Related Experiment Video

Updated: Jun 12, 2026

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy
10:03

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy

Published on: November 30, 2017

Microwave inactivation of Bacillus atrophaeus spores in healthcare waste

E A Oliveira1, N G P Nogueira, M D M Innocentini

  • 1Postgraduate Program in Environmental Technology, University of Ribeirão Preto, Rua José Bonifácio, 799 13560-610, São Carlos, SP, Brazil.

Waste Management (New York, N.Y.)
|June 24, 2010
PubMed

Insights

Microwave treatment effectively inactivates Bacillus atrophaeus spores in healthcare waste. Optimized conditions using moisture and surfactant enhance heating, revealing both thermal and radiation effects on spore inactivation.

Area of Science:

  • Environmental Science
  • Microbiology
  • Engineering

Background:

  • Healthcare waste poses significant biohazard risks.
  • Autoclaving is a common sterilization method, but alternative methods are explored.
  • Bacillus atrophaeus spores are used as a biological indicator for sterilization efficacy.

Purpose of the Study:

  • To investigate the efficacy of microwave irradiation for inactivating Bacillus atrophaeus spores in healthcare waste.
  • To determine the influence of waste moisture, surfactant, power density, and time on heating and inactivation.
  • To model the inactivation kinetics using Chick's and Arrhenius laws.

Main Methods:

  • Laboratory-scale microwave processing of inoculated healthcare waste.
  • Varied waste moisture (40-60%), surfactant presence, power density (100-200 W/kg), and exposure time (5-40 min).
  • Kinetic analysis using Chick's and Arrhenius laws, fitting experimental data with the least squares method.

Main Results:

  • Optimized heating conditions identified based on moisture and surfactant use.
  • Inactivation of Bacillus atrophaeus spores was dependent on time and power density.
  • Activation energies (9203-5782 J/mol) and pre-exponential factor (0.23 min⁻¹) were determined.
  • Activation energy decreased with increased power per waste mass.

Conclusions:

  • Microwave processing is a viable method for healthcare waste sterilization.
  • Both thermal and non-thermal (radiation-inherent) effects contribute to spore inactivation.
  • Kinetic parameters allow prediction of inactivation levels for Bacillus atrophaeus spores.

More Related Videos

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate08:25

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate

Published on: April 6, 2022

A Tuberculosis Molecular Bacterial Load Assay (TB-MBLA)10:41

A Tuberculosis Molecular Bacterial Load Assay (TB-MBLA)

Published on: April 30, 2020

Related Concept Videos

Methods of Sterilization I: Physical Methods01:29

Methods of Sterilization I: Physical Methods

As used in a healthcare facility, sterilization destroys all microorganisms through physical or chemical methods. The physical method includes steam, dry heat, boiling water, and radiation.
Steam sterilization uses non-toxic, low-cost moist heat in the form of saturated steam under pressure, which is fast, microbicidal, and sporicidal, and quickly warms and penetrates fabrics. Autoclaves, or steam sterilizers, expose each item to direct steam contact for a predetermined time at the necessary...
Physical Methods for Controlling Microbial Growth: Radiation and Filtration01:26

Physical Methods for Controlling Microbial Growth: Radiation and Filtration

Radiation and filtration are essential tools for microbial control, targeting microorganisms through distinct mechanisms. Radiation eliminates microbes by damaging their DNA, either killing them or inhibiting their growth. Based on wavelength, radiation is classified into two types: nonionizing and ionizing radiation.Non-ionizing radiation, such as UV radiation (200–400 nm), is absorbed by DNA, causing defects that effectively disinfect surfaces, air, and water, including safety cabinets.
Physical Methods for Controlling Microbial Growth: Temperature01:23

Physical Methods for Controlling Microbial Growth: Temperature

Heat is a widely used method to control microbial growth by targeting and denaturing cellular proteins, thereby killing or inactivating microbes. This method's effectiveness is quantified using parameters such as the thermal death point (TDP), thermal death time (TDT), and decimal reduction time (D value). TDP represents the lowest temperature at which all microorganisms in a liquid suspension are eliminated within 10 minutes, whereas TDT is the time necessary to achieve sterilization at a...
Methods for Controlling Microbial Growth01:29

Methods for Controlling Microbial Growth

Microbial growth control refers to various methods employed to inhibit, reduce, or eliminate microorganisms to ensure safety and hygiene across different settings. These methods are categorized based on the target environment and the level of microbial control required.Biocides are versatile agents designed to control microorganisms by either inhibiting their growth or outright killing them. These agents work through various physical, chemical, mechanical, or biological mechanisms. The...
Methods of Sterilization II: Chemical Methods01:30

Methods of Sterilization II: Chemical Methods

In healthcare, the chemical method of sterilization uses chemical sterilants to treat surgical instruments and medical supplies to help prevent the transmission of infectious pathogens to patients. Due to heat sensitivity, most medical supplies and equipment should not be exposed to high temperatures. These parts include rubber, plastic, glass, and other similar elements.
Using chemical sterilization rather than heat to clean out equipment is recommended. It eradicates and removes all bacteria,...
Chemical Agents for Microbial Control01:27

Chemical Agents for Microbial Control

Chemicals play important roles in controlling microbial growth by targeting microbial structures and functions as sanitizers, antiseptics, disinfectants, and sterilants.Alcohols are commonly used sanitizers, effectively disrupting lipid membranes, which compromises cell integrity. They are also used as antiseptics and disinfectants due to their rapid action and versatility.Phenols and their derivatives phenolics , known for denaturing proteins and disrupting cell membranes, are particularly...