Numerically dominant denitrifying bacteria from world soils

Area of Science:

• Microbiology
• Environmental Science
• Bacteriology

Background:

• Denitrification is a crucial microbial process in nitrogen cycling.
• Understanding denitrifier populations is vital for environmental management and biogeochemical studies.

Purpose of the Study:

• To identify dominant denitrifier populations in various global environments.
• To characterize isolates and compare them with known denitrifier species.
• To assess the diversity and prevalence of denitrification in different sample types.

Main Methods:

• Isolation of anaerobic nitrate-reducing organisms from diverse soils, sediments, and manure.
• Purification and verification of 146 denitrifying isolates.
• Characterization using 52 properties and numerical taxonomy for comparison with nine known species.

Main Results:

• Pseudomonas fluorescens biotype II and Alcaligenes were the most prevalent denitrifiers.
• Flavobacterium species, previously unknown to denitrify, were identified.
• Dominant isolates did not resemble commonly studied species like Pseudomonas denitrificans or Paracoccus denitrificans.
• High diversity of denitrifiers was observed in most samples.
• Isolate growth temperature correlated significantly with environmental temperature.

Conclusions:

• Denitrification is a common trait in a diverse range of gram-negative, motile bacteria.
• The dominant denitrifiers are not necessarily the most studied species.
• Environmental temperature is a key factor influencing denitrifier populations.