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Nakamura, S. Bioshell Calcium Oxide Water. Encyclopedia. Available online: (accessed on 07 December 2023).
Nakamura S. Bioshell Calcium Oxide Water. Encyclopedia. Available at: Accessed December 07, 2023.
Nakamura, Shingo. "Bioshell Calcium Oxide Water" Encyclopedia, (accessed December 07, 2023).
Nakamura, S.(2020, August 17). Bioshell Calcium Oxide Water. In Encyclopedia.
Nakamura, Shingo. "Bioshell Calcium Oxide Water." Encyclopedia. Web. 17 August, 2020.
Bioshell Calcium Oxide Water

Bioshell calcium oxide (BiSCaO) exhibits broad microbicidal activity for instance. In this study, we examined possible utility of BiSCaO Water for that purpose. The produced BiSCaO Water contained nanoparticles, and was colorless and transparent, with a pH > 12.7. In vitro assays demonstrated that BiSCaO Water eliminated more than 99.9% of influenza A (H1N1) and Feline calicivirus, Escherichia coli within 15 min for instance. BiSCaO Water exhibit excellent disinfection activities against pathogenic bacteria and viruses (including both enveloped and nonenveloped viruses).

calcium oxides deodorization disinfection heated scallop-shell powder microbicidal activity

1. Bioshell calcium oxide (BiSCaO) water

The main component of scallop shells is calcium carbonate (CaCO3), which is converted to CaO when heated above 800 °C. Heated scallop shell powder is composed mainly of CaO and is called "bioshell calcium oxide (BiSCaO)", a material exhibiting broad antimicrobial activity against various pathogenic bacteria [1][2], avian influenza virus [3], heat-resistant bacterial spores [4], fungi [5], and biofilms [6][7]. In addition, BiSCaO is used as an additive to prolong the shelf life of food products [1]. BiSCaO itself is poorly water-soluble under strongly alkaline conditions (pH > 12.3). Consequently, water suspensions containing a high concentration of BiSCaO tends to plug spray nozzles due to precipitation [8].

In this study, we explored the possibility to test whether water containing highly concentrated BiSCaO can be made using commercially available BiSCaO (over 99.6% CaO is included), since a highly concentrated BiSCaO is thought be more potent against various infectious viruses and pathogenic bacteria. We added 10 wt% BiSCaO to pure water in a bottle and then collected the supernatant. The same volume of pure water was gently poured onto the BiSCaO precipitate accumulated in the bottle and the supernatant was carefully collected. This process was repeated fifty times. The resultant BiSCaO suspension contained smaller nanoparticles (100–200 nm in diameter), and was colorless and transparent with pH > 12.7. We call this "BiSCaO Water".

2. In Vitro Assay for the Disinfection Activity of BiSCaO Water against Pathogenic Bacterias and Viruses

Bactericidal activities of BiSCaO against Escherichia coli (E. coli) NBRC 3972, E. coli O-157:H7, P. aeruginosa, Salmonella, and Staphylococcus aureus (S. aureus) were evaluated by the Japan Food Research Laboratory (JFRL; Tokyo, Japan) (Table 1). The levels (colony forming units; CFU) of E. coli, P. aeruginosa, and Salmonella were reduced to below the detection limit within 5 min, 99% of E. coli O-157:H7 was eliminated after 5 min, and 97% of S. aureus (a Gram positive bacterium) was eliminated after 5 min and reduced to below the detection limit after 15 min.

Table 1. Assay of the activity of BiSCaO Water against pathogenic microbes in vitro.

Bacterial Strain

0 min

1 min

5 min

15 min

E. coli

3.6 × 105

< 10*

< 10*

E. coli  (control)

6.7 × 105

6.1 × 105

E. coli(O157:H7)

6.4 × 105

4.6 × 102

< 10*

E. coli(O157:H7) (control)

6.9 × 105

6.6 × 105

P. aeruginosa

1.4 × 104

< 10*

< 10*

P. aeruginosa  (control)

2.7 × 105

4.0 × 105


2.1 × 104

< 10*

< 10*

Salmonella  (control)

7.1 × 105

7.7 × 105

S. aureus

1.1 × 105

1.1 × 104

< 10*

S. aureus  (control)

3.4 × 105

4.7 × 105

< 10*: nondetected, ―: not determined. CFU: colony forming units

The virucidal activities of BiSCaO Water against influenza A (H1N1), an enveloped virus, and Feline calicivirus, a nonenveloped virus, were evaluated using the fifty-percent tissue culture infectious dose (TCID50) method [9][10], which was performed by JFRL (Table 2). Feline calicivirus treated with BiSCaO Water was reduced to below the detection limit within 1 min, and influenza A was reduced from 6.0 to 1.7 (TCID50/mL) at 1 min compared with the control, and then reduced to below the detection limit after 5 min.

Table 2. Assay of the activity of BiSCaO Water against an enveloped virus and a nonenveloped virus.

Virus Strain

0 min

1 min

5 min

15 min

Feline calicivirus


< 1.5*

< 1.5*

< 1.5*

Feline calicivirus (control)



Influenza A (H1N1)



< 1.5*

< 1.5*

Influenza A (H1N1) (control)



< 1.5*: nondetected, ―: not determined. TCID50: tissue culture infectious dose

3. Conclusions

BiSCaO Water contains nanoparticles and is colorless and transparent, with a pH > 12.7.  BiSCaO Water completely eliminated various pathogenic bacteria within 15 min and viruses within 5 min in in vitro assays. Furthermore, BiSCaO Water exhibited higher deodorization of tainted meat and higher microbicidal efficacy using suspensions contaminated with normal bacteria compared to ethanol, BiSCaO and BiSCa(OH)2 suspensions, povidone iodine, NaClO, BiSCaO dispersion and colloidal dispersion [11]. The present study showed that BiSCaO Water (pH > 12.7) has microbicidal activity against various pathogenic bacteria and viruses such as both enveloped virus and nonenveloped virus. Therefore, BiSCaO Water may be valuable for the limitation of the spread of respiratory viruses such as COVID-19, although it is necessary to study additional microbicidal/virubicidal activity including coronavirus SARS-CoV-2.



  1. Jun Sawai; Antimicrobial Characteristics of Heated Scallop Shell Powder and Its Application. Biocontrol Science 2011, 16, 95-102, 10.4265/bio.16.95.
  2. Takashi Watanabe; Riku Fujimoto; Jun Sawai; Mikio Kikuchi; Shinya Yahata; Susumu Satoh; Antibacterial Characteristics of Heated Scallop-Shell Nano-Particles. Biocontrol Science 2014, 19, 93-97, 10.4265/bio.19.93.
  3. Chanathip Thammakarn1) 2); Keisuke Satoh1); Atsushi Suguro1); Hakimullah Hakim; Sakchai Ruenphet3); Kazuaki Takehara; Inactivation of Avian Influenza Virus, Newcastle Disease Virus and Goose Parvovirus Using Solution of Nano-Sized Scallop Shell Powder. Journal of Veterinary Medical Science 2014, 76, 1277-1280, 10.1292/jvms.14-0158.
  4. Sawai Jun; Sporicidal kinetics of Baccillus subtilis spores by heated scallop shell powder. J. Food Prot. 2003, 66, 1482-1485.
  5. Ronge Xing; Yukun Qin; Xiaohong Guan; Song Liu; Huahua Yu; Pengcheng Li; Comparison of antifungal activities of scallop shell, oyster shell and their pyrolyzed products. The Egyptian Journal of Aquatic Research 2013, 39, 83-90, 10.1016/j.ejar.2013.07.003.
  6. Miki Kubo; Yori Ohshima; Fumio Irie; Mikio Kikuchi; Jun Sawai; Disinfection Treatment of Heated Scallop-Shell Powder on Biofilm of Escherichia coli ATCC 25922 Surrogated for E. coli O157:H7. Journal of Biomaterials and Nanobiotechnology 2013, 4, 10-19, 10.4236/jbnb.2013.44A002.
  7. Nobumitsu Shimamura; Fumio Irie; Takahiro Yamakawa; Mikio Kikuchi; Jun Sawai; Heated Scallop-Shell Powder Treatment for Deactivation and Removal of Listeria sp. Biofilm Formed at a Low Temperature. Biocontrol Science 2015, 20, 153-157, 10.4265/bio.20.153.
  8. Koichi Fukuda; Yoko Sato; Masayuki Ishihara; Shingo Nakamura; Tomohiro Takayama; Kaoru Murakami; Masanori Fujita; Hidetaka Yokoe; Skin Cleansing Technique with Disinfectant using Improved High-Velocity Steam-Air Micromist Jet Spray. Biocontrol Science 2020, 25, 35-39, 10.4265/bio.25.35.
  9. Vinh Quang Nguyen; Masayuki Ishihara; Jun Kinoda; Hidemi Hattori; Shingo Nakamura; Takeshi Ono; Yasushi Miyahira; Takemi Matsui; Development of antimicrobial biomaterials produced from chitin-nanofiber sheet/silver nanoparticle composites.. Journal of Nanobiotechnology 2014, 12, 49, 10.1186/s12951-014-0049-1.
  10. G. Kampf; Daniel Todt; Stephanie Pfaender; Eike Steinmann; Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. Journal of Hospital Infection 2020, 104, 246-251, 10.1016/j.jhin.2020.01.022.
  11. Shingo Nakamura; Masayuki Ishihara; Yoko Sato; Tomohiro Takayama; Sumiyo Hiruma; Naoko Ando; Koichi Fukuda; Kaoru Murakami; Hidetaka Yokoe; Concentrated Bioshell Calcium Oxide (BiSCaO) Water Kills Pathogenic Microbes: Characterization and Activity. Molecules 2020, 25, 3001, 10.3390/molecules25133001.
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