Table 4.

Characteristics of the dominant bacterial genera detected on basil leaves [47].

Genus	Gram Staining	Respiratory Metabolism	Motility	Temperature Range Growth	Habitat	Pathogenicity
Flavobacterium	Gram negative	Aerobic	Nonmotile or motile by gliding	−7 to 45 °C	Soil, freshwater, marine and saline environments	Some species, such as F. columnare, F. psychrophilum and F. branchiophilum, are pathogenic for freshwater fish. Some strains of F. johnsoniae are plant pathogens causing soft rot in various plants.
Sphingobacterium	Gram negative	Aerobic	Sliding motility	2 to 45 °C	Soil and composted manure	Some species are opportunistic pathogens for humans.
Acinetobacter	Gram negative	Aerobic	Twitching motility by fimbriae	20 to 37 °C	Soil, water, sewage and plants	Although considered normally nonpathogenic, they may cause nosocomial infections such as bacteremia, secondary meningitis, pneumonia, and urinary tract infections in humans.
Pseudomonas	Gram negative	Aerobic	Motile by one or several polar flagella and fimbriae	4 to 45 °C	Plants (rhizospheres and leave surfaces) and soil	Some species are pathogenic for humans, animals, or plants. Plant pathogenic species such as P. syringae may cause tumorous outgrowth, rot, blight or chlorosis, and necrosis in plants due to secretion of substances (such as toxins, plant hormones and enzymes) which alter the normal metabolism of plant cells. Others are opportunistic pathogens for animals and humans, such as P. aeruginosa.
Citrobacter	Gram negative	Facultatively anaerobic	Usually motile by peritrichous flagella	5 to >37 °C	Intestinal tract of humans and some animals, soil, water, sewage, plants and food (vegetables, dairy, fish)	Some species are opportunistic pathogens for humans.
Enterobacter	Gram negative	Facultatively anaerobic	Motile by peritrichous flagella	4 to 44 °C	Plants (rhizophere and leaves) and the intestinal tract of humans and animals	Some species are plant pathogens, such as E. nimipressuralis (wetwood in elm trees), E. cancerogenus (canker disease of Populus species) and E. pyrinus (brown leaf spot disease in pears).
Erwinia	Gram negative	Facultatively anaerobic	Motile by peritrichous flagella	0 to 40 °C	Plants	Plant pathogens which cause mainly blights and wilts. Infection through natural openings and wounds, followed by spread through the vascular tissue.
Klebsiella	Gram negative	Facultatively anaerobic	Nonmotile (except K. mobilis)	5 to 45 °C	Intestinal tract of humans and animals, soil, water, sewage and plants	Opportunistic and nosocomial human pathogens, e.g. K. pneumoniae, causing pneumonia, urinary tract infections, bacteremia and sepsis.
Kluyvera	Gram negative	Facultatively anaerobic	Motile	4 to 40 °C	Intestinal tract of humans and animals, soil, sewage and food (milk, dairy and other food products of animal origin)	Opportunistic human pathogen.
Pantoea	Gram negative	Facultatively anaerobic	Most strains are motile by peritrichous flagella	4 to 41 °C	Plants, seeds, fruits, soil and water	Some strains are opportunistic pathogens for plants, humans and animals.
Rahnella	Gram negative	Facultatively anaerobic	Motile by peritrichous flagella	1 to ≥37 °C	Fresh water, soil, plant rhizosphere, intestinal tract of snails	Opportunistic human pathogens causing wound infections, bacteremias, acute gastroenteritis and septicemia.