[Taxonomical status of the psychrotolerant Antarctic microorganisms].

The aerobic chemoorganotrophic bacteria, dominating in soils and phytocenosis of the Antarctic Region, on combination of morphological and biochemical properties belong to several taxons of Bacteria domain. Gram-negative strains 3189, 3415 (fam. Halomonadaceae, Halomonas sp.) and 3088, 3468, 3469 (fam. Moraxellaceae, Psychrobacter sp.) belong to phylum Proteobacteria, to class Gammaproteobacteria. Gram-negative strains 3294 3392 (Rhizobiales, fam. Methylobacteriaceae, Methylobacterium sp.) relate to class Alphaproteobacteria of this phylum. Gram-positive strains 3179, 3275, 3470, 3471 (fam. Microbacteriaceae, Cryobacterium sp.), 3054, 3058, 3411 (fam. Corynebacteriaceae, Corynebacterium sp.) and 3194, 3398 (fam. Micrococcaceae, Micrococcus sp.) relate to phylum Actinobacteria, class Actinobacteria. Thus, the psychrophilic and psychrotolerant Antarctic bacteria (aerobic chemoorganotrophic) isolated from phytocenosis and soils of polar region are characterized by wide taxonomic variety.

Genus Enhydrobacter Staley et al. 1987 should be recognized as a member of the family Rhodospirillaceae within the class Alphaproteobacteria.

The genus Enhydrobacter, first reported as a member of the family Vibrionaceae, has been placed in the family Moraxellaceae, but as a genus incertae sedis in Bergey's Manual of Systematic Bacteriology 2nd edition. During our taxonomic investigation of Enhydrobacter-like organisms, we observed that the 16S rRNA sequences of E. aerosaccus-type strain versions NCIMB 12535(T) , ATCC 27094( T) and CCUG 58314(T) were very different from the accessible data (accession no. AJ550856). Phylogenetic analysis of our 16S rRNA sequence data revealed that these organisms were located within the family Rhodospirillaceae. The genera Inquilinus, Oceanibaculum, Skermanella and Nisaea were closely related (sequence similarities were 88.3~87.0%), but Enhydrobacter could be distinguished from these genera by growth characteristics, fatty acid profiles (C(19:0) cyclo ω8c; 38.4% C(18:1) ω7c; 32.2%, and C(16:0) ; 8.9% were major components), in being non-flagellated, and differing in enzymatic activities, including trypsin and ß-glucosidase. From these data, we conclude that the genus Enhydrobacter should be recognized as an independent genus of the family Rhodospirillaceae within the class Alphaproteobacteria.

Changes in psychrotrophic microbial populations during milk creaming to produce Grana Trentino cheese.

The aim of this study was to study the psychrotrophic microbiota developing during milk creaming of Grana Trentino cheese-making. 138 isolates from raw whole milk, cream and skim milk samples were screened by Randomly amplified polymorphic DNA PCR biotyping and representative strains of each biotype were characterised by partial 16S rRNA gene sequencing and enzymatic activity. Pseudomonadaceae were commonly isolated in cream samples while Streptococcaceae and Enterobacteriaceae in milk samples. Moraxellaceae and Flavobacteriaceae were found in both cream and milk samples. More than 80% of psychrotrophic isolates could grow at 37°C. All Flavobacteriaceae and half of Pseudomonadaceae biotypes displayed proteolytic activity on milk agar even at low temperatures such as 10°C. All Streptococcaceae and some of Enterobacteriaceae displayed acidifying activity and almost all Acinetobacter spp. (Moraxellaceae) displayed lipolytic activity towards tributyrin. Even if psychrotrophic bacteria is not the dominant microbial group in raw milk, their total number increases during creaming and becomes one of the most present group together with Lactic Acid Bacteria. Their enzymatic activities may be key players in determining milk quality for cheese making.

A new labyrinthulid isolate that produces only docosahexaenoic acid.

We show here that a new labyrinthulid strain, L72, isolated from a fallen leaf in the Seto Inland Sea of Japan, produced only docohexaenoic acid (DHA) among all the long-chain polyunsaturated fatty acids (LCPUFAs). The main fatty acid composition was 16:0 (28.9%), 18:0 (7.2%), 18:1 (5.7%), 18:2 (10.4%), and DHA (45.9%) without any other LCPUFA. The lipid content of the strain was 27.4%. The cells had many lipid bodies, which were densely located in all of the cells. On phylogenetic analysis using the 18S rDNA sequence, the strain was located in the labyrinthulids group, forming a monophyletic group with Labyrinthula sp. (strain s) and Labyrinthuila sp. (strain L59). We further tested the culture optimization of strain L72 to evaluate the ability of the strain to produce DHA. The optimum salt concentration and the temperature of the strain were 100% of artificial seawater and 20 degrees C. Strain L72 could grow well on soybean oil (SBO) or soybean lecithin (SBL) as the carbon source. When 20 g/l of SBL was added to the medium, DHA production reached the maximum amount at 0.67 g/l for 14 d. The two important facts, that the strain can use SBL as the main nutrient and contains only DHA among the LCPUFAs, will be of great advantage for industry.