components in cartilage. This study supports the biocompatibility of AD-hMSC onto steam-sterilized GE/CS/PVA hydrogels and its improved potential for chondrocyte differentiation. Hydrogel properties were not altered after steam sterilization, which is relevant for biosafety and biomedical purposes.

Effect of ScCO2 on the decontamination of PECs-based cryogels: A comparison with H2O steam and H2O2 nebulization methods

Biopolymers present ideal properties to be used in wound dressing solutions. By mixing two oppositely charged macromolecules it is possible to form polyelectrolyte complex (PEC) based cryogels using lyophilization. Their application in the biomedical field is limited due to their sterilization requirements, as conventional methods compromise their physicochemical properties. ScCO2 appears as an alternative method for decontamination. This work assessed several cryogel PEC formulations, chitosan-pectin, gelatine-xanthan gum and alginate-gelatine. PEC formation was confirmed by FTIR and rheological analysis. While steam sterilization compromised cryogels’ chemical and morphological properties, decontamination with scCO2 proved to be a promising method for decontamination of PEC-cryogels, because, similarly to what is observed with hydrogen peroxide, it does not compromise their physicochemical properties.

Effect of steam sterilisation on physico-chemical properties of antibacterial covalently cross-linked ε-polylysine/hyaluronic acid hydrogels

Sterilisation of implantable biomaterials such as hydrogels remains a key step towards their clinical translation. Standard sterilisation methods can significantly alter hydrogels' physicochemical and biological performance. Previously, we developed composite hydrogels based on ε-polylysine (ε-PL) and hyaluronic acid (HA). The developed hydrogels demonstrated promising antibacterial activity and in vitro cell viability and their variable properties depending on the chosen ε-PL to HA ratio. In this study, we fabricated a series of chemically cross-linked ԑ-PL/HA hydrogels with expanded ԑ-PL to HA mass ratios.Using small-angle X-ray scattering (SAXS), we unravelled the topological differences between physically and chemically crosslinked hydrogels. We then selected the chemically crosslinked hydrogel ԑ-PL/HA series of 60:40 wt%, 70:30 wt%, and 80:20 wt% ratios, with similar network topologies, to evaluate the impact of steam sterilisation on their physicochemical and viscoelastic properties. The antibacterial activity of the sterilized hydrogels was also evaluated against Gram-negative and Gram-positive bacteria. Our results showed that steam sterilisation minimally affects structure and physicochemical properties of ԑ-PL/HA hydrogels. Furthermore, the developed hydrogel ԑ-PL/HA series of 60:40 wt%, 70:30 wt%, and 80:20 wt% ratios showed pronounced antibacterial activity against Gram-negative and Gram-positive pathogenic bacteria. We expect our results will contribute to the growing understanding of using sterilisation methods for antibacterial hydrogels that have the potential for wider tissue engineering applications.

Evaluation of hernia surgical meshes sterilised with ethylene oxide for adoption under UK regulations

BackgroundLow-cost meshes (LCM) have been successfully used in low-income countries (LIC) over the past decades, demonstrating comparable surgical outcomes to commercial meshes at a fraction of the cost. However, LIC sterilisation standards (autoclave sterilisation at 121 °C) do not meet UK regulations for medical devices, which require either ethylene oxide (EO) sterilisation or steam sterilisation at 134 °C. Therefore, the aim of this study was to sterilise UK LCM and characterise their mechanical properties and in vitro biocompatibility to verify whether EO sterilisation causes changes in the mechanical properties and biocompatibility of LCM.MethodsEO sterilised LCM were used. Uniaxial tensile tests were performed to measure mechanical properties. Biocompatibility was measured through viability and morphology of Human Dermal Fibroblasts (HDFs) cultured in mesh-conditioned media, and by calculating the metabolic activity and proliferation of HDFs attached on the meshes, with alamarBlue assay.ResultsBreak stress of LCM1 was significantly higher than LCM2 (p < 0.0001), while Young’s modulus of LCM1 was significantly lower than LCM2 (p < 0.05) and there was no significant difference in break strain. Viability and morphology showed no significant difference between LCM and control. Attachment and proliferation of HDFs on LCM showed a better proliferation on LCM2 than LCM1, with values similar to the control at the final time point.ConclusionsWe demonstrated that EO sterilisation affects LCM mechanical properties, but they still have values closer to the native tissues than the commercially available ones. We also showed that in vitro biocompatibility of LCM2 is not affected by EO sterilisation, as HDFs attached and proliferated on the mesh, while EO affected attachment on LCM1. A more detailed cost analysis of the potential savings for healthcare systems around the world needs to be performed to strengthen the cost-effectiveness of this frugal innovation.

Sterilization and Substrate Level Optimization for Improving Yield and Biological Efficiency of Paddy Straw Mushroom

A study was conducted to determine the impact of surface sterilization techniques and different quantity of bed substrate on yield and biological efficiency in paddy straw mushroom cultivation. Among the various combinations of sterilization methods i.e., Plain water, Plain water + Calcium oxide @ 2%, Plain water + Bavistin 75 ppm &amp; Formalin 500 ppm and steam sterilization 55 for ½ hour respectively tried on paddy straw substrate, Maximum yield and biological efficiency (1966 g &amp; 15.2%) was obtained. To evaluate the biological efficiency of different layers and quantity of straw in bed method of cultivation i.e., 5 layers (4.0 kg), 4 layers (3.2 kg), 3 layers (2.4 kg) and 2 layers (1.6 kg) were tested. on biological efficiency four layers bed proved its superiority among all the number of substrate layers experimented, and gave highest biological efficiency (17.6%) followed by three layers and five layers (15.2%) and (14.5%) respectively. Two layers of bed (1.6 kg) were found to be less suitable and gave 13.8% biological efficiency of paddy straw. Maximum average weight of sporophores (24.21 g) was observed from four layers of beds followed by three layers and five layers (20.88 g) and (19.98 g) respectively. Smaller size sporophores were noticed in two layers of beds (14.18 g).