Mycetocola spongiae sp. nov., isolated from deep-sea sponge Cacospongia mycofijiensis

A novel bacterial strain (MSC19^T) was isolated from a deep-sea sponge Cacospongia mycofijiensis collected in the Mariana Trench at a depth of 2681 m. The cells of the new isolate were Gram-stain-positive, non-motile, oxidase- and catalase-positive, rod-shaped and yellow-coloured. They could grow at 4-32 °C (optimum, 28 °C), pH 5.5-12 (optimum, pH 7.0) and with 0-12 % (w/v) NaCl (optimum, 4 %). The strain's 16S rRNA gene sequence showed 98.41 % similarity to that of Mycetocola saprophilus CM-01^T. Phylogenetic analysis further suggested that strain MSC19^T represents a new species within the genus Mycetocola. The total genome of MSC19^T was approximately 3 196 754 bp in size with a G+C content of 66.43 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among MSC19^T and other Mycetocola type strains were 70.35-75.37 % (ANIb), 83.79-84.73 % (ANIm) and 20.3-21.7 % (dDDH). The major fatty acids of MSC19^T were composed of anteiso-C_15 : 0, iso-C_16 : 0 and anteiso-C_17 : 0, and its predominant menaquinones were MK-10 and MK-9. The polar lipids of MSC19^T mainly consisted of diphosphatidylglycerol, phosphatidylglycerol and glycolipid. The diagnostic cell-wall diamino acid was lysine. Combined molecular, physiological, biochemical and chemotaxonomic analyses suggest that strain MSC19^T represents a novel species of the genus Mycetocola, for which the name Mycetocola spongiae sp. nov. is proposed. The type strain is MSC19^T (=MCCC 1K06265^T=KCTC 49701^T).

Bacterial Brown Pit, a New Disease of Edible Mushrooms Caused by Mycetocola sp

From September to December 2018, commercial button mushroom (Agaricus bisporus) farms in central Iran were surveyed to monitor the causal agent(s) of browning and blotch symptoms on mushroom caps. In addition to dozens of pseudomonads (i.e., Pseudomonas tolaasii and Pseudomonas reactans), six slow-growing gram-positive bacterial strains were isolated from blotched mushroom caps. These bacteria presented as creamy white, circular, smooth, nonfluorescent, and shiny colonies with whole margins resembling members of Microbacteriaceae (Actinobacteria). All of the actinobacterial strains were aggressively pathogenic on cut cap surface of two edible mushrooms (i.e., A. bisporus and Pleurotus eryngii), inducing brown pit symptoms 48 h postinoculation. The strains did not induce symptoms on the vegetables tested (i.e., carrot, cucumber, and potato), and they did not affect the growth of mycelium of tested plant-pathogenic fungi (i.e., Acremonium sp., Fusarium spp., and Phytopythium sp.). Phylogeny of 16S ribosomal RNA and multilocus sequence analysis of six housekeeping genes (i.e., atpD, dnaK, gyrB, ppK, recA, and rpoB) revealed that the bacterial strains belong to the actinobacterial genus Mycetocola spp., whereas the species status of the strains remains undetermined. Mushroom-associated Mycetocola species were previously reported to be capable of detoxifying tolaasin, a toxin produced by P. tolaasii, whereas the strains isolated in this study did not show tolaasin detoxification activities. Altogether, this is the first report of a mushroom disease caused by an actinobacterial species, and "bacterial brown pit" was assigned as the common name of the disease.

Mycetocola zhujimingii sp. nov., isolated from faeces of Tibetan antelopes (Pantholops hodgsonii)

Strains 449^T and 622 are both aerobic, Gram-stain-positive, short, rod-shaped bacilli that were recently isolated from the faeces of Tibetan antelopes on the Qinghai-Tibet Plateau in China. Their 16S rRNA gene sequences were most similar to those of Mycetocola zhadangensis ZD1-4^T(97.9-98.0 %) and Mycetocola miduiensis CGMCC 1.11101^T(97.3-97.4 %). Phylogenetic analysis of the 16S rRNA gene sequences further suggested that strains 449^T and 622 represent a new lineage within the genus Mycetocola. The G+C content of strain 449^T is 64.9 mol%. Optimal growth was achieved at pH 7.0 and 28 °C. Cells contained anteiso-C15 : 0 as the major cellular fatty acid, MK-10 and MK-11 as predominant menaquinones, diphosphatidylglycerol and phosphatidylglycerol as major polar lipids, and lysine as the diagnostic diamino acid. The DNA-DNA hybridization values of strains 449^T and 622 were below the 70 % cut-off with respect to known strains of the genus Mycetocola. Based on these genotypic, phenotypic and biochemical characteristics, it seems rational to conclude that strains 449^T and 622 belong to the genus Mycetocola and thus represent a novel species, for which the name Mycetocola zhujimingii sp. nov. is proposed. The type strain is 449^T (=CGMCC 1.16372^T=DSM 106173^T).

Luethyella okanaganae gen. nov., sp. nov., a Novel Genus and Species of the Family Microbacteriaceae Isolated from the Insect Okanagana rimosa

The entomopathogen "Corynebacterium okanaganae" was described by Lüthy in 1974 but the name was never validly published. Phylogenetic analysis employing 16S rRNA gene sequences demonstrate that "Corynebacterium okanaganae" is not a member of the genus Corynebacterium but related to members of the Microbacteriaceae being most closely related to, but distinct from, members of the genera Rathayibacter, Mycetocola and Curtobacterium. The bacterium is an aerobic, Gram-positive staining, rod-shaped actinobacterium with the cell-wall peptidoglycan based on 2,4, diaminobutyric acid as the diagnostic diamino acid. The predominant menaquinones are MK-10, MK-11 and MK-12, and the principle polar lipids are phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids consist of anteiso-C_15:0 and anteiso-C_17:0. Therefore, based upon the phylogenetic, biochemical, and chemotaxonomic information, the organism merits recognition as a novel species and genus in the family Microbacteriaceae, for which the name Luethyella okanaganae gen. nov. sp. nov. is proposed. The type strain is LBG B4405^T = CCUG 43304^T = NCIMB 702272^T.

Biodiversity of the Surface Microbial Consortia from Limburger, Reblochon, Livarot, Tilsit, and Gubbeen Cheeses

Comprehensive collaborative studies from our laboratories reveal the extensive biodiversity of the microflora of the surfaces of smear-ripened cheeses. Two thousand five hundred ninety-seven strains of bacteria and 2,446 strains of yeasts from the surface of the smear-ripened cheeses Limburger, Reblochon, Livarot, Tilsit, and Gubbeen, isolated at three or four times during ripening, were identified; 55 species of bacteria and 30 species of yeast were found. The microfloras of the five cheeses showed many similarities but also many differences and interbatch variation. Very few of the commercial smear microorganisms, deliberately inoculated onto the cheese surface, were reisolated and then mainly from the initial stages of ripening, implying that smear cheese production units must have an adventitious "house" flora. Limburger cheese had the simplest microflora, containing two yeasts, Debaryomyces hansenii and Geotrichum candidum, and two bacteria, Arthrobacter arilaitensis and Brevibacterium aurantiacum. The microflora of Livarot was the most complicated, comprising 10 yeasts and 38 bacteria, including many gram-negative organisms. Reblochon also had a very diverse microflora containing 8 yeasts and 13 bacteria (excluding gram-negative organisms which were not identified), while Gubbeen had 7 yeasts and 18 bacteria and Tilsit had 5 yeasts and 9 bacteria. D. hansenii was by far the dominant yeast, followed in order by G. candidum, Candida catenulata, and Kluyveromyces lactis. B. aurantiacum was the dominant bacterium and was found in every batch of the 5 cheeses. The next most common bacteria, in order, were Staphylococcus saprophyticus, A. arilaitensis, Corynebacterium casei, Corynebacterium variabile, and Microbacterium gubbeenense. S. saprophyticus was mainly found in Gubbeen, and A. arilaitensis was found in all cheeses but not in every batch. C. casei was found in most batches of Reblochon, Livarot, Tilsit, and Gubbeen. C. variabile was found in all batches of Gubbeen and Reblochon but in only one batch of Tilsit and in no batch of Limburger or Livarot. Other bacteria were isolated in low numbers from each of the cheeses, suggesting that each of the 5 cheeses has a unique microflora. In Gubbeen cheese, several different strains of the dominant bacteria were present, as determined by pulsed-field gel electrophoresis, and many of the less common bacteria were present as single clones. The culture-independent method, denaturing gradient gel electrophoresis, resulted in identification of several bacteria which were not found by the culture-dependent (isolation and rep-PCR identification) method. It was thus a useful complementary technique to identify other bacteria in the cheeses. The gross composition, the rate of increase in pH, and the indices of proteolysis were different in most of the cheeses.

Traditional cheeses: rich and diverse microbiota with associated benefits

The risks and benefits of traditional cheeses, mainly raw milk cheeses, are rarely set out objectively, whence the recurrent confused debate over their pros and cons. This review starts by emphasizing the particularities of the microbiota in traditional cheeses. It then describes the sensory, hygiene, and possible health benefits associated with traditional cheeses. The microbial diversity underlying the benefits of raw milk cheese depends on both the milk microbiota and on traditional practices, including inoculation practices. Traditional know-how from farming to cheese processing helps to maintain both the richness of the microbiota in individual cheeses and the diversity between cheeses throughout processing. All in all more than 400 species of lactic acid bacteria, Gram and catalase-positive bacteria, Gram-negative bacteria, yeasts and moulds have been detected in raw milk. This biodiversity decreases in cheese cores, where a small number of lactic acid bacteria species are numerically dominant, but persists on the cheese surfaces, which harbour numerous species of bacteria, yeasts and moulds. Diversity between cheeses is due particularly to wide variations in the dynamics of the same species in different cheeses. Flavour is more intense and rich in raw milk cheeses than in processed ones. This is mainly because an abundant native microbiota can express in raw milk cheeses, which is not the case in cheeses made from pasteurized or microfiltered milk. Compared to commercial strains, indigenous lactic acid bacteria isolated from milk/cheese, and surface bacteria and yeasts isolated from traditional brines, were associated with more complex volatile profiles and higher scores for some sensorial attributes. The ability of traditional cheeses to combat pathogens is related more to native antipathogenic strains or microbial consortia than to natural non-microbial inhibitor(s) from milk. Quite different native microbiota can protect against Listeria monocytogenes in cheeses (in both core and surface) and on the wooden surfaces of traditional equipment. The inhibition seems to be associated with their qualitative and quantitative composition rather than with their degree of diversity. The inhibitory mechanisms are not well elucidated. Both cross-sectional and cohort studies have evidenced a strong association of raw-milk consumption with protection against allergic/atopic diseases; further studies are needed to determine whether such association extends to traditional raw-milk cheese consumption. In the future, the use of meta-omics methods should help to decipher how traditional cheese ecosystems form and function, opening the way to new methods of risk-benefit management from farm to ripened cheese.

Mycetocola zhadangensis sp. nov., isolated from snow

A Gram-stain-positive, aerobic, short rod-shaped bacterium, strain ZD1-4T, was isolated from the Zhadang Glacier snow pit. The 16S rRNA gene sequence of the isolate showed highest similarity (98.8 %) to that of Mycetocola manganoxydans MB1-14T. The major fatty acids of strain ZD1-4T were anteiso-C15 : 0, C16 : 0, C18 : 0 and anteiso-C17 : 0. It possessed diphosphatidylglycerol as one of the major polar lipids, and MK-10 and MK-11 as the predominant isoprenoid quinones. The DNA G+C content of strain ZD1-4T was 63.8±0.2 mol% (T m). A number of phenotypic characteristics distinguished this bacterium from the type strains of other species of the genus Mycetocola . Moreover, the novel isolate showed only approximately 50 % DNA–DNA relatedness with M. manganoxydans MB1-14T. According to these genotypic and phenotypic data, it is evident that strain ZD1-4T represents a novel species of the genus Mycetocola , for which the name Mycetocola zhadangensis sp. nov. is proposed. The type strain is ZD1-4T ( = KACC 16570T = CGMCC 1.12042T).

Mycetocola miduiensis sp. nov., a psychrotolerant bacterium isolated from Midui glacier

An aerobic, asporous, flagellated, Gram-stain-positive, rod-shaped bacterium MD-T1-10-2T was isolated from the topsoil of Midui Glacier, Tibet Province, China. Phylogenetic analysis based on 16S rRNA gene sequence analysis placed the strain in a clade containing Mycetocola manganoxydans CCTCC AB 209002T, Mycetocola reblochoni DSM 18580T, Mycetocola tolaasinivorans JCM 11656T, Mycetocola lacteus JCM 11654T and Mycetocola saprophilus JCM 11655T, with the sequence similarities of 99.2, 98.1, 96.7, 96.6 and 96.4 %, respectively. DNA–DNA hybridization analysis indicated that strain MD-T1-10-2T represented a new member of this genus. The optimal ranges of temperature and pH for growth were 20–25 °C and 7.0–9.0, respectively; the strain could even grow at 0 °C. The major cellular fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The predominant menaquinones were MK-10 and MK-11. The cell wall amino acids were lysine, alanine, glycine and glutamic acids. The DNA G+C content was 65.9 mol%. Based on the genotypic and phenotypic data, strain MD-T1-10-2T for which the name Mycetocola miduiensis sp. nov. is proposed; the type strain is MD-T1-10-2T ( = CGMCC 1.11101T = NBRC 107877T).

Mycetocola manganoxydans sp. nov., an actinobacterium isolated from the Taklamakan desert

Two Gram-staining-positive, aerobic, non-sporulating bacteria forming short rods and cocci, designated MB1-7 and MB1-14T, were isolated from the Taklamakan desert. The isolates could oxidize manganese (II) ions. The isolates shared 95.4–98.0 % 16S rRNA gene sequence similarity with members of the genus Mycetocola . Although the isolates possessed chemotaxonomic properties similar to those of Mycetocola reblochoni , they were readily distinguished from this taxon by DNA–DNA relatedness and phenotypic characters. According to morphological and chemotaxonomic characteristics, as well as phylogenetic analysis and DNA–DNA relatedness, the two isolates represent a novel species of the genus Mycetocola , for which the name Mycetocola manganoxydans sp. nov. is proposed. The type strain is MB1-14T ( = CCTCC AB 209002T  = KCTC 19753T).

Compostimonas suwonensis gen. nov., sp. nov., isolated from spent mushroom compost

A Gram-positive, aerobic, non-motile, short rod, designated SMC46T, was isolated from a spent mushroom compost sample collected in the Suwon region, South Korea. 16S rRNA gene sequence analysis revealed that strain SMC46T was a member of the family Microbacteriaceae ; however, the isolate formed a branch separate from other genera within the family. Sequence similarity between strain SMC46T and other members of the family Microbacteriaceae was ≤97 %, the highest sequence similarity being with Frigoribacterium faeni 801T and Frondihabitans australicus E1HC-02T (both 97.0 %). Some chemotaxonomic properties of strain SMC46T were consistent with those of the family Microbacteriaceae : MK-11 and MK-12 as the predominant menaquinones, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 as the major cellular fatty acids and diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid as the polar lipids. However, strain SMC46T contained a B-type peptidoglycan not previously found in the family Microbacteriaceae . The DNA G+C content was 68 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic distinctiveness, strain SMC46T was considered to represent a novel genus and species in the family Microbacteriaceae , for which the name Compostimonas suwonensis gen. nov., sp. nov. is proposed. The type strain of the type species is SMC46T ( = KACC 13354T  = NBRC 106304T).

Surface microbial consortia from Livarot, a French smear-ripened cheese

The surface microflora (902 isolates) of Livarot cheeses from three dairies was investigated during ripening. Yeasts were mainly identified by Fourier transform infrared spectroscopy. Geotrichum candidum was the dominating yeast among 10 species. Bacteria were identified using Biotype 100 strips, dereplicated by repetitive extragenic palindromic PCR (rep-PCR); 156 representative strains were identified by either BOX-PCR or (GTG)(5)-PCR, and when appropriate by 16S rDNA sequencing and SDS-PAGE analysis. Gram-positive bacteria accounted for 65% of the isolates and were mainly assigned to the genera Arthrobacter , Brevibacterium , Corynebacterium , and Staphylococcus . New taxa related to the genera Agrococcus and Leucobacter were found. Yeast and Gram-positive bacteria strains deliberately added as smearing agents were sometimes undetected during ripening. Thirty-two percent of the isolates were Gram-negative bacteria, which showed a high level of diversity and mainly included members of the genera Alcaligenes , Hafnia , Proteus , Pseudomonas , and Psychrobacter . Whatever the milk used (pasteurized or unpasteurized), similar levels of biodiversity were observed in the three dairies, all of which had efficient cleaning procedures and good manufacturing practices. It appears that some of the Gram-negative bacteria identified should now be regarded as potentially useful in some cheese technologies. The assessment of their positive versus negative role should be objectively examined.