Inorganic carbon and pH effect on growth and lipid productivity of Tetraselmis suecica and Chlorella sp (Chlorophyta) grown outdoors in bag photobioreactors

There has been considerable interest in cultivation of green microalgae (Chlorophyta) as a source of lipid that can alternatively be converted to biodiesel. However, almost all mass cultures of algae are carbon-limited. Therefore, to reach a high biomass and oil productivities, the ideal selected microalgae will most likely need a source of inorganic carbon. Here, growth and lipid productivities of Tetraselmis suecica CS-187 and Chlorella sp were tested under various ranges of pH and different sources of inorganic carbon (untreated flue gas from coal-fired power plant, pure industrial CO₂, pH-adjusted using HCl and sodium bicarbonate). Biomass and lipid productivities were highest at pH 7.5 (320?±?29.9 mg biomass L^?1 day^?1and 92?±?13.1 mg lipid L^?1 day^?1) and pH 7 (407?±?5.5 mg biomass L^?1 day^?1 and 99?±?17.2 mg lipid L^?1 day^?1) for T. suecica CS-187 and Chlorella sp, respectively. In general, biomass and lipid productivities were pH 7.5?>?pH 7?>?pH 8?>?pH 6.5 and pH 7?>?pH 7.5?=?pH 8?>?pH 6.5?>?pH 6?>?pH 5.5 for T. suecica CS-187 and Chlorella sp, respectively. The effect of various inorganic carbon on growth and productivities of T. suecica (regulated at pH?=?7.5) and Chlorella sp (regulated at pH?=?7) grown in bag photobioreactors was also examined outdoor at the International Power Hazelwood, Gippsland, Victoria, Australia. The highest biomass and lipid productivities of T. suecica (51.45?±?2.67 mg biomass L^?1 day^?1 and 14.8?±?2.46 mg lipid L^?1 day^?1) and Chlorella sp (60.00?±?2.4 mg biomass L^?1 day^?1 and 13.70?±?1.35 mg lipid L^?1 day^?1) were achieved when grown using CO₂ as inorganic carbon source. No significant differences were found between CO₂ and flue gas biomass and lipid productivities. While grown using CO₂ and flue gas, biomass productivities were 10, 13 and 18 %, and 7, 14 and 19 % higher than NaHCO₃, HCl and unregulated pH for T. suecica and Chlorella sp, respectively. Addition of inorganic carbon increased specific growth rate and lipid content but reduced biomass yield and cell weight of T. suecica. Addition of inorganic carbon increased yield but did not change specific growth rate, cell weight or content of the cell weight of Chlorella sp. Both strains showed significantly higher maximum quantum yield (F_v/F_m) when grown under optimum pH.     

Comparison of biomass production and total lipid content of freshwater green microalgae cultivated under various culture conditions

The growth and total lipid content of four green microalgae (Chlorella sp., Chlorella vulgaris CCAP211/11B, Botryococcus braunii FC124 and Scenedesmus obliquus R8) were investigated under different culture conditions. Among the various carbon sources tested, glucose produced the largest biomass or microalgae grown heterotrophically. It was found that 1 % (w/v) glucose was actively utilized by Chlorella sp., C. vulgaris CCAP211/11B and B. braunii FC124, whereas S. obliquus R8 preferred 2 % (w/v) glucose. No significant difference in biomass production was noted between heterotrophic and mixotrophic (heterotrophic with light illumination/exposure) growth conditions, however, less production was observed for autotrophic cultivation. Total lipid content in cells increased by approximately two-fold under mixotrophic cultivation with respect to heterotrophic and autotrophic cultivation. In addition, light intensity had an impact on microalgal growth and total lipid content. The highest total lipid content was observed at 100 μmol m^?2s^?1 for Chlorella sp. (22.5 %) and S. obliquus R8 (23.7 %) and 80 μmol m^?2s^?1 for C. vulgaris CCAP211/11B (20.1 %) and B. braunii FC124 (34.9 %).     

Bacillus zhanjiangensis sp. nov., isolated from an oyster in South China Sea

A novel Gram-stain-positive, motile, catalase- and oxidase-positive, endospore-forming, aerobic, rod-shaped bacterium, designated strain JSM 099021^T, was isolated from an oyster collected from Naozhou Island in the South China Sea. Growth occurred with 0?C15% (w/v) NaCl (optimum 2?C4%) and at pH 6.0?C10.0 (optimum pH 7.5) and at 10?C45°C (optimum 30?C35°C). meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. The predominant respiratory quinone was menaquinone 7 (MK-7) and the major polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The major cellular fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C15:0 and iso-C16:0. The genomic DNA G + C content was 39.5 mol%. A phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 099021^T belongs to the genus Bacillus, and was most closely related to the type strains of Bacillus halmapalus (sequence similarity 99.0%), Bacillus horikoshii (98.4%) and Bacillus cohnii (98.0%). The combination of phylogenetic analysis, DNA?CDNA hybridization, phenotypic characteristics and chemotaxonomic data supported the proposal that strain JSM 099021^T represents a new species of the genus Bacillus, for which the name Bacillus zhanjiangensis sp. nov. is proposed. The type strain was JSM 099021^T (=DSM 23010^T = KCTC 13713^T).     

Isolation and lipid degradation profile of Raoultella planticola strain 232-2 capable of efficiently catabolizing edible oils under acidic conditions

The lipids (fats and oils) degradation capabilities of soil microorganisms were investigated for possible application in treatment of lipids-contaminated wastewater. We isolated a strain of the bacterium Raoultella planticola strain 232-2 that is capable of efficiently catabolizing lipids under acidic conditions such as in grease traps in restaurants and food processing plants. The strain 232-2 efficiently catabolized a mixture (mixed lipids) of commercial vegetable oil, lard, and beef tallow (1:1:1, w/w/w) at 20–35 °C, pH 3–9, and 1,000–5,000 ppm lipid content. Highly effective degradation rate was observed at 35 °C and pH 4.0, and the 24-h degradation rate was 62.5?±?10.5 % for 3,000 ppm mixed lipids. The 24-h degradation rate for 3,000 ppm commercial vegetable oil, lard, beef tallow, mixed lipids, and oleic acid was 71.8 %, 58.7 %, 56.1 %, 55.3?±?8.5 %, and 91.9 % at pH 4 and 30 °C, respectively. R. planticola NBRC14939 (type strain) was also able to efficiently catabolize the lipids after repeated subculturing. The composition of the culture medium strongly influenced the degradation efficiency, with yeast extract supporting more complete dissimilation than BactoPeptone or beef extract. The acid tolerance of strain 232-2 is proposed to result from neutralization of the culture medium by urease-mediated decomposition of urea to NH₃. The rate of lipids degradation increased with the rates of neutralization and cell growth. Efficient lipids degradation using strain 232-2 has been achieved in the batch treatment of a restaurant wastewater.     

Thalassococcus lentus sp. nov., an alphaproteobacterium isolated from seawater of a seaweed farm

A Gram-negative, non-motile and rod- or ovoid-shaped bacterial strain, designated YCS-24^T, was isolated from seawater of a seaweed farm in the South Sea, South Korea. Strain YCS-24^T grew optimally at 25–28 °C, at pH 7.0–7.5 and in the presence of 2 % (w/v) NaCl. Strain YCS-24^T exhibited the highest 16S rRNA gene sequence similarity values of 97.5 and 97.1 % to the type strains of Thalassobius maritimus and Thalassococcus halodurans, respectively. The neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain YCS-24^T clustered with the type strain of T. halodurans. The DNA G+C content of strain YCS-24^T was 58.0 mol% and its DNA–DNA relatedness values with T. halodurans JCM 13833^T and T. maritimus GSW-M6^T were 17 ± 6.2 and 23 ± 9.2 %, respectively. The predominant ubiquinone found in strain YCS-24^T was Q-10 and the predominant fatty acid of strain YCS-24^T was C_18:1 ω7c. The major polar lipids of strain YCS-24^T were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, demonstrated that strain YCS-24^T is distinguished from T. halodurans. On the basis of the data presented, strain YCS-24^T (= KCTC 32084^T = CCUG 62791^T) represents a novel species of the genus Thalassococcus, for which the name Thalassococcus lentus sp. nov. is proposed.     

Halorubrum salinum sp. nov., isolated from a marine solar saltern

The halophilic archaeal strain GX71^T was isolated from the Gangxi marine solar saltern near the Weihai city of Shandong Province, China. Cells of the strain were pleomorphic and lysed in distilled water, stained Gram-negative and formed red-pigmented colonies. Strain GX71^T was able to grow at 25–45 °C (optimum 30 °C), in the presence of 1.7–4.8 M NaCl (optimum 2.6 M NaCl), with 0.005–0.7 M MgCl₂ (optimum 0.05 M MgCl₂) and at pH 5.5–9.5 (optimum pH 7.0–7.5). Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 10 % (w/v). The major polar lipids of the strain were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, one major glycolipid chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-3) and an unidentified lipid was also detected. The 16S rRNA gene sequence of strain GX71^T showed 94.0–97.0 % similarity to members of the genus Halorubrum of the family Halobacteriaceae. The rpoB′ gene sequence of strain GX71^T was 87.3–93.4 % similarity to current members of the genus Halorubrum. The DNA G+C content of GX71^T was 67.1 mol%. Strain GX71^T showed low DNA–DNA relatedness with Halorubrum lipolyticum CGMCC 1.5332^T, Halorubrum saccharovorum CGMCC 1.2147^T, Halorubrum kocurii CGMCC 1.7018^T and Halorubrum arcis CGMCC 1.5343^T, the most closely related members of the genus Halorubrum. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain GX71^T represents a novel species of the genus Halorubrum, for which the name Halorubrum salinum sp. nov. is proposed. The type strain is GX71^T (= CGMCC 1.10458^T = JCM 17093^T).     

Natronorubrum texcoconense sp. nov., a haloalkaliphilic archaeon isolated from soil of the former lake Texcoco (Mexico)

A new haloalkaliphilic archaeon, strain B4^T, was isolated from the former lake Texcoco in Mexico. The cells were Gram-negative, pleomorphic-shaped, pink to red pigmented and aerobic. Strain B4^T required at least 2.5 M NaCl for growth, with optimum growth at 3.4 M NaCl. It was able to grow over a pH range of 7.5–10.0 and temperature of 25–50 °C, with optimal growth at pH 9 and 37 °C. Cells are lysed in hypotonic treatment with less than 1.3 M NaCl. The major polar lipids of strain B4^T were phosphatidylglycerol and methyl-phosphatidylglycerophosphate. Phospholipids were detected, but not glycolipids. The nucleotide sequence of the 16S rRNA gene revealed that the strain B4^T was phylogenetically related to members of the genus Natronorubrum. Sequence similarity with Natronorubrum tibetense was 96.28 %, with Natronorubrum sulfidifaciens 95.06 % and Natronorubrum sediminis 94.98 %. The G+C content of the DNA was 63.3 mol%. The name of Natronorubrum texcoconense sp. nov. is proposed. The type strain is B4^T (=CECT 8067^T = JCM 17497^T).     

Pelagicola litorisediminis sp. nov., a novel alphaproteobacterium isolated from tidal flat sediment

A Gram-negative, aerobic, non-motile and rod-shaped or ovoid bacterial strain, designated D1-W8^T, was isolated from a tidal flat on the South Sea in South Korea. Strain D1-W8^T was found to grow optimally at 25 °C, at pH 7.0–8.0 and in the presence of 2.0–3.0 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain D1-W8^T clustered with the type strain of Pelagicola litoralis showing 97.1 % sequence identity. 16S rRNA gene sequences of the type strains of other species exhibited lower similarity values. Strain D1-W8^T was determined to contain Q-10 as the predominant ubiquinone and C_18:1 ω7c as the predominant fatty acid. The major polar lipids of strain D1-W8^T were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain D1-W8^T was determined to be 57.9 mol% and its DNA–DNA relatedness value with the type strain of P. litoralis was 17 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain D1-W8^T is separate from P. litoralis. On the basis of the data presented, strain D1-W8^T is considered to represent a novel species of the genus Pelagicola, for which the name Pelagicola litorisediminis sp. nov. is proposed. The type strain is D1-W8^T (= KCTC 32327^T = CECT 8287^T).     

Detection of intracellular neutral lipid content in the marine microalgae Prorocentrum micans and Phaeodactylum tricornutum using Nile red and BODIPY 505/515

Diatoms and dinoflagellates not only have extensive distribution and a huge biomass in marine ecosystems, but also have high lipid accumulation in nature or after physiological and genetic modification, which indicates that these organisms may be optimal candidate algal strains for biodiesel production. In this study, we determined the content of intracellular neutral lipids (triacylglycerol [TAG]) in the dinoflagellate Prorocentrum micans and in the diatom Phaeodactylum tricornutum using NR and BODIPY 505/515 staining. The freshwater green alga Scenedesmus obliquus was used as a control. Optimum concentrations of 1.000 and 1.500 μg mL^?1 were determined for neutral lipid Nile red (NR) staining in P. micans and P. tricornutum. Unlike NR staining, the optimal concentrations of BODIPY 505/515 staining in P. micans and P. tricornutum were lower, at 0.100 and 0.075 μg mL^?1, respectively. High correlation coefficients of R ²?=?0.990 and R ²?=?0.989 were obtained for P. micans and P. tricornutum intracellular neutral lipid content and the relative fluorescence intensity with NR staining, while the reference alga, S. obliquus, had a relatively low correlation coefficient of R ²?=?0.908 when stained with NR. The neutral lipid content determined by thin-layer chromatography-flame ionization detector matched the analytical data from fluorescence measurements. These results indicated that NR and BODIPY 505/515 staining can be used as an excellent high-throughput approach to screen marine diatoms and dinoflagellates.     

Effect of high ferric ion concentrations on total lipids and lipid characteristics of Tetraselmis subcordiformis,Nannochloropsis oculata and Pavlova viridis

Microalgae as sources for biodiesel production have been widely investigated. Microalgae biomass, lipid content and fatty acid profiles of microalgae are limiting factors for the cost-effective production of biodiesel. In this paper, the effects of high ferric ion concentrations on three species of microalgae (Tetraselmis subcordiformis, Nannochloropsis oculata and Pavlova viridis) were studied. The microalgae were cultured in different concentrations (1.2?×?10^?2, 1.2?×?10^?1, 1.2 and 12 mmol L^?1) of ferric ion. The growth, lipid content and fatty acid profiles of the three microalgae were analysed. When algae were cultured in 1.2 mmol L^?1 ferric ion for 10 days, the final cell density and specific growth rates of T. subcordiformis, N. oculata and P. viridis decreased significantly (p?<?0.05), and the total lipid contents of the microalgae, 33.72, 37.34 and 29.48 % (dry mass) in T. subcordiformis, N. oculata and P. viridis, respectively, were higher than those at other concentrations. The neutral lipid/total lipid ratios of the three microalgae species increased with increasing ferric ion concentration. Neutral lipids accounted for 50.75, 48.37 and 46.59 % of the total lipid in T. subcordiformis, N. oculata and P. viridis, respectively, when cultured in 12 mmol L^?1 ferric ion. The proportions of saturated fatty acids in all three species cultured in 12 mmol L^?1 ferric ion were significantly higher than those cultured in lower ferric ion concentrations. An optimum ferric ion concentration can improve the properties of T. subcordiformis, N. oculata and P. viridis as sources for biodiesel.     

Ornithinibacillus heyuanensis sp. nov., isolated from South China

A novel Gram-stain-positive, motile, hemolytic, endospore-forming and rod-shaped bacterium was isolated and designated as strain GIESS003^T. The strain grew optimally at 35 °C, at pH 7.0–7.5, and with 3.0–3.5 % (w/v) NaCl. The 16S rRNA gene sequence analysis indicated that strain GIESS003^T was associated with the genus Ornithinibacillus and was most closely related to the type strain of Ornithinibacillus contaminans (96.5 % similarity). The major cellular fatty acids were iso-C_15:0 and anteiso-C_15:0. The polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The major respiratory quinone was menaquinone-7. Strain GIESS003^T contained a peptidoglycan of type A4β l-Orn-d-Asp. The G+C content of genomic DNA was 40.1 mol%. On the basis of polyphasic evidence from this study, a new species of the genus Ornithinibacillus, Ornithinibacillus heyuanensis sp. nov., is proposed, with strain GIESS003^T (=KCTC 33159^T=CCTCC 2013106^T) as the type strain.     

Bacillus hunanensis sp. nov., a slightly halophilic bacterium isolated from non-saline forest soil

A novel Gram-stain-positive, slightly halophilic, catalase- and oxidase-positive, endospore-forming, motile, aerobic, rod-shaped bacterium, designated strain JSM 081003^T, was isolated from non-saline forest soil in Hunan Province, China. Growth occurred with 0.5?C15% (w/v) NaCl (optimum 2?C4%) at pH 6.5?C10.5 (optimum pH 7.5?C8.5) and at 5?C40°C (optimum 30°C). meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. The major cellular fatty acids were iso-C15:0, anteiso-C15:0 and iso-C14:0. Strain JSM 081003^T contained MK-7 as the predominant respiratory quinone, and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol as the major polar lipids. The genomic DNA G + C content of strain JSM 081003^T was 40.9 mol%. A phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain JSM 081003^T should be assigned to the genus Bacillus, and was related most closely to the type strains of Bacillus lehensis (sequence similarity 99.6%), Bacillus oshimensis (99.4%) and Bacillus patagoniensis (96.6%); lower than 96.0% sequence similarity was observed with other Bacillus species. The combination of phylogenetic analysis, DNA?CDNA relatedness values, phenotypic characteristics and chemotaxonomic data supports the view that strain JSM 081003^T represents a new species of the genus Bacillus, for which the name Bacillus hunanensis sp. nov. is proposed. The type strain is JSM 081003^T (= DSM 23008^T = KCTC 13711^T).     

Paracoccus pacificus sp. nov., isolated from the Western Pacific Ocean

A Gram-stain negative, short rod-shaped, non-motile, catalase- and oxidase-positive, aerobic bacterium, designated F14^T, was isolated from the Western Pacific Ocean. Phylogenetic and phenotypic properties of the organism supported that it belongs to the genus Paracoccus. The levels of 16S rRNA gene sequences similarity between strain F14^T and other type strains of recognized members of the genus Paracoccus were 93.6–96.5 %. Growth of strain F14^T was observed at 4–40 °C (optimum, 28–30 °C), pH 6.0–10.0 (optimum, pH 7.0–8.0) and in the presence of 0–7 % (w/v) NaCl (optimum, 1–2 %). The major cellular fatty acid was summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c). The major respiratory quinone was ubiquinone-10. The polar lipid pattern indicated the presence of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and three unknown lipids. The DNA G+C content was 61.4 mol%. On the basis of polyphasic characterization, strain F14^T represents a novel species, for which the name Paracoccus pacificus sp. nov. is proposed. The type strain is F14^T (=CGMCC 1.12755^T=LMG 28106^T=MCCC 1A09947^T).     

Roseovarius gaetbuli sp. nov., a novel alphaproteobacterium isolated from a tidal flat sediment

A Gram-negative, aerobic, non-motile and ovoid or rod-shaped bacterial strain, designated YM-20^T, was isolated from a tidal flat of the Yellow Sea in South Korea. Strain YM-20^T was found to grow optimally at 30 °C, at pH 7.0–8.0 and in the presence of 2.0–3.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain YM-20^T clustered consistently with the type strains of ‘Roseovarius marisflavi’ and Roseovarius lutimaris, with which it exhibited 16S rRNA gene sequence similarities of 99.86 and 98.71 %, respectively. Strain YM-20^T was found to contain Q-10 as the predominant ubiquinone and C_18:1 ω7c as the predominant fatty acid. The major polar lipids of strain YM-20^T were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain YM-20^T was determined to be 60.9 mol% and its DNA–DNA relatedness values with the type strains of ‘R. marisflavi’, R. lutimaris and Pelagicola litorisediminis were 53 ± 7.1, 22 ± 5.5 and 13 ± 4.7  %, respectively. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain YM-20^T is separated from ‘R. marisflavi’, R. lutimaris, the other Roseovarius species and P. litorisediminis. On the basis of the data presented, strain YM-20^T is considered to represent a novel species of the genus Roseovarius, for which the name Roseovarius gaetbuli sp. nov. is proposed. The type strain is YM-20^T (= KCTC 32428^T = CECT 8370^T).     

Clostridium swellfunianum sp. nov., a novel anaerobic bacterium isolated from the pit mud of Chinese Luzhou-flavor liquor production

A novel Gram-positive, strictly anaerobic, spore-forming, rod-shaped bacterium, designated strain S11-3-10^T, was isolated from the pit mud used for Chinese Luzhou-flavor liquor production. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the strain formed a monophyletic clade with the closely related type strains of Clostridium cluster I and was most closely related to Clostridium amylolyticum JCM 14823^T (94.38 %). The temperature, pH, and NaCl range for growth was determined to be 20–45 °C (optimum 37 °C), 4.0–10.0 (optimum pH 7.3), and 0–3.0 % (w/v), respectively. The strain was able to tolerate up to 7.5 % (v/v) ethanol. Yeast extract or peptone was found to be required for growth. Acids were found to be produced from glucose, mannose and trehalose. The major end products from glucose fermentation were identified as ethanol, acetate and hydrogen. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and unidentified phospholipids and polar lipids. The major fatty acids (>5 %) were identified as iso-C_15:0, C_16:0, C_16:0 dma, C_14:0, anteiso-C_15:0 and iso-C_13:0. No respiratory quinone was detected. The diamino acid in the cell wall peptidoglycan was identified as meso-diaminopimelic acid and the whole-cell sugars were found to include galactose and glucose as major components. The DNA G+C content was determined to be 36.4 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic evidence, the isolate is considered to represent a novel species of the genus Clostridium for which the name Clostridium swellfunianum sp. nov. is proposed. The type strain is S11-3-10^T (=DSM 27788^T = JCM 19606^T = CICC 10730^T).     

Bacillus borbori sp. Nov., Isolated From an Electrochemically Active Biofilm

A Gram-positive, facultative anaerobic, motile, endospore-forming rod strain, designated DX-4^T, was isolated from an electrochemically active biofilm. Growth occurred at 30–65 °C (optimum 55 °C), at pH 6.0–8.5 (optimum pH 7.0–7.5) and with <6 % (w/v) NaCl. Cells were catalase- and oxidase-positive. The main respiratory quinone was MK-7, the predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside, and unidentified aminophospholipid, the DNA G+C content was 38.6 mol% and the major fatty acids (>5 %) were iso-C_15:0 (38.9 %), iso-C_17:0 (30.5 %), iso-C_16:0 (5.6 %), and anteiso-C_17:0 (5.2 %). The phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain DX-4^T is a member of the genus Bacillus. The results of phenotypic, chemotaxonomic, and genotypic analyses clearly indicated that strain DX-4^T represents a novel species, for which the name Bacillus borbori sp. nov. is proposed. The type strain is DX-4^T (= CCTCC AB2012196^T = KCTC 33103^T).     

Characterization of the triacylglycerol profile in marine diatoms by ultra performance liquid chromatography coupled with electrospray ionization–quadrupole time-of-flight mass spectrometry

Diatoms are considered to have great potential as new biofuel sources because they can effectively accumulate triacylglycerols (TAGs). Detailed structure information of TAG in diatoms is much needed not only for the assessment of biofuel quality such as fatty acid chain length and unsaturation degree but also for the tracing of biosynthetic precursors because the biosynthesis of TAG is typically completed by utilizing the diacylglycerol acyltransferase in the cytoplasm. In this report, a comprehensive characterization of TAGs in marine diatoms was performed using ultra performance liquid chromatography–electrospray ionization–quadrupole time-of-flight mass spectrometry. Many types of major TAGs were identified for the first time in these diatoms: 12 TAGs in Chaetoceros debilis, 9 TAGs in Phaeodactylum tricornutum Bohlin, 16 TAGs in Nitzschia closterium f. minutissima, 16 TAGs in Thalassiosira weissflogii, 13 TAGs in Thalassiosira sp., 16 TAGs in Stephanodiscus asteaea and 7 TAGs in Skeletonema costatum. Semi-quantification of TAGs in these diatoms was also carried out, and it was found that the contents of individual TAGs ranged from 0.5?±?0.1 to 217.9?±?8.1 nmol mg^?1 total lipids. In addition, the total lipid contents in diatoms ranged from 143.6?±?16.3 to 201.1?±?16.3 mg g^?1 dry microalgae and the total TAG contents ranged from 36.8?±?9.5 to 793.2?±?54.4 nmol mg^?1 total lipids. By comparative analysis of the compositions and concentrations of major TAGs in the seven algal strains, N. closterium f. minutissima with high abundance of TAGs containing the most monounsaturated fatty acids (mainly palmitoleic acid) was considered as one of the most promising diatom strains for microalgal biofuel production. Additionally, based on the information of sn-2 fatty acid obtained (mainly C16 in the sn-2 position), we propose the hypothesis that TAGs in diatoms are mainly derived from lipids in chloroplasts through the prokaryotic biosynthesis pathway, including monogalactosyldiacylglycerol and digalactosyldiacylglycerol.     

Marinobacter persicus sp. nov., a moderately halophilic bacterium from a saline lake in Iran

A Gram-negative, non-endospore-forming, rod shaped, strictly aerobic, moderately halophilic bacterium, designated strain M9B^T, was isolated from the hypersaline lake Aran-Bidgol in Iran. Cells of strain M9B^T were found to be motile and produce colonies with an orange-yellow pigment. Growth was determined to occur between 5 and 20 % (w/v) NaCl and the isolate grew optimally at 7.5–10 % (v/w) NaCl. The optimum pH and temperature for growth of the strain were determined to be pH 7.0 and 35 °C, respectively, while it was able to grow over pH and temperature ranges of 6–8 and 25–45 °C, respectively. Phylogenetic analysis based on the comparison of 16S rRNA gene sequences revealed that strain M9B^T is a member of the genus Marinobacter. The closest relative to this strain was found to be Marinobacter hydrocarbonoclasticus MBIC 1303^T with a similarity level of 97.7 %. DNA–DNA hybridization between the novel isolate and this phylogenetically related species was 13 ± 2 %. The major cellular fatty acids of the isolate were identified as C_16:0, C_19:1 ω6c, C_18:1 ω9c and C_16:1 ω9c. The polar lipid pattern of strain M9B^T was determined to consist of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine and three phospholipids. Ubiquinone 9 (Q-9) was the only lipoquinone detected. The G+C content of the genomic DNA of this strain was determined to be 58.6 mol%. Phenotypic characteristics, phylogenetic analysis and DNA–DNA relatedness data suggest that this strain represents a novel species of the genus Marinobacter, for which the name Marinobacter persicus sp. nov. is proposed. The type strain of Marinobacter persicus is strain M9B^T (=IBRC-M 10445^T = CCM 7970^T = CECT 7991^T = KCTC 23561^T).     

Paludibacter jiangxiensis sp. nov., a strictly anaerobic,propionate-producing bacterium isolated from rice paddy field

A mesophilic, obligately anaerobic, propionate-producing fermentative bacterium, designated strain NM7^T, was isolated from rural rice paddy field. Cells of strain NM7^T are Gram-negative, non-motile, non-spore-forming, short rods, and negative for catalase. The strain grew optimally at 37 °C (the range for growth 15–40 °C) and pH 7.0 (pH 5.0–7.5). The strain could grow fermentatively on various sugars, including arabinose, xylose, fructose, galactose, glucose, mannose, cellobiose, lactose, maltose, sucrose, pectin and starch. The main end products of glucose fermentation were acetate and propionate. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe(III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of genomic DNA was 42.8 mol%. The major cellular fatty acids were C_15:0, anteiso-C_15:0, C_16:0, and C_17:0. The most abundant polar lipid of strain NM7^T was phosphatidylethanolamine. 16S rRNA gene sequence analysis revealed that it belongs to the family Porphyromonadaceae of the phylum Bacteroidetes. The closest recognized species was Paludibacter propionicigenes (91.4 % similarity in 16S rRNA gene sequence). A novel species, Paludibacter jiangxiensis sp. nov., is proposed to accommodate strain NM7^T (=JCM 17480^T = CGMCC 1.5150^T = KCTC 5844^T).     

At high temperature lipid production in Ettlia oleoabundans occurs before nitrate depletion

Temperature and light intensity effects on biomass and lipid production were investigated in Ettlia oleoabundans to better understand some fundamental properties of this potentially useful but poorly studied microalgal species. E. oleoabundans entered dormant state at 5 °C, showed growth at 10 °C, and when exposed to light at 70 μmol photons per square meter per second at 10 °C, cells reached a biomass concentration of >2.0 g?L^?1 with fatty acid methyl esters of 11.5 mg?L^?1. Highest biomass productivity was at 15 °C and 25 °C regardless of light intensity, and accumulation of intracellular lipids was stimulated by nitrate depletion under these conditions. Although growth was inhibited at 35 °C, at 130 μmol photons per square meter per second lipid content reached 10.37 mg?L^?1 with fatty acid content more favorable to biodiesel dominating; this occurred without nitrate depletion. In a two-phase temperature shift experiment at two nitrate levels, cells were shifted after 21 days at 15 °C to 35 °C for 8 days. Although after the shift growth continued, lipid productivity per cell was less than that in the 35 °C cultures, again without nitrate depletion. This study showed that E. oleoabundans grows well at low temperature and light intensity, and high temperature can be a useful trigger for lipid accumulation independent of nitrate depletion. This will prove useful for improving our knowledge about lipid production in this and other oleaginous algae for modifying yield and quality of algal lipids being considered for biodiesel production.