Microbulbifer litoralis sp. nov., Isolated from Seashore of Weizhou Island

A bacterium designated GXH0434T was isolated from sea shore samples collected from Weizhou Island, Beihai, Guangxi, China. The organism is motile, strictly aerobic, and possesses a rod-coccus cell cycle in association with the growth phase. It can grow at 15-45 °C (optimum 37 °C), at pH 6.0-11.0 (optimum 6.0), and at 0-20% (w/v) NaCl (optimum 5.0-8.0%). The strain is positive for peroxidase and oxidase activity, negative for Voges-Proskauer test, can hydrolyze Tween 20, Tween 60, Tween 80, casein, and is able to produce siderophore and has the function of nitrogen fixation. Molecular phylogenetic analysis based on 16S rRNA gene sequences indicated that GXH0434T was most closely related to Microbulbifer halophilus KCTC 12848T with the similarity of 97.2%, followed by Microbulbifer chitinilyticus JCM 16148T (97.1%) and Microbulbifer taiwanensis LMG 26125T (96.5%). The digital DNA-DNA hybridization and the average nucleotide identity values between GXH0434T and Microbulbifer halophilus KCTC 12848T were 28.90% and 83.38%, respectively, which were below thresholds of species delineation. The genomic DNA G+C content of the strain was 61.9%. The major fatty acids were iso-C15:0, C16:0, iso-C11:0 3-OH, iso-C11:0 and Summed features 8 (C18:0 ω7c and/or C18:0 ω6c). The major polar lipids detected in GXH0434T were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC). The major respiratory quinone was ubiquinone Q-8. Based on the above polyphasic classification indicated strain GXH0434T represents a novel species of the genus Microbulbifer, for which the name Microbulbifer litoralis sp. nov. is proposed. The type strain is GXH0434T (= MCCC 1K07158T = KCTC 92169T).

Nesterenkonia marinintestina sp. nov., isolated from the fish intestine

A Gram-positive, aerobic, non-motile, irregular short rod, nonspore-forming actinobacterial strain, designated GX14115T, was isolated from fish intestine in Beihai City, Guangxi, China and subjected to a taxonomic polyphasic investigation. Colonies were yellow‒green, circular, smooth, central bulge, convex, opaque and 2.0-3.0 mm in diameter after growth on 2216E medium at 30 °C for 72 h. Growth occurred at 4-45 °C (optimum 30 °C), at pH 4.5-10.0 (optimum pH 7.5) and in the presence of 0-12% NaCl (w/v) (optimum 3.5%). Chemotaxonomic analysis showed that the main menaquinone of strain GX14115T was MK-7. The major cellular fatty acids were anteiso-C15:0 (44.8%), anteiso-C17:0 (20.5%), and iso-C15:0 (16%). The whole-cell sugars were galactose and xylose. The peptidoglycan type was L-Lys-Gly-D-Asp, and the polar lipids were phosphatidylethanolamine (PE), diphosphatidylglycerol (DPG), one unknown phospholipid (UP), and one unknown glycolipid (UG). The DNA G + C content of the type of strain was 69.5 mol%. The 16S rRNA gene sequence analysis revealed that strain GX14115T is affiliated with the genus Nesterenkonia and is closely related to Nesterenkonia sandarakina YIM 70009T (96.5%) and Nesterenkonia lutea YIM 70081T (96.8%). The calculated results indicated that the average nucleotide identity (ANI) values of GX14115T were 74.49-74.78%, to the two aforementioned type strains, and the digital DNA-DNA hybridization (dDDH) values were 20.1-20.7%. Strain GX14115T was proposed as a novel species of the genus Nesterenkonia by the physiological, chemotaxonomic, and phylogenetic data, for whose the name is Nesterenkonia marinintestina sp. nov. The type of strain is GX14115T (= MCCC 1K06658T = KCTC 49495T).

Paenibacillus glufosinatiresistens sp. nov., a glufosinate-resistant bacterium isolated from sludge

A Gram-stain-positive bacterium capable of resisting 5.0 mM glufosinate, designated strain YX-27T, was isolated from a sludge sample collected from a factory in Wuxi, Jiangsu, PR China. Cells were rod-shaped, facultatively anaerobic, endospore-forming, and motile by peritrichous flagella. Growth was observed at 15-42 °C (optimum at 30 °C), pH 4.0-8.0 (optimum pH 7.0-7.5) and with 0-2.5% NaCl (w/v; optimum, 0.5 %). Strain YX-27T could tolerate up to 6.0 mM glufosinate. Strain YX-27T showed the highest 16S rRNA gene sequence similarity to Paenibacillus tianjinensis TB2019T (96.17 %), followed by Paenibacillus odorifer DSM 1539T (96.15 %), Paenibacillus sophorae S27T (96.04 %), Paenibacillus apii 7124T (96.02 %) and Paenibacillus stellifer DSM 14472T (95.87 %). The phylogenetic tree based on genome and 16S rRNA gene sequences indicated that strain YX-27T was clustered in the genus Paenibacillus but formed a separate clade. The genome size of YX-27T was 5.22 Mb with a G+C content of 57.5 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between the genomes of strain YX-27T and 12 closely related type strains ranged from 70.8 to 74.8% and 19.8 to 23.0 %, respectively. The major cellular fatty acids were C16 : 0, anteiso-C15 : 0 and iso-C16 : 0. The major polar lipids were one diphosphatidylglycerol, one phosphatidylethanolamine, one phosphatidylglycerol, one phospholipid, four aminophospholipids and four unidentified lipids. The predominant respiratory quinone was MK-7. Based on phylogenetic, genomic, chemotaxonomic and phenotypic data, strain YX-27T was considered to represent a novel species for which the name Paenibacillus glufosinatiresistens sp. nov. is proposed, with YX-27T (=MCCC 1K08803T= KCTC 43611T) as the type strain.

Bacillus pinisoli sp. nov., Isolated from Soil of a Decayed Pine Tree

A Gram-stain-positive, rod-shaped, facultatively anaerobic, motile and spore-forming bacterium with multiple flagella designated GXH0341^T was isolated from the soil associated with decayed pine tree samples collected from Weizhou Island, Beihai, Guangxi, China. Growth occurred at 4-37 °C (optimum 30 °C), at pH 5.0-11.0 (optimum 8.0) and in the presence of 0-7% (w/v) NaCl (optimum 2%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GXH0341^T was most closely related to Bacillus mesophilus DSM 101000 ^T (98.9%), followed by Bacillus salitolerans KC1^T (96.95%) and Margalitia shackletonii DSM 18435 ^T (96.67%). Phylogenetic analysis revealed that strain GXH0341^T represented a separate lineage within the genus Bacillus. Peroxidase is positive. The predominant quinone was MK-7 and the cell-wall diagnostic diamino acid was meso-diaminopimelic acid. The predominant polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, and two unidentified phospholipids. The major fatty acids are iso-C_14:0, iso-C_15:0, anteiso-C_15:0 and iso-C_16:0. The genome of GXH0341^T comprises the biosynthetic gene cluster for T3PKS, terpene, lassopeptide and RRE-containing element as secondary metabolites. The average nucleotide identity values and the digital DNA-DNA hybridization values between GXH0341^T and B. mesophilus DSM 101000 ^T were 78.22% and 21.00%, respectively, which were in the range of the recommended level for interspecies identity. The results of phenotypic, chemotaxonomic and genotypic analyses clearly indicated strain GXH0341^T represents a novel species of the genus Bacillus, for which the name Bacillus pinisoli sp. nov. is proposed. The type strain is GXH0341^T (= MCCC 1K07157^T = JCM 35212 ^T).

Metabacillus kandeliae sp. nov., isolated from the rhizosphere soil of a decayed mangrove plant Kandelia candel

In this study, we isolated a novel Gram-stain-positive, aerobic, motile, rod-shaped bacterium, named GX 13764T, from the rhizosphere soil of a decayed mangrove plant Kandelia candel collected from Beihai, Guangxi, PR China, and characterized using a polyphasic taxonomic approach. The strain exhibited yellow-orange, round, convex, shiny, smooth, opaque and 2–3 mm diameter colonies on marine agar 2216 media after 3 days of incubation at 30 °C and was capable of growth at 4–45 °C (optimum, 30 °C), pH 5.0–9.0 (optimum, pH 7.0) and 0–4 % NaCl (w/v; optimum, 2 %). The strain was positive for catalase and negative for the oxidase. The main cellular fatty acid was anteiso-C15:0, iso-C15:0, iso-C16:0 and iso-C14:0. The cell-wall peptidoglycan comprised meso-diaminopimelic acid and the main menaquinone was MK-7. The polar lipids included one diphosphatidylglycerol, one phosphatidylglycerol, two glycolipids, two unidentified phospholipids and three unidentified lipids. Based on 16S rRNA gene analysis, GX 13764T presented the highest sequence similarity to Metabacillus mangrovi KCTC 33872T (97.04 %). The DNA G+C content of the type strain was 44.2 mol%. The average nucleotide identity values between GX 13764T and M. mangrovi KCTC 33872T, Metabacillus idriensis DSM 19097T and Metabacillus indicus LMG 22858T were 69.39, 68.87 and 68.95 %, respectively, with digital DNA–DNA hybridization values of 19.9, 19.5 and 19.5 %, respectively. Based on the polyphasic data, strain GX 13764T should be nominated as a novel species of the genus Metabacillus , for which the name Metabacillus kandeliae sp. nov. is proposed. The type strain is GX 13764T (=MCCC 1K06654T=KCTC 43366T).

Paenibacillus sinensis sp. nov., a nitrogen-fixing species isolated from plant rhizospheres

Two strains HN-1^T and 39 were isolated from rhizospheres of different plants grown in different regions of PR China. The two strains exhibited high nitrogenase activities and possessed almost identical 16S rRNA gene sequences. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 99.9 and 99.8%, respectively, suggesting that they belong to one species. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strains HN-1^T and 39 are the members of the genus Paenibacillus and both strains exhibited 99.5% similarity to Paenibacillus stellifer DSM 14472^T and the both strains represented a separate lineage from all other Paenibacillus species. However, the ANI of type strain HN-1^T with P. stellifer DSM 14472^T was 90.69, which was below the recommended threshold value (< 95-96% ANI). The dDDH showed 42.1% relatedness between strain HN-1^T and P. stellifer DSM 14472^T, which was lower than the recommended threshold value (dDDH < 70%). The strain HN-1^T contain anteiso-C_15:0 as major fatty acids and MK-7 as predominant isoprenoid quinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four aminophospholipids and an unidentified glycolipid. Unlike the most closely related P. stellifer DSM 14472^T, strain HN-1^T or 39 was positive for catalase reaction. Distinct phenotypic and genomic characterisations from previously described taxa support the classification of strains HN-1^T or 39 as representatives of a novel species of the genus Paenibacillus, for which the name Paenibacillus sinensis is proposed, with type strains HN-1^T (=CGMCC 1.18902, JCM 34,620), and reference strain 39 (=CGMCC 1.18879, JCM 34,616), respectively.

Paraliobacillus salinarum sp. nov., isolated from saline soil in Yingkou, China

A novel Gram-stain-positive, facultatively aerobic, slightly halophilic, endospore-forming bacterium, designated G6-18^T, was isolated from saline soil collected in Yingkou, Liaoning, PR China. Cells of strain G6-18^T grew at 10-37 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 8.0) and in the presence of 2-15 % (w/v) NaCl (optimum, 5 %). The strain could be clearly distinguished from the related species of the genus Paraliobacillus by its phylogenetic position and biochemical characteristics. It presented MK-7 as the major quinone and the dominant cellular fatty acids were iso-C_16 : 0, anteiso-C_15 : 0, C_16 : 0 and iso-C_14 : 0. The polar lipids consisted of diphosphatidylglycerol and phosphatidylglycerol as the major components. The G+C content of strain G6-18^T genome was 35.3 mol%. 16S rRNA analysis showed that strain G6-18^T had the highest similarity to Paraliobacillus ryukyuensis DSM 15140^T, reaching 97.0 %, followed by Paraliobacillus quinghaiensis CGMCC 1.6333^T with a value of 96.3 %. The average nucleotide identity values between strain G6-18^T and Paraliobacillus ryukyuensis DSM 15140^T, Paraliobacillus sedimins KCTC 33762^T, Paraliobacillus quinghaiensis CGMCC 1.6333^T and Paraliobacillus zengyii DSM 107811^T were 74.3, 72.0, 73.2 and 72.8 %, respectively, and the digital DNA-DNA hybridization values between strain G6-18^T and the neighbouring strains were 15.6, 13.8, 14.2 and 14.2 %, respectively. Based on phenotypic, chemotaxonomic and phylogenetic inferences, strain G6-18^T represents a novel species of the genus Paraliobacillus, for which the name Paraliobacillus salinarum sp. nov. (=CGMCC 1.12058^T=DSM 25428^T) is proposed.

Flavimobilis rhizosphaerae sp. nov., isolated from rhizosphere soil of Spartina alterniflora

A novel Gram-stain positive, facultatively anaerobic, motile, irregularly rod-shaped bacterium, designated GY 10621^T, was isolated from rhizosphere soil of Spartina alterniflora in Beihai City, Guangxi Province, PR China, and characterized using a polyphasic taxonomic approach. GY 10621^T was positive for catalase and oxidase. Growth occurred at 4-42 °C (optimum 30-37 °C), at pH 5.0-9.0 (optimum pH 7.0) and in the presence of 0-5% NaCl (w/v) (optimum 1-3%). The main menaquinones were MK-9 (H₄) (92.2 %) and MK-10 (7.8 %). The major cellular fatty acids were anteiso-C_15 : 0 and C_14 : 0. The peptidoglycan was the type A4α (l-Lys-Ser-d-Glu). The polar lipids included four phosphoglycolipids, four glycolipids, an unidentified lipid and six unidentified phospholipids. The DNA G+C content of the type strain was 71.7 mol%. On the basis of the results of 16S rRNA gene analysis, the type strain of a species with a validly published name with the highest similarity to GY 10621^T was Flavimobilis soli KCTC 13155^T (97.16 %), followed by Sanguibacter suarezii NBRC 16159^T (96.39 %). The calculated results indicated that compared with GY 10621^T, the average nucleotide identity (ANI) values of three strains closely related to GY 10621^T (the two aforementioned type strains and 'S. massiliensis' Marseille-P3815) were 74.18-94.97 %, and the digital DNA-DNA hybridization (dDDH) values were 20.3-60.6 %. The results of 16S rRNA-based and genome-based phylogenetic tree analysis indicated that GY 10621^T should be assigned to the genus Flavimobilis. On the basis of evidence from polyphasic studies, GY 10621^T should be designated as representing a novel species of the genus Flavimobilis, for which the name Flavimobilis rhizosphaerae sp. nov. is proposed. The type strain is GY 10621^T (=CGMCC 1.17411^T=KCTC 49515^T).

Enterococcus faecalis Readily Adapts Membrane Phospholipid Composition to Environmental and Genetic Perturbation

The bacterial lipid membrane, consisting both of fatty acid (acyl) tails and polar head groups, responds to changing conditions through alteration of either the acyl tails and/or head groups. This plasticity is critical for cell survival as it allows maintenance of both the protective nature of the membrane as well as functioning membrane protein complexes. Bacteria that live in fatty-acid rich environments, such as those found in the human host, can exploit host fatty acids to synthesize their own membranes, in turn, altering their physiology. Enterococcus faecalis is such an organism: it is a commensal of the mammalian intestine where it is exposed to fatty-acid rich bile, as well as a major cause of hospital infections during which it is exposed to fatty acid containing-serum. Within, we employed an untargeted approach to detect the most common phospholipid species of E. faecalis OG1RF via ultra-high performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). We examined not only how the composition responds upon exposure to host fatty acids but also how deletion of genes predicted to synthesize major polar head groups impact lipid composition. Regardless of genetic background and differing basal lipid composition, all strains were able to alter their lipid composition upon exposure to individual host fatty acids. Specific gene deletion strains, however, had altered survival to membrane damaging agents. Combined, the enterococcal lipidome is highly resilient in response to both genetic and environmental perturbation, likely contributing to stress survival.

Integrated into Environmental Biofilm Chromobacterium vaccinii Survives Winter with Support of Bacterial Community

Chromobacterium species are common in tropical and subtropical zones in environmental samples according to numerous studies. Here, we describe an environmental case of resident Chromobacterium vaccinii in biofilms associated with Carex spp. roots in Moscow region, Russia (warm-summer humid continental climate zone). We performed broad characterization of individual properties as well as surrounding context for better understanding of the premise of C. vaccinii survival during the winter season. Genome properties of isolated strains propose some insights into adaptation to habit and biofilm mode of life, including social cheaters carrying ΔluxR mutation. Isolated C. vaccinii differs from previously described strains in some biochemical properties and some basic characteristics like fatty acid composition as well as unique genome features. Despite potential to modulate membrane fluidity and presence of several genes responsible for cold shock response, isolated C. vaccinii did not survive during exposure to 4 °C, while in the complex biofilm sample, it was safely preserved for at least half a year in vitro at 4 °C. The surrounding bacterial community within the same biofilm with C. vaccinii represented a series of psychrophilic bacterial species, which may share resistance to low temperatures with other species within biofilm and provide C. vaccinii an opportunity to survive during the cold winter season.

Induction of Daptomycin Tolerance in Enterococcus faecalis by Fatty Acid Combinations

With an increasing prevalence of antibiotic resistance in the clinic, we strive to understand more about microbial defensive mechanisms. A nongenetic tolerance to the antibiotic daptomycin was discovered in Enterococcus faecalis that results in the increased survival of bacterial populations after treatment with the drug. This tolerance mechanism likely synergizes with antibiotic resistance in the clinic. Given that this tolerance phenotype is induced by incorporation of fatty acids present in the host, it can be assumed that infections by this organism require a higher dose of antibiotic for successful eradication. The mixture of fatty acids in human fluids is quite diverse, with little understanding between the interplay of fatty acid combinations and the tolerance phenotype we observe. It is crucial to understand the effects of fatty acid combinations on E. faecalis physiology if we are to suppress the tolerance physiology in the clinic.

Enterococcus faecalis is a Gram-positive bacterium that normally exists as an intestinal commensal in humans but is also a leading cause of nosocomial infections. Previous work noted that growth supplementation with serum induced tolerance to membrane-damaging agents, including the antibiotic daptomycin. Specific fatty acids found within serum could independently provide tolerance to daptomycin (protective fatty acids), yet some fatty acids found in serum did not and had negative effects on enterococcal physiology (nonprotective fatty acids). Here, we measured a wide array of physiological responses after supplementation with combinations of protective and nonprotective fatty acids to better understand how serum induces daptomycin tolerance. When cells were supplemented with either nonprotective fatty acid, palmitic acid, or stearic acid, there were marked defects in growth and morphology, but these defects were rescued upon supplementation with either protective fatty acid, oleic acid, or linoleic acid. Membrane fluidity decreased with growth in either palmitic or stearic acid alone but returned to basal levels when a protective fatty acid was supplied. Daptomycin tolerance could be induced if a protective fatty acid was provided with a nonprotective fatty acid, and some specific combinations protected as well as serum supplementation. While cell envelope charge has been associated with tolerance to daptomycin in other Gram-positive bacteria, we concluded that it does not correlate with the fatty acid-induced protection we observed. Based on these observations, we conclude that daptomycin tolerance by serum is driven by specific, protective fatty acids found within the fluid.

IMPORTANCE With an increasing prevalence of antibiotic resistance in the clinic, we strive to understand more about microbial defensive mechanisms. A nongenetic tolerance to the antibiotic daptomycin was discovered in Enterococcus faecalis that results in the increased survival of bacterial populations after treatment with the drug. This tolerance mechanism likely synergizes with antibiotic resistance in the clinic. Given that this tolerance phenotype is induced by incorporation of fatty acids present in the host, it can be assumed that infections by this organism require a higher dose of antibiotic for successful eradication. The mixture of fatty acids in human fluids is quite diverse, with little understanding between the interplay of fatty acid combinations and the tolerance phenotype we observe. It is crucial to understand the effects of fatty acid combinations on E. faecalis physiology if we are to suppress the tolerance physiology in the clinic.

Effects of cell physiological structure on the fermentation broth viscosity during poly-γ-glutamic acid production by Bacillus subtilis GXA-28

The high viscosity of fermentation broth limited the further improvement of PGA titer. Our previous studies indicated that adding KCl to the medium could decrease the fermentation broth viscosity and improve the PGA titer. In order to clarify the reason, effects of cell physiological structure on the fermentation broth viscosity were investigated. Results from cell morphology observation showed that the reduction of cell aggregation caused by the weakened cross-linking between PGA and cells might be an important reason for the decrease in the fermentation broth viscosity. Besides, when 201.2 mM KCl was added to the medium, the zeta potential of cell surface decreased from - 70.48 ± 3.35 mV to - 81 ± 2.46 mV. The cell membrane integrity was reduced and permeability was enhanced. Furthermore, the percentage of lauric acid C12:0 in cell membrane increased by 12.36%, but palmitic acid C16:0 and stearic acid C18:0 decreased by 6.83% and 5.64%, respectively, which improved the fluidity of cell membrane. The above changes in cell membrane further affect the cross-linking between PGA and cells, thereby playing an important role in reducing the fermentation broth viscosity. This study provided some novel information for understanding the decrease of PGA fermentation broth viscosity by KCl.

Frigidibacter oleivorans sp. nov., isolated from a deep well with oil reservoir water

A Gram-stain-negative, rod-shaped bacterium, designated XJ4^T, was isolated from oil-contaminated water, collected from Xinjiang Province, north-west PR China (45° 1' 27″ N, 85° 6' 14″ E). Growth occurred at 20-45 °C (optimum, 30 °C) and pH 6.0-10.0 (optimum, pH 6.0-7.0). Strain XJ4^T could tolerate up to 7 % (w/v) NaCl and grow optimally in the absence of NaCl. Phylogenetic analysis based on comparative sequence analysis of 16S rRNA gene sequences indicated that strain XJ4^T belonged to the genus Frigidibacter, and that was closely related to Frigidibacter mobilis cai42^T (97.2 %), Frigidibacter albus SP32^T (97.0 %) and Rhodobacter aestuarii JA296^T (97.0 %). The average nucleotide identity values between XJ4^T and three type strains were 77.9, 77.6 and 71.9 %, respectively. The DNA G+C content of strain XJ4^T was 69.5 mol%. The sole respiratory quinone was Q-10. The major cellular fatty acid was summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c), C_18 : 0 and 11-methyl C_18 : 1  ω7c. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, an unidentified aminolipid and unidentified lipids. On the basis of phenotypic, chemotaxonomic and phylogenetic analyses, strain XJ4^T represents a novel species of the genus Frigidibacter, for which the name Frigidibacter oleivorans sp. nov. is proposed. The type strain is XJ4^T (=CGMCC 1.13778^T=LMG 30952^T).

Paracoccus alkanivorans sp. nov., isolated from a deep well with oil reservoir water

A Gram-stain-negative, non-motile and ovoid bacterial strain, designated 4-2T, was isolated from oil-contaminated water which was collected from Xinjiang Province, north-west PR China. The 16S rRNA gene sequence analysis showed that strain 4-2T belonged to the genus Paracoccus . The species with highest similarity to strain 4-2T was Paracoccus saliphilus YIM 90738T (97.83 %), followed by ‘ Paracoccus siganidrum ’ M26 (97.83 %) and Paracoccus endophyticus SYSUP0003T (97.25 %). The average nucleotide identity values between 4-2T and three type strains were 84.69, 77.88 and 74.07 %, respectively. The genomic DNA G+C content of strain 4-2T was 61.4 mol%. Chemotaxonomical characteristic results showed that the respiratory quinone was ubiquinone Q-10 and the major fatty acids were summed feature 8 (C18 : 1 ω7c or C18 : 1 ω6c) and C19 : 0 cyclo ω8c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, unidentified phospholipids, an unidentified aminolipid and an unidentified polar lipid. The predominant polyamines were putrescine, cadaverine and spermidine. On the basis of phenotypic, chemotaxonomic and phylogenetic inferences, strain 4-2T represents a novel species of the genus Paracoccus , for which the name Paracoccus alkanivorans sp. nov. is proposed. The type strain is 4-2T (=CGMCC 1.13669T=LMG 30882T).

Paenibacillus maysiensis sp. nov., a Nitrogen-Fixing Species Isolated from the Rhizosphere Soil of Maize

A novel bacterium SX-49^T with nitrogen-fixing capability was isolated from the rhizosphere soil of maize. Phylogenetic analysis of nifH gene fragment and 16S rRNA gene sequence revealed that the strain SX-49^T is a member of the genus Paenibacillus. Values of 16S rRNA gene sequence similarity were highest between SX-49^T and P. jamilae DSM 13815^T (97.0%), P. brasiliensis DSM 14914^T (97.8%), P. polymyxa DSM 36^T (97.5%), and P. terrae DSM 15891^T (98.8%). The similarity between SX-49^T and other Paenibacillus species was < 97.0%. DNA-DNA hybridization values between strain SX-49^T and the four type strains were P. jamilae DSM 13815^T: 40.6%, P. brasiliensis DSM 14914^T: 27.9%, P. polymyxa DSM 36^T: 29.2%, and P. terrae DSM 15891^T: 66.4%. The DNA G+C content of SX-49^T was 46.4 mol%. The predominant fatty acids were anteiso-C_15:0, C_16:0 and iso-C_16:0. The predominant isoprenoid quinone was MK-7. The genome contains 5628 putative protein-coding sequences (CDS), 6 rRNAs and 56 tRNAs. The phenotypic and genotypic characteristics, DNA-DNA relatedness, and genome features suggest that SX-49^T represents a novel species of the genus Paenibacillus, and the name Paenibacillus maysiensis sp. nov. is proposed.

Enterococcus faecalis Responds to Individual Exogenous Fatty Acids Independently of Their Degree of Saturation or Chain Length

Enterococcus faecalis is a commensal of the human gastrointestinal tract that can persist in the external environment and is a leading cause of hospital-acquired infections. Given its diverse habitats, the organism has developed numerous strategies to survive a multitude of environmental conditions. Previous studies have demonstrated that E. faecalis will incorporate fatty acids from bile and serum into its membrane, resulting in an induced tolerance to membrane-damaging agents. To discern whether all fatty acids induce membrane stress protection, we examined how E. faecalis responded to individually supplied fatty acids. E. faecalis readily incorporated fatty acids 14 to 18 carbons in length into its membrane but poorly incorporated fatty acids shorter or longer than this length. Supplementation with saturated fatty acids tended to increase generation time and lead to altered cellular morphology in most cases. Further, exogenously supplied saturated fatty acids did not induce tolerance to the membrane-damaging antibiotic daptomycin. Supplementation with unsaturated fatty acids produced variable growth effects, with some impacting generation time and morphology. Exogenously supplied unsaturated fatty acids that are normally produced by E. faecalis and those that are found in bile or serum could restore growth in the presence of a fatty acid biosynthetic inhibitor. However, only the eukaryote-derived fatty acids oleic acid and linoleic acid provided protection from daptomycin. Thus, exogenous fatty acids do not lead to a common physiological effect on E. faecalis. The organism responds uniquely to each, and only host-derived fatty acids induce membrane protection.

IMPORTANCEEnterococcus faecalis is a commonly acquired hospital infectious agent with resistance to many antibiotics, including those that target its cellular membrane. We previously demonstrated that E. faecalis will incorporate fatty acids found in human fluids, like serum, into its cellular membrane, thereby altering its membrane composition. In turn, the organism is better able to survive membrane-damaging agents, including the antibiotic daptomycin. We examined fatty acids commonly found in serum and those normally produced by E. faecalis to determine which fatty acids can induce protection from membrane damage. Supplementation with individual fatty acids produced a myriad of different effects on cellular growth, morphology, and stress response. However, only host-derived unsaturated fatty acids provided stress protection. Future studies are aimed at understanding how these specific fatty acids induce protection from membrane damage.

Isolation and characterization of Kingella negevensis sp. nov., a novel Kingella species detected in a healthy paediatric population

We herein report the isolation and characterization of 21 Gram-stain-negative strains cultivated from the oropharynx of healthy children in Israel and Switzerland. Initially described as small colony variants of Kingella kingae, phenotypic analysis, biochemical analysis, phylogenetic analysis based on sequencing of the partial 16S rRNA gene and five housekeeping genes (abcZ, adk, G6PD, groEL and recA), and whole genome sequencing and comparison between members of the genera Kingella and Neisseria provided evidence for assigning them to the genus Kingella. Cellular fatty acids included important amounts of C12 : 0, C14 : 0, C16 : 0 and C16 : 1n7. Digital DNA-DNA hybridization between the isolates Sch538T and K. kingae ATCC 23330T revealed relatedness of 19.9 %. Comparative analysis of 16S rRNA gene sequences available in GenBank allowed matches to strains isolated in the USA, suggesting a wider geographical distribution. A novel species named Kingella negevensis sp. nov. is proposed, as most strains have been isolated in the Negev, a desert region of southern Israel. The type strain is Sch538T (=CCUG 69806T=CSUR P957).

Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium

Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms.

Exogenous Fatty Acids Protect Enterococcus faecalis from Daptomycin-Induced Membrane Stress Independently of the Response Regulator LiaR

Enterococcus faecalis is a commensal bacterium of the gastrointestinal tract that can cause nosocomial infections in immunocompromised humans. The hallmarks of this organism are its ability to survive in a variety of stressful habitats and, in particular, its ability to withstand membrane damage. One strategy used by E. faecalis to protect itself from membrane-damaging agents, including the antibiotic daptomycin, involves incorporation of exogenous fatty acids from bile or serum into the cell membrane. Additionally, the response regulator LiaR (a member of the LiaFSR [lipid II-interacting antibiotic response regulator and sensor] system associated with cell envelope stress responses) is required for the basal level of resistance E. faecalis has to daptomycin-induced membrane damage. This study aimed to determine if membrane fatty acid changes could provide protection against membrane stressors in a LiaR-deficient strain of E. faecalis We noted that despite the loss of LiaR, the organism readily incorporated exogenous fatty acids into its membrane, and indeed growth in the presence of exogenous fatty acids increased the survival of LiaR-deficient cells when challenged with a variety of membrane stressors, including daptomycin. Combined, our results suggest that E. faecalis can utilize both LiaR-dependent and -independent mechanisms to protect itself from membrane damage.

IMPORTANCE

Enterococcus faecalis is responsible for a significant number of nosocomial infections. Worse, many of the antibiotics used to treat E. faecalis infection are no longer effective, as this organism has developed resistance to them. The drug daptomycin has been successfully used to treat some of these resistant strains; however, daptomycin-resistant isolates have been identified in hospitals. Many daptomycin-resistant isolates are found to harbor mutations in the genetic locus liaFSR, which is involved in membrane stress responses. Another mechanism shown to increase tolerance to daptomycin involves the incorporation of exogenous fatty acids from host fluids like serum or bile. This improved tolerance was found to be independent of liaFSR and suggests that there are additional ways to impact sensitivity to daptomycin. Thus, further studies are needed to understand how host fatty acid sources can influence antibiotic susceptibility.

Description of strain FC3T as the neotype strain of Actinobaculum massiliense

Actinobaculum massiliense (Euzéby, 2006) was isolated from the urine of an elderly woman in 2001. Unfortunately, the strain deposited as the type strain was, by error, an Actinobaculum schaalii strain (Yassin et al., 2015). In 2015, we isolated a new strain of A. massiliense, FC3, from the urine of a 12-year-old patient with acute cystitis. We herein present the characteristics of strain FC3 (=CSUR P1982=DSM 100580) and formally propose it as the neotype strain of A. massiliense.

Mass spectrometry tools and workflows for revealing microbial chemistry

Since the time Van Leeuwenhoek was able to observe microbes through a microscope, an innovation that led to the birth of the field of microbiology, we have aimed to understand how microorganisms function, interact and communicate. The exciting progress in the development of analytical technologies and workflows has demonstrated that mass spectrometry is a very powerful technique for the interrogation of microbiology at the molecular level. In this review, we aim to highlight the available and emerging tools in mass spectrometry for microbial analysis by overviewing the methods and workflow advances for taxonomic identification, microbial interaction, dereplication and drug discovery. We emphasize their potential for future development and point out unsolved problems and future directions that would aid in the analysis of the chemistry produced by microbes.

Incorporation of exogenous fatty acids protects Enterococcus faecalis from membrane-damaging agents

Enterococcus faecalis is a commensal bacterium of the mammalian intestine that can persist in soil and aquatic systems and can be a nosocomial pathogen to humans. It employs multiple stress adaptation strategies in order to survive such a wide range of environments. Within this study, we sought to elucidate whether membrane fatty acid composition changes are an important component for stress adaptation. We noted that E. faecalis OG1RF was capable of changing its membrane composition depending upon growth phase and temperature. The organism also readily incorporated fatty acids from bile, serum, and medium supplemented with individual fatty acids, often dramatically changing the membrane composition such that a single fatty acid was predominant. Growth in either low levels of bile or specific individual fatty acids was found to protect the organism from membrane challenges such as high bile exposure. In particular, we observed that when grown in low levels of bile, serum, or the host-derived fatty acids oleic acid and linoleic acid, E. faecalis was better able to survive the antibiotic daptomycin. Interestingly, the degree of membrane saturation did not appear to be important for protection from the stressors examined here; instead, it appears that a specific fatty acid or combination of fatty acids is critical for stress resistance.

Visualized analysis of cellular fatty acid profiles of Vibrio parahaemolyticus strains under cold stress

Vibrio parahaemolyticus is a common foodborne bacterial pathogen, which survives in cold environments and is sometimes difficult to culture. Fatty acid analysis under cold stress was conducted for several V. parahaemolyticus strains using gas chromatography/mass spectrometry, and the results were compared with those of the controls. All the fatty acid profiles obtained were visualized by multidimensional scaling (MDS) and self-organized map (SOM). It was observed that the fatty acid profiles of V. parahaemolyticus substantially changed under cold stress. The percentage of methyl palmitate remarkably decreased and that of methyl palmitoleate (except for two strains) and methyl oleate increased. These findings demonstrate the role of fatty acids in cold stress. The changes in the fatty acid profiles illustrated by MDS and SOM could differentiate strains under cold stress from the controls and can potentially lead to a method of detecting injured cold-stressed V. parahaemolyticus.

UV-C pre-adaptation of Salmonella: effect on cell morphology and membrane fatty acids composition

The present study was carried out to evaluate the effects of ultraviolet radiations (UV-C) on the fatty acids composition of three serovars of Salmonella: S. typhimurium, S. hadar and S. zanzibar. Results obtained show that UV-C treatment increases significantly (P ≤ 0.05) the percentage of cyclic fatty acids. The atomic force microscopy was used to study the morphology and cell surface of irradiated strains. Results show that UV-C rays induce morphological changes and alter the bacterial cell surface (presence of grooves and irregularities).

Paenibacillus beijingensis sp. nov., a nitrogen-fixing species isolated from wheat rhizosphere soil

A novel nitrogen-fixing bacterium, BJ-18(T), was isolated from wheat rhizosphere soil. Strain BJ-18(T) was observed to be Gram-positive, facultatively anaerobic, motile and rod-shaped (0.4-0.9 μm × 2.0-2.9 μm). Phylogenetic analysis based on a partial nifH gene sequence and an assay for nitrogenase activity showed its nitrogen-fixing capacity. Phylogenetic analysis based on full 16S rRNA gene sequences suggested that strain BJ-18(T) is a member of the genus Paenibacillus. High similarity of 16S rRNA gene sequence was found between BJ-18(T) and Paenibacillus peoriae DSM 8320(T) (99.05 %), Paenibacillus jamilae DSM 13815(T) (98.86 %), Paenibacillus brasiliensis DSM 13188(T) (98.55 %), Paenibacillus polymyxa DSM 36(T) (98.74 %), Paenibacillus terrae DSM 15891(T) (97.99 %) and Paenibacillus kribbensis JCM 11465(T) (97.92 %), whereas the similarity was below 96.0 % between BJ-18(T) and the other Paenibacillus species. DNA-DNA relatedness between strain BJ-18(T) and P. peoriae DSM 8320(T), P. jamilae DSM 13815(T), P. brasiliensis DSM 13188(T), P. polymyxa DSM 36(T), P. kribbensis JCM 11465(T) and P. terrae DSM 15891(T) was determined to be 43.6 ± 2.7, 34.2 ± 5.3, 47.9 ± 6.6, 36.8 ± 3.5, 27.4 ± 4.3 and 23.6 ± 4.1 % respectively. The DNA G+C content of BJ-18(T) was determined to be 45.8 mol %. The major fatty acid was identified as anteiso-C15:0 (67.1 %). The polar lipids present in strain BJ-18(T) were identified as diphosphatidylglycerol, phosphatidyl methylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. The phenotypic and genotypic characteristics, and DNA-DNA relatedness data, suggest that BJ-18(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus beijingensis sp. nov. (Type strain BJ-18(T)=DSM25425(T)=CGMCC 1.12045(T)) is proposed.

Acinetobacter puyangensis sp. nov., isolated from the healthy and diseased part of Populus xeuramericana canker bark

Two Gram-negative, non-motile, rod-shaped strains, BQ4-1(T) and NHI3-2, isolated respectively from the healthy and diseased part of Populus ×euramericana canker bark, were characterized using a polyphasic approach. Chemotaxonomic characterization supported the inclusion of the two strains in the genus Acinetobacter, with genomic DNA G+C contents (42.5-43 mol%) within the range observed for this genus (38-47 mol%) and 9-octadecenoic acid (C18 : 1ω9c, 39.87 %), hexadecanoic acid (C16 : 0, 11.26 %) and summed feature 3 (comprising C16 : 1ω7c/C16 : 1ω6c, 18.90 %) as major fatty acids. Phylogenetic analysis based on 16S rRNA, rpoB and gyrB gene sequences revealed that strains BQ4-1(T) and NHI3 did not cluster with any species with validly published names, and formed a distinct cluster with 99-100 % bootstrap support on three phylogenetic trees within the genus Acinetobacter. Acid was not produced from d-glucose, and haemolysis was not observed on agar media supplemented with sheep erythrocytes. On the basis of phenotypic, genotypic and phylogenetic characteristics, the two strains are considered to represent a novel species of the genus Acinetobacter, for which the name Acinetobacter puyangensis sp. nov. is proposed. The type strain is BQ4-1(T) (= CFCC 10780(T) = JCM 18011(T)).

Paenibacillus taohuashanense sp. nov., a nitrogen-fixing species isolated from rhizosphere soil of the root of Caragana kansuensis Pojark

A nitrogen-fixing bacterium, designated strain gs65(T), was isolated from a rhizosphere soil sample of Caragana kansuensis Pojark. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain gs65(T) is a member of the genus Paenibacillus. High levels of 16S rRNA gene similarity were found between strain gs65(T) and Paenibacillus borealis DSM 13188(T) (97.5 %), Paenibacillus odorifer ATCC BAA-93(T) (97.3 %), Paenibacillus durus DSM 1735(T) (97.0 %) and Paenibacillus sophorae DSM23020(T) (96.9 %). Levels of 16S rRNA gene sequence similarity between strain gs65(T) and the type strains of other recognized members of the genus Paenibacillus were below 97.0 %. Levels of DNA-DNA relatedness between strain gs65(T) and P. borealis DSM 13188(T), P. odorifer ATCC BAA-93(T) (97.3 %), P. durus DSM 1735(T) and P. sophorae DSM23020(T) were 35.9, 38.0, 34.2 and 35.5 % respectively. The DNA G+C content of strain gs65(T) was determined to be 51.6 mol%. The major fatty acids were found to be iso-C(14:0), anteiso-C(15:0) and iso-C(16:0). On the basis of its phenotypic characteristics and levels of DNA-DNA hybridization, strain gs65(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus taohuashanense sp. nov. is proposed. The type strain is gs65(T) (=CGMCC 1.12175(T) = DSM 25809(T)).

Spores of Bacillus cereus strain KBAB4 produced at 10 °C and 30 °C display variations in their properties

Spores of the psychrotrophic Bacillus cereus KBAB4 strain were produced at 10 °C and 30 °C in fermentors. Spores produced at 30 °C were more resistant to wet heat at 85 °C, 1% glutaraldehyde, 5% hydrogen peroxide, 1M NaOH and pulsed light at fluences between 0.5 and 1.75 Jcm(-2) and to a lesser extent to monochromatic UV-C at 254 nm. No difference in resistance to 0.25 mM formaldehyde, 1M nitrous acid and 0.025 gl(-1) calcium hypochlorite was observed. Spores produced at 10 °C germinated more efficiently with 10 mM and 100 mM l-alanine than spores produced at 30 °C, while no difference in germination was observed with inosine. Dipicolinic acid (DPA) content in the spore was significantly higher for spores prepared at 30 °C. Composition of certain fatty acids varied significantly between spores produced at 10 °C and 30 °C.

Paenibacillus jilunlii sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Begonia semperflorens

A nitrogen-fixing bacterium, designated strain Be17(T), was isolated from rhizosphere soil of Begonia semperflorens planted in Beijing Botanical Garden, PR China. Phylogenetic analyses based on a segment of the nifH gene sequence and a full-length 16S rRNA gene sequence revealed that strain Be17(T) was a member of the genus Paenibacillus. High levels of 16S rRNA gene sequence similarity were found between strain Be17(T) and Paenibacillus graminis RSA19(T) (97.9 %), Paenibacillus sonchi LMG 24727(T) (97.8 %), Paenibacillus riograndensis CECT 7330(T) (96.2 %) and Paenibacillus borealis DSM 13188(T) (96.1 %), respectively. Levels of 16S rRNA gene sequence similarity between strain Be17(T) and the type strains of other recognized members of the genus Paenibacillus were below 96.0 %. However, the DNA-DNA hybridization values between strain Be17(T) and P. graminis RSA19(T), P. sonchi LMG 24727(T) and P. riograndensis CECT 7330(T) were 47.9 %, 38.7 % and 37.5 %, respectively. The DNA G+C content of strain Be17(T) was 52.9 mol%. The major fatty acid component of strain Be17(T) was anteiso-branched C(15 : 0) (30.92 %). The major isoprenoid quinone was MK-7. The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. On the basis of its phenotypic characteristics, 16S rRNA gene sequences, DNA G+C content, DNA-DNA relatedness, chemotaxonomic properties and nifH gene sequence, strain Be17(T) represents a nitrogen-fixing strain of a novel species of the genus Paenibacillus, for which the name Paenibacillus jilunlii sp. nov. is proposed. The type strain is Be17(T) ( = CGMCC 1.10239(T) = DSM 23019(T)).

Paenibacillus sophorae sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Sophora japonica

A nitrogen-fixing bacterium, designated strain S27(T), was isolated from rhizosphere soil of Sophora japonica. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain S27(T) is a member of the genus Paenibacillus. High levels of 16S rRNA gene sequence similarity were found between strain S27(T) and Paenibacillus durus DSM 1735(T) (97.3 %), Paenibacillus sabinae DSM 17841(T) (96.9 %), Paenibacillus forsythiae DSM 17842(T) (96.7 %) and Paenibacillus zanthoxyli DSM 18202(T) (96.6 %). However, DNA-DNA hybridization values between strain S27(T) and the four type strains were 37.64 %, 23.12 %, 25.6 % and 34.99 %, respectively. Levels of 16S rRNA gene sequence similarity between strain S27(T) and the type strains of other recognized members of the genus Paenibacillus were below 96.5 %. The DNA G+C content of strain S27(T) was 46.0 mol%. The major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). The major isoprenoid quinone was MK-7. On the basis of its phenotypic characteristics and DNA-DNA hybridization results, strain S27(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sophorae sp. nov. is proposed. The type strain is S27(T) ( = CGMCC 1.10238(T)  = DSM 23020(T)).

Identification of Bacillus cereus genes specifically expressed during growth at low temperatures

The mechanisms involved in the ability of Bacillus cereus to multiply at low temperatures were investigated. It was assumed that many genes involved in cold acclimation would be upregulated at low temperatures. Recombinase-based in vivo expression technology (IVET) was adapted to the detection of the transient activation of B. cereus promoters during growth at 10 degrees C. Four independent screenings of a promoter library from type strain ATCC 14579 were performed, and 17 clones were isolated. They corresponded to 17 promoter regions that displayed reproducibly elevated expression at 10 degrees C relative to expression at 30 degrees C. This analysis revealed several genes that may be important for B. cereus to grow successfully under the restrictive conditions of cold habitats. Among them, a locus corresponding to open reading frames BC5402 to BC5398, harboring a lipase-encoding gene and a putative transcriptional regulator, was identified three times. While a mutation in the putative regulator-encoding gene did not cause any particular phenotype, a mutant deficient in the lipase-encoding gene showed reduced growth abilities at low temperatures compared with the parental strain. The mutant did not change its fatty acid profiles in the same way as the wild type when grown at 12 degrees C instead of 37 degrees C. This study demonstrates the feasibility of a promoter trap strategy for identifying cold-induced genes. It outlines a first picture of the different processes involved in B. cereus cold acclimation.

Paenibacillus sonchi sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Sonchus oleraceus

A nitrogen-fixing bacterium, designated strain X19-5(T), was isolated from rhizosphere soil of Sonchus oleraceus. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain X19-5(T) was a member of the genus Paenibacillus. Strain X19-5(T) showed the highest 16S rRNA gene sequence similarity (98.8 %) with Paenibacillus graminis RSA19(T) and below 97 % similarity with other recognized members of the genus. The level of DNA-DNA relatedness between strain X19-5(T) and P. graminis RSA19(T) was 45.7 %. The DNA G+C content of strain X19-5(T) was 46.8 mol%. The major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). On the basis of its phenotypic characteristics and the level of DNA-DNA hybridization, strain X19-5(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sonchi sp. nov. is proposed. The type strain is X19-5(T) (=CCBAU 83901(T)=LMG 24727(T)).

A selective chromogenic agar that distinguishes Bacillus anthracis from Bacillus cereus and Bacillus thuringiensis

A selective and differential plating medium, R & F anthracis chromogenic agar (ACA), has been developed for isolating and identifying presumptive colonies of Bacillus anthracis. ACA contains the chromogenic substrate 5-bromo-4-chloro-3-indoxyl-choline phosphate that upon hydrolysis yields teal (blue green) colonies indicating the presence of phosphatidylcholine-specific phospholipase C (PC-PLC) activity. Among seven Bacillus species tested on ACA, only members of the Bacillus cereus group (B. anthracis, B. cereus, and B. thuringiensis) produced teal colonies (PC-PLC positive) having cream rings. Examination of colony morphology in 18 pure culture strains of B. anthracis (15 ATCC strains plus AMES-1-RIID, ANR-1, and AMED-RIID), with one exception, required 48 h at 35 to 37 degrees C for significant color production, whereas only 24 h was required for B. cereus and B. thuringiensis. This differential rate of PC-PLC synthesis in B. anthracis (due to the truncated plcR gene and PlcR regulator in B. anthracis) allowed for the rapid differentiation on ACA of presumptive colonies of B. anthracis from B. cereus and B. thuringiensis in both pure and mixed cultures. Effective recovery of B. anthracis from a variety of matrices having both high (soil and sewage) and low microbial backgrounds (cloth, paper, and blood) spiked with B. anthracis ANR-1 spores suggests the probable utility of ACA plating for B. anthracis recovery in a diversity of applications.