Underrecognized niche of spore-forming bacilli as a nitrite-producer isolated from the processing lines and end-products of powdered infant formula

Tae Jin Cho, Min-Suk Rhee

Research output: Contribution to journalArticle

Abstract

Although nitrite in powdered milk formula (PIF) is a recognized health risk for infants, the presence of nitrite in PIF has only been investigated as a chemical contaminant during the inspection of end-products. The risk posed by microbial sources of nitrite during the PIF manufacturing process has not been considered. This is the first study to report the taxonomy and physiological characteristics of nitrite-producing bacteria isolated from PIF processing environments. All isolates identified as nitrite-producers (133 out of 501 strains collected over four years) from work-in-process and end-products of PIF were spore-forming bacilli. Nitrite-producing metabolism under PIF processing conditions was found in not only thermophilic isolates (3 Bacillus, 60 Geobacillus from 63 strains; 100%) but also in mesophilic isolates (65 Bacillus, 1 Anoxybacillus from 70 strains; 65.7%). Geobacillus was the only highly heat-resistant sporeformer and vigorous nitrite-producer exhibiting dramatic increases in nitrite over short periods of incubation (a maximum value within 3 h). High conversions of nitrate to nitrite (up to 88.8%) was also observed, highlighting bacteria as a key source of nitrite in PIF processing lines. Further research into the diversity of metabolic activity observed in this study can facilitate specialized management of nitrite-producers in PIF processing lines.

Original languageEnglish
Pages (from-to)50-61
Number of pages12
JournalFood Microbiology
Volume80
DOIs
Publication statusPublished - 2019 Jun 1

Fingerprint

Infant Formula
infant formulas
Nitrites
Spores
nitrites
Bacillus
dried milk
niches
spores
Milk
Geobacillus
Bacillus (bacteria)
Anoxybacillus
Bacilli
Bacteria
bacteria
Nitrates
manufacturing
Hot Temperature
nitrates

Keywords

  • Geobacillus
  • Nitrite
  • Powdered infant formula
  • Spore-forming bacilli

ASJC Scopus subject areas

  • Food Science
  • Microbiology

Cite this

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abstract = "Although nitrite in powdered milk formula (PIF) is a recognized health risk for infants, the presence of nitrite in PIF has only been investigated as a chemical contaminant during the inspection of end-products. The risk posed by microbial sources of nitrite during the PIF manufacturing process has not been considered. This is the first study to report the taxonomy and physiological characteristics of nitrite-producing bacteria isolated from PIF processing environments. All isolates identified as nitrite-producers (133 out of 501 strains collected over four years) from work-in-process and end-products of PIF were spore-forming bacilli. Nitrite-producing metabolism under PIF processing conditions was found in not only thermophilic isolates (3 Bacillus, 60 Geobacillus from 63 strains; 100{\%}) but also in mesophilic isolates (65 Bacillus, 1 Anoxybacillus from 70 strains; 65.7{\%}). Geobacillus was the only highly heat-resistant sporeformer and vigorous nitrite-producer exhibiting dramatic increases in nitrite over short periods of incubation (a maximum value within 3 h). High conversions of nitrate to nitrite (up to 88.8{\%}) was also observed, highlighting bacteria as a key source of nitrite in PIF processing lines. Further research into the diversity of metabolic activity observed in this study can facilitate specialized management of nitrite-producers in PIF processing lines.",
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