Chitosan utilized for bacterial preparation for scanning electron microscopy.

Area of Science:

• Microscopy
• Microbiology
• Materials Science

Background:

• Scanning electron microscopy (SEM) is vital for visualizing bacterial morphology.
• Current polylysine (PLL) coating methods can induce artificial changes in bacterial structure.
• Developing improved sample preparation techniques is essential for accurate SEM analysis.

Purpose of the Study:

• To evaluate chitosan (CS) as an alternative coating agent for bacterial sample preparation for SEM.
• To compare the efficacy of CS coating against the conventional PLL method.
• To determine optimal parameters for CS-based bacterial sample preparation for SEM.

Main Methods:

• Coverslips were coated with 0.025% chitosan (CS) and compared with polylysine (PLL) coated coverslips.
• Bacterial binding ability and morphology were assessed using SEM and transmission electron microscopy (TEM).
• Four bacterial strains were used to evaluate differences in SEM imaging after 30 minutes of binding time.

Main Results:

• CS coating demonstrated satisfactory bacterial binding, comparable to PLL.
• SEM images of bacteria on CS-coated coverslips showed clearer surface textures than those on PLL.
• TEM confirmed that CS preserved bacterial envelope integrity, unlike PLL which caused deformation.
• CS coating resulted in less shrinkage and better preservation of rod-shaped bacteria length compared to PLL.

Conclusions:

• Chitosan (CS) is a cost-effective and superior alternative to polylysine (PLL) for preparing bacteria for SEM.
• CS coating minimizes artificial morphological alterations, leading to more accurate bacterial imaging.
• Optimal parameters include using a 0.025% CS solution, a 30-minute binding time, and standard fixation, dehydration, and drying procedures.