Acinetobacter rudis sp. nov., isolated from raw milk and raw wastewater.

Two bacterial strains, G30(T) and A1PC16, isolated respectively from raw milk and raw wastewater, were characterized using a polyphasic approach. Chemotaxonomic characterization supported the inclusion of these strains in the genus Acinetobacter, with Q-8 and Q-9 as the major respiratory quinones, genomic DNA G+C contents within the range observed for this genus (38-47 mol%) and C(16:0), C(18:1)ω9c and C(16:1)ω7c/iso-C(15:0) 2-OH as the predominant fatty acids. The observation of 16S rRNA gene sequence similarity lower than 97% with other Acinetobacter species with validly published names led to the hypothesis that these isolates could represent a novel species. This hypothesis was supported by comparative analysis of partial sequences of the genes rpoB and gyrB, which showed that strains G30(T) and A1PC16 did not cluster with any species with validly published names, forming a distinct lineage. DNA-DNA hybridizations confirmed that the two strains were members of the same species, which could be distinguished from their congeners by several phenotypic characteristics. On the basis of these arguments, it is proposed that strains G30(T) and A1PC16 represent a novel species, for which the name Acinetobacter rudis sp. nov. is proposed. The type strain is strain G30(T) (=LMG 26107(T) =CCUG 57889(T) =DSM 24031(T) =CECT 7818(T)).

Epilithonimonas lactis sp. nov., isolated from raw cow's milk.

A Gram-staining-negative, rod-shaped, oxidase-positive, aerobic, non-motile and yellow-pigmented bacterial strain containing flexirubin type pigments, designated H1(T), was isolated from raw cow's milk in Israel. 16S rRNA gene sequence analysis indicated that the isolate should be placed in the genus Epilithonimonas (family Flavobacteriaceae, phylum Bacteroidetes). The level of 16S rRNA gene sequence similarity between strain H1(T) and the type strain of Epilithonimonas tenax was 97.6 %. Strain H1(T) grew at 5-33 degrees C and with 0-2.0 % NaCl. The dominant cellular fatty acids of strain H1(T) were iso-C(15 : 0), iso-C(17 : 0) 3-OH and summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1) omega7c), and the DNA G+C content was 38.0 mol%. On the basis of phenotypic properties and phylogenetic distinctiveness, the milk isolate is classified as a new species in the genus Epilithonimonas , for which the name Epilithonimonas lactis sp. nov. (type strain H1(T) =LMG 24401(T) =DSM 19921(T)) is proposed.

Chryseobacterium bovis sp. nov., isolated from raw cow's milk.

Three Gram-negative, rod-shaped, oxidase-positive, aerobic, non-motile bacterial strains, designated H9T, H10 and H15, were isolated during a study on the diversity of culturable psychrotolerant bacteria in raw cow's milk. Comparisons of 16S rRNA gene sequences showed that the three strains were very closely related to each other (sequence similarities of 99.6-99.8 %). A polyphasic taxonomic study of the isolates resulted in their identification as members of the genus Chryseobacterium (family Flavobacteriaceae, phylum Bacteroidetes). The three strains showed < or =96.9 % sequence similarity with respect to the type strains of described Chryseobacterium species, indicating that H9T, H10 and H15 represent a novel species of the genus Chryseobacterium. The three strains grew at 7-37 degrees C (strain H10 grew at up to 41 degrees C), with 0-2.5 % NaCl and at pH 5.0-9.8. The dominant cellular fatty acids of strain H9T were 15 : 0 iso (38.9 %), 15 : 0 anteiso (15.6 %) and 17 : 0 iso 3-OH (12.7 %). Strain H10 also possessed 17 : 1 iso omega 9c (14.8 %) as a major fatty acid. On the basis of phenotypic properties and phylogenetic distinctiveness, the three milk isolates represent a novel species in the genus Chryseobacterium, for which the name Chryseobacterium bovis sp. nov. is proposed. The type strain is H9T (=LMG 24227T =DSM 19482T).

Chryseobacterium oranimense sp. nov., a psychrotolerant, proteolytic and lipolytic bacterium isolated from raw cow's milk.

A Gram-negative, rod-shaped, oxidase-positive, aerobic, non-motile and orange-pigmented bacterial strain, containing flexirubin-type pigments, designated H8(T), was isolated from raw cow's milk in Israel. 16S rRNA gene sequence analysis indicated that the isolate should be placed in the genus Chryseobacterium (family Flavobacteriaceae, phylum Bacteroidetes). The levels of 16S rRNA gene sequence similarity between strain H8(T) and the type strains of described Chryseobacterium species were 97.5 % or lower. Strain H8(T) grew at 5-37 degrees C and with 0-3.0 % NaCl. The dominant cellular fatty acids were iso-15 : 0, iso-17 : 0 3-OH, iso-17 : 1omega9c and summed feature 3 (comprising iso-15 : 0 2-OH and/or 16 : 1omega7c). On the basis of phenotypic properties and phylogenetic distinctiveness, the milk isolate H8(T) is classified as a member of a novel species in the genus Chryseobacterium, for which the name Chryseobacterium oranimense sp. nov. (type strain H8(T) =LMG 24030(T) =DSM 19055(T)) is proposed.

Chryseobacterium haifense sp. nov., a psychrotolerant bacterium isolated from raw milk.

Strain H38(T) was isolated during a study on the diversity of culturable psychrotolerant bacteria in raw milk. Comparative 16S rRNA gene sequence analysis showed that strain H38(T) belongs to the genus Chryseobacterium (family Flavobacteriaceae, phylum Bacteroidetes), with the highest similarity (96.7 %) to Chryseobacterium hispanicum VP48(T). Strain H38(T) grows aerobically, at 4-41 degrees C, with 0-2.5 % NaCl and at pH 6.5-10.5. Light induces the formation of yellow carotenoid pigments. The dominant cellular fatty acids are 15 : 0 iso (41.6 %), 15 : 0 anteiso (16.6 %) and 17 : 0 iso 3-OH (10.3 %). The G+C content of the DNA is 37.8 mol%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain H38(T) (=LMG 24029(T) =DSM 19056(T)) is classified in the genus Chryseobacterium as the type strain of a novel species, for which the name Chryseobacterium haifense sp. nov. is proposed.

Culturable psychrotrophic bacterial communities in raw milk and their proteolytic and lipolytic traits.

During cold storage after milk collection, psychrotrophic bacterial populations dominate the microflora, and their extracellular enzymes, mainly proteases and lipases, contribute to the spoilage of dairy products. The diversity, dynamics, and enzymatic traits of culturable psychrotrophs in raw milk from four farms were investigated over a 10-month period. About 20% of the isolates were found to be novel species, indicating that there is still much to be learned about culturable psychrotrophs in raw milk. The psychrotrophic isolates were identified and classified in seven classes. Three classes were predominant, with high species richness (18 to 21 species per class) in different seasons of the year: Gammaproteobacteria in spring and winter, Bacilli in summer, and Actinobacteria in autumn. The four minor classes were Alphaproteobacteria, Betaproteobacteria, Flavobacteria, and Sphingobacteria. The dominant classes were found in all four dairies, although every dairy had its own unique "bacterial profile." Most but not all bacterial isolates had either lipolytic or both lipolytic and proteolytic activities. Only a few isolates showed proteolytic activity alone. The dominant genera, Pseudomonas and Acinetobacter (Gammaproteobacteria), showed mainly lipolytic activity, Microbacterium (Actinobacteria) was highly lipolytic and proteolytic, and the lactic acid bacteria (Lactococcus and Leuconostoc) displayed very minor enzymatic ability. Hence, the composition of psychrotrophic bacterial flora in raw milk has an important role in the determination of milk quality. Monitoring the dominant psychrotrophic species responsible for the production of heat-stable proteolytic and lipolytic enzymes offers a sensitive and efficient tool for maintaining better milk quality in the milk industry.