Optimization of Extraction Parameters and Characterization of Tunisian Date Extract: A Scientific Approach Toward Their Utilization.

The response surface methodology (RSM) was used in order to select the extraction conditions of extract from Kentichi date powder; a by-product of the date-processing process. Powder/solvent ratio, extraction temperature, and extraction time all had an impact on sugar yield, and these model factors have quadratic effects influencing sugar yield. Optimal extraction was obtained with 300 g/L powder/solvent ratio, 32.7 °C extraction temperature, and 2.1 h extraction time. Under these conditions, Kentichi date powder's (KDP) sugar yield was 77.1%, which was close to the predicted value of the model (80.50%). The results of Kentichi date powder extract (KDPE) showed that the total sugar content is 160.09 g/L. However, the protein content is 10.31 g/L with a majority of the essential amino acids (essentially glutamic acid (28.39 mg/L) and aspartic acid (9.65 mg/L)). The determination of antioxidant activity of KDPE showed a high activity (DPPH IC50 = 4.8 mg/mL, ABTS IC50 = 3 mg/mL, FRAP = 4.70 µmol AAE/mL and, TAA = 18.04 µmol Fe(II)/mL). The results show also that the freeze-drying technique has a lot of potential for producing powder from KDPE with many desirable properties. The findings indicate that KDPE with a high nutritional value could be used as a component for the formulation of functional foods. Supplementary Information: The online version contains supplementary material available at 10.1007/s12355-022-01223-2.

Occurrence of Staphylococcus spp. and investigation of fecal and animal viral contaminations in livestock, river water, and sewage from Tunisia and Romania.

The objective of this study was to determine the occurrence of Staphylococcus spp., Escherichia coli, somatic coliphages, F-specific RNA bacteriophages, hepatitis E virus (HEV), and bovine enterovirus (BEV) in fecal and water samples. The occurrence of Staphylococcus spp. was investigated in treated wastewater samples collected from slaughterhouse of Tunisia. Results showed that Staphylococcus spp. were detected in the totality of collected samples with an average mean of 5.44 Log10 (CFU/100 ml). Regarding fecal indicator bacteria, E. coli was detected in the totality of water samples and was more abundant in Tunisian samples than in samples collected from Romania (P < 0.05). Concerning somatic coliphages and F-specific RNA bacteriophages used as viral indicators, they were detected in all raw and treated wastewaters. Bovine enterovirus (BEV) was detected in 20.1% and 28% of bovine stool samples collected from Tunisia and Romania, respectively. BEV was also detected in 60% of porcine stool samples from Romania. BEV was absent in all treated sewage samples. HEV was detected in raw sewage and bovine fecal sample from Romania with low occurrence and none sample from Tunisia was positive. This study may give us an insight into the monitoring of water quality in Tunisia and Romania.

Valorization of residual soft drinks by baker's yeast production and insight for dairy wastewater whey incorporation.

Residuals are responsible for the polluting load increase of soft drink industry wastewater due to their high sugar contents. The present work proposes an upstream segregation of residuals to be biologically treated by the bioconversion of their carbohydrates content into baker's yeast biomass. Carbonated soft drinks (CSD) and nectars and juices (NJ) ranges were considered. Different incorporation ratios of NJ in the CSD (0-75%) have been investigated for balanced growth medium. Despite the nitrogen deficiency of media, results showed that NJ incorporation promoted the microbial growth. Media containing more than 50% of NJ exhibited ∼25% sugar-biomass conversion rates. The chemical oxygen demand (COD) of the media exceeded 70% at the end of fermentation. Moreover, valuable components were recovered by yeast production. Nutrient consumption rates varied from 65.4% for sugar and calcium content to in excess of 99% for protein and other minerals. In order to investigate an available and low-cost source of nitrogen for yeast production, partial substitution of the soft drink growth medium by bactofugate whey was evaluated. The soft drink-whey mixture medium fermentation resulted in 63% COD removal rate after 28 h. Meanwhile, the biomass production yield revealed an improvement of about 25% compared to the balanced soft drink medium (NJ50).

Obligate sugar oxidation in Mesotoga spp., phylum Thermotogae, in the presence of either elemental sulfur or hydrogenotrophic sulfate-reducers as electron acceptor.

Mesotoga prima strain PhosAc3 is a mesophilic representative of the phylum Thermotogae comprising only fermentative bacteria so far. We show that while unable to ferment glucose, this bacterium is able to couple its oxidation to reduction of elemental sulfur. We demonstrate furthermore that M. prima strain PhosAc3 as well as M. prima strain MesG1 and Mesotoga infera are able to grow in syntrophic association with sulfate-reducing bacteria (SRB) acting as hydrogen scavengers through interspecies hydrogen transfer. Hydrogen production was higher in M. prima strain PhosAc3 cells co-cultured with SRB than in cells cultured alone in the presence of elemental sulfur. We propose that the efficient sugar-oxidizing metabolism by M. prima strain PhosAc3 in syntrophic association with a hydrogenotrophic sulfate-reducing bacterium can be extrapolated to all members of the Mesotoga genus. Genome comparison of Thermotogae members suggests that the metabolic difference between Mesotoga and Thermotoga species (sugar oxidation versus fermentation) is mainly due to the absence of the bifurcating [FeFe]-hydrogenase in the former. Such an obligate oxidative process for using sugars, unusual within prokaryotes, is the first reported within the Thermotogae. It is hypothesized to be of primary ecological importance for growth of Mesotoga spp. in the environments that they inhabit.

Reduction of adsorbed dyes content in the discharged sludge coming from an industrial textile wastewater treatment plant using aerobic activated sludge process.

Dye mass balance study at full-scale industrial textile wastewater (ITW) treatment plant showed that 1.5 ton of excess waste sludge, containing 304.5 Kg of dyes, are daily produced and discharged in landfills. Therefore, this by-product of activated sludge process (ASP) presents a serious environmental problem. In this work, a laboratory and pilot scale investigations were carried out to optimize aerobic biodegradation efficiency to reduce the amount of residual adsorbed dye that will be found in the waste sludge. The resistance of acclimated biomass to the toxicity of ITW was studied in 2.5 L batch reactors using different dye to biomass (D/B) ratios of 0.102, 0.25 and 0.72 g CODS/g VSS. Results of respirometric analyses showed that acclimated activated sludge (AS) biomass is able to treat ITW at high D/B ratio of 0.72 g CODS/g VSS. Moreover, biodegradation kinetic study using Monod law showed that COD and color removal were better for the highest D/B ratio. The half saturation coefficient of heterotrophs for indigo dye (KSind) of 20.01 g/m3 showed high affinity between biomass and dye molecules. Optimization of the process at pilot-scale with different hydraulic retention time (HRT) of 2-5 days, and different sludge recycling rates (SRR) of 220-680 m3/d, showed that high HRT of 5 days and a SRR of 0.22 allowed the best dye biodegradation efficiency (95%). Application of the best conditions at full-scale reduced significantly (89%) the amount of the discharged dyes from 304.5 Kg/d to 33 Kg/d. Results were numerically validated using a mathematical model based on the activated sludge model 1 (ASM1).

Novel approach for the use of dairy industry wastes for bacterial growth media production.

This work proposes a novel approach for the reuse and the recovery of dairy wastes valuable components. Thermal coagulation was performed for dairy effluents and the main responsible fraction for the organic matter content (protein and fat) was separated. Dairy curds were prepared for the formulation of bacterial growth media. Protein, sugar, fat and fatty acids contents have been assessed. Samples treated at 100 °C exhibited marked improvement in terms of protein (25-50%) recovery compared to those treated at 80 °C. Fatty acid analysis revealed the presence of unsaturated fatty acids (mainly oleic acid) that are essential to promote Lactobacillus growth. Previously isolated and identified bacterial strains from dairy wastes (Lactobacillus paracasei, Lactobacillus plantarum, Lactococcus lactis and Lactobacillus brevis) were investigated for their ability to grow on the formulated media. All the tested lactic acid bacteria exhibited greater bacterial growth on the formulated media supplemented with glucose only or with both glucose and yeast extract compared to the control media. By reference to the commercial growth medium, the productivity ratio of the supplemented bactofugate (B) and decreaming (D) formulated media exceeded 0.6 for L. paracasei culture. Whereas, the productivity ratio of the supplemented B medium was greater than 1 compared to the control medium for all the tested strains. As for the supplemented D medium, its productivity ratio was greater than 1 compared to the control medium for both L. paracasei and L. plantarum strains.

Benchmarking laboratory-scale pomegranate vinegar against commercial wine vinegars: antioxidant activity and chemical composition.

BACKGROUND: There is growing interest in the beneficial health effects of certain fruits, such as pomegranate, and their by-products, like vinegar. Vinegars contain antioxidant compounds such as polyphenols, which can scavenge free radicals in the body. In this study, the antioxidant properties (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid and 2,2-diphenyl-1-picrylhydrazyl scavenging capacities) and global polyphenolic composition of a new functional product, namely a pomegranate vinegar produced in the laboratory from the Gabsi variety, were evaluated and compared with those of commercial wine vinegars (Sherry and Rioja red wine Spanish vinegars). The evolution of the polyphenolic and volatile compositions during production of the pomegranate vinegar was also studied. RESULTS: The results indicate that pomegranate contained a relatively stable total phenolic content that is suitable for the elaboration of vinegar and that this product had an antioxidant capacity comparable to, or even better than, that observed for aged wine vinegars. Regarding the volatiles profile, a high proportion of esters (close to 50%), in relation to alcohols and fatty acids, was observed for pomegranate vinegar, and this is consistent with the high red fruits character identified by sensory analysis. CONCLUSION: Pomegranate vinegar produced in the laboratory has an antioxidant activity and a global phenolic content similar to those of red wine vinegars and higher than most of the white wine vinegars studied. The pomegranate vinegar retained the red fruit sensory character of pomegranate fruit. © 2018 Society of Chemical Industry.

Bioprocess development and preservation of functional food from tomato seed isolate fermented by kefir culture mixture.

The aim of this work was to explore the use of protein isolate from tomato seed enriched with the sucrose and the ascorbic acid as a medium for the growth of kefir mixture culture to develop a new non-dairy functional food. Unstructured mathematical and logistic models were proposed to describe cell growth, kefiran production, nutriment consumption and antioxidant activity. It was found that the maximal cell mass in the culture reached 8.38 g L-1 after 24 h of fermentation. A significant amount of kefiran was also produced (0.65 g L-1). The kefir culture growth significantly decreased protein content and enhanced the antioxidant activity during varied fermentation through the production of bio active peptides. After 24 h of fermentation, IC50 value for protein isolate was estimated to be about 10.48 µg mL-1. The proposed models adequately described the changes during fermentation and as observed as a promising approach for the formulation of tomato seed-based functional foods. The preservation of the isolate was also investigated through a spray-drying process. The effect of spray-drying on the viability of lactic acid bacteria and stability of protein content and the antioxidant activity of the powder was also carried out. Results showed that the spray-drying method has great potential for the synthesis of powder from the fermented isolate that are rich in desirable properties. However, it was appropriate to preserve the powder for 10 days at 37 °C for the preservation of protein functionality.

Anti-Acanthamoeba activity of Tunisian Thymus capitatus essential oil and organic extracts.

Acanthamoeba species are free-living amoebae widely distributed in the environment and which cause serious human infections. The treatment of Acanthamoeba infections is always very difficult and not constantly effective. More efficient drugs against Acanthamoeba must be developed and medicinal plants can be useful in this case. Our research focused on the examination of the anti-Acanthamoeba activity of the essential oil and the ethanolic-aqueous extract from Thymus capitatus L. The essential oil showed best activity with an IC50 of 2.73 µg/ml. The conducted Bio-guided fractionation of thyme extract result to the identification of two active compounds against the trophozoite stage of Acanthamoeba: thymol and 2,3-dihydroxy-p-cymene. The results have clearly shown that the investigated products may be successfully used against Acanthamoeba infections. These molecules that are found in plants may be an alternative for the development of new drugs.

Advanced oxidation process and biological treatments for table olive processing wastewaters: constraints and a novel approach to integrated recycling process: a review.

Table olive processing wastewaters constitute a dangerous environmental problem in the Mediterranean countries because of their large volumes, high organic matter and salt concentration. The quantity and the characteristics of wastewaters produced, and thus, their environmental impact, varied depending on the season, varieties, soil and process employed. Several chemicals, biological and combined technologies have proven effective at bringing down organic pollution and toxicity of these effluents. Advanced oxidation processes have recognized as highly efficient treatments for the degradation of organic matter. Nonetheless, complete mineralization is generally expensive without salt removal. Biological processes are the most environmentally compatible and least-expensive treatment methods, but these operations do not always provide satisfactory results. This article surveys the current available technologies and suggests an effective, cheaper alternative for the recycling and the valorization of green table olives wastewaters.

Valorization of functional properties of extract and powder of olive leaves in raw and cooked minced beef meat.

BACKGROUND: Olive leaves (OL), available in huge amounts from pruning, are known to be a useful source of biologically active compounds. This study investigated the potential application of OL as a supplement to minced beef meat in order to develop a functional product. The effect of OL extract or powder (100 and 150 µg phenols g-1 meat) on the quality and stability of raw and cooked meat during refrigerated storage was examined. RESULTS: Microwave drying at 600 W gave OL with the highest antioxidant quality (evaluated by TEAC/[phenols] (mg mg-1 ) and DPPH/[phenols] (mg mg-1 )) compared with other methods. OL showed an ability to inhibit (P < 0.05) lipid oxidation (TBARS values (mg MDA kg-1 ) were reduced by 25-65%) and myoglobin oxidation (metmyoglobin production was 43-65% in control samples and 14-35% in treated samples). OL also improved the technological quality of the meat, decreasing (P < 0.05) storage loss (%) and defrosting loss (%) without affecting cooking loss (%) and Napole yield (%). Sensory properties were not modified by the added ingredient at the tested levels (P < 0.05). CONCLUSION: OL (extract or powder) may have applications in the development of functional meat products of good technological quality that remain stable during storage. © 2016 Society of Chemical Industry.

Combined effect of carnosol, rosmarinic acid and thymol on the oxidative stability of soybean oil using a simplex centroid mixture design.

BACKGROUND: Oxidation taking place during the use of oil leads to the deterioration of both nutritional and sensorial qualities. Natural antioxidants from herbs and plants are rich in phenolic compounds and could therefore be more efficient than synthetic ones in preventing lipid oxidation reactions. This study was aimed at the valorization of Tunisian aromatic plants and their active compounds as new sources of natural antioxidant preventing oil oxidation. RESULTS: Carnosol, rosmarinic acid and thymol were isolated from Rosmarinus officinalis and Thymus capitatus by column chromatography and were analyzed by nuclear magnetic resonance. Their antioxidant activities were measured by DPPH, ABTS and FRAP assays. These active compounds were added to soybean oil in different proportions using a simplex-centroid mixture design. Antioxidant activity and oxidative stability of oils were determined before and after 20 days of accelerated oxidation at 60 °C. CONCLUSION: Results showed that bioactive compounds are effective in maintaining oxidative stability of soybean oil. However, the binary interaction of rosmarinic acid and thymol caused a reduction in antioxidant activity and oxidative stability of soybean oil. Optimum conditions for maximum antioxidant activity and oxidative stability were found to be an equal ternary mixture of carnosol, rosmarinic acid and thymol. © 2016 Society of Chemical Industry.

Eco-friendly process combining physical-chemical and biological technics for the fermented dairy products waste pretreatment and reuse.

Residual fermented dairy products resulting from process defects or from expired shelf life products are considered as waste. Thus, dairies wastewater treatment plants (WWTP) suffer high input effluents polluting load. In this study, fermented residuals separation from the plant wastewater is proposed. In the aim to meet the municipal WWTP input limits, a pretreatment combining physical-chemical and biological processes was investigated to reduce residual fermented dairy products polluting effect. Yoghurt (Y) and fermented milk products (RL) were considered. Raw samples chemical oxygen demand (COD) values were assessed at 152 and 246 g.L-1 for Y and RL products, respectively. Following the thermal coagulation, maximum removal rates were recorded at 80 °C. Resulting whey stabilization contributed to the removal rates enhance to reach 72% and 87% for Y and RL samples; respectively. Residual whey sugar content was fermented using Candida strains. Bacterial growth and strains degrading potential were discussed. C. krusei strain achieved the most important removal rates of 78% and 85% with Y and RL medium, respectively. Global COD removal rates exceeded 93%.

Balneicella halophila gen. nov., sp. nov., an anaerobic bacterium, isolated from a thermal spring and description of Balneicellaceae fam. nov.

A mesophilic anaerobic bacterium, designated KHALHBd91T was isolated from the moderately hot spring of Hammam Biadha, Tunisia. The strain was Gram-staining-negative, non-sporulating, non-motile and rod-shaped, appearing singly (0.5-2.0×0.5-1 µm). It grew anaerobically at temperatures between 20 and 50 °C (optimum 37 °C) and at pH values between 5.5 and 7.8 (optimum 7.0). It required NaCl for growth, with growth observed at up 8.5 % and an optimum at 2.5 %. KHALHBd91T used glucose, galactose, maltose, pyruvate, lactate, fumarate and yeast extract as electron donors. The end-products from glucose fermentation were acetate, propionate, succinate and CO2. Nitrate, nitrite, thiosulfate, elemental sulfur, sulfate and sulfite were not used as terminal electron acceptors. The predominant cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The respiratory quinone was MK-6. The main polar lipids consisted of lipids, phospholipids, glycolipids, aminolipids, phosphoaminoglycolipids and phosphatidylethanolamine. The DNA G+C content was 35.0 mol%. Phylogenetic analysis of the small-subunit ribosomal 16S rRNA gene sequence indicated that KHALHBd91T had Marinifilum fragile and Marinifilum flexuosum (phylum Bacteroidetes, class Bacteroidia, order Bacteroidales) as its closest relatives (similarity of 86.7 and 87.8 % respectively). The phylogenetic and physiological data fro the present study strongly indicate that the isolate represents a novel genus and species of a novel family, Balneicella halophila gen. nov., sp. nov., in the family Balneicellaceaefam. nov. The type strain is KHALHBd91T (=DSM28579T=JCM19909T).

Industrial textile effluent decolourization in stirred and static batch cultures of a new fungal strain Chaetomium globosum IMA1 KJ472923.

The treatment of an industrial textile effluent (ITE) was investigated by using a mono-culture of a novel fungal strain Chaetomium globosum IMA1. This filamentous fungus was selected based on its capacity for dye removal via the biodegradation mechanism. The respirometric analysis showed that C. globosum IMA1 was resistant to an indigo concentration up to 700 mg equivalent COD/L. The decolourization of the ITE by C. globosum was performed in static and stirred batch systems. The better lignin peroxidase (LiP), laccase and the manganese peroxidase (MnP) productions were 829.9 U/L, 83 U/L and 247.8 U/L, respectively since 3-5 days under a stirred condition. Therefore, the chemical oxygen demand (COD) and colors (OD620) removal yields reached 88.4% and 99.8%, respectively. Fourier transforms infrared spectroscopy (FTIR) analysis of the treated effluent showed that the decolourization was due to the degradation and the transformation of dye molecules. However, spectrophotometric examination showed that the complete dye removal was through fungal adsorption (8%), followed by degradation (92%).

Total coliphages removal by activated sludge process and their morphological diversity by transmission electron microscopy.

This study was conducted to isolate phages in treated sewage collected from wastewater treatment plant, and explore their morphological diversity by transmission electron microscopy (TEM). Fates of total bacteriophages and their reduction by biological treatment were also assayed. Phages were isolated using the plaque assay then negatively stained and observed by electron microscope. Electron micrographs showed different types of phages with different shapes and sizes. The majority of viruses found in treated sewage ranged from 30 to 100 nm in capsid diameter. Many of them were tailed, belonging to Siphoviridae, Myoviridae and Podoviridae families. Non-tailed phage particles were also found at a low rate, presumably belonging to Leviviridae or Microviridae families. This study shows the diversity and the abundance of bacteriophages in wastewater after biological treatment. Their persistence in wastewater reused in agriculture should raise concerns about their potential role in controlling bacterial populations in the environment. They should be also included in water treatment quality controlling guidelines as fecal and viral indicators.

Fusibacter bizertensis sp. nov., isolated from a corroded kerosene storage tank.

Strain LTF Kr01(T), a novel mesophilic, anaerobic, halotolerant, rod-shaped bacterium, was isolated from a drain at the bottom of a corroded kerosene storage tank of the Société Tunisienne des Industries de Raffinage (STIR), Bizerte, northern Tunisia. Cells were Gram-positive-staining rods, occurred singly or in pairs, and were motile by one lateral flagellum. Strain LTF Kr01(T) grew at temperatures between 15 and 40 °C (optimum 30 °C), between pH 5.5 and 8.2 (optimum pH 7.2) and at NaCl concentrations between 0 and 50 g l(-1) (optimum 5 g l(-1)). It reduced thiosulfate and elemental sulfur into sulfide, but did not reduce sulfate or sulfite. It utilized a wide range of carbohydrates (cellobiose, d-glucose, d-fructose, d-mannitol, d-ribose, sucrose, d-xylose, maltose, d-galactose, starch and trehalose) and produced acetate, CO2 and H2 as end products from glucose fermentation. The DNA G+C content was 37.4 mol%. The predominant cellular fatty acids were C14:0 and C16:0. Phylogenetic analysis of the 16S rRNA gene sequence suggested that Fusibacter tunisiensis was the closest relative of strain LTF Kr01(T) (gene sequence similarity of 94.6%). Based on phenotypic, phylogenetic and genotypic taxonomic characteristics, strain LTF Kr01(T) is proposed to represent a novel species of the genus Fusibacter, order Clostridiales, for which the name Fusibacter bizertensis sp. nov. is proposed. The type strain is LTF Kr01(T) ( = DSM 28034(T) = JCM 19376(T)).

Aminobacterium thunnarium sp. nov., a mesophilic, amino acid-degrading bacterium isolated from an anaerobic sludge digester, pertaining to the phylum Synergistetes.

A new Gram-staining-positive, non-sporulating, mesophilic, amino acid-degrading anaerobic bacterium, designated strain OTA 102(T), was isolated from an anaerobic sequencing batch reactor treating wastewater from cooking tuna. The cells were curved rods (0.6-2.5×0.5 µm) and occurred singly or in pairs. The strain was motile by means of one lateral flagellum. Strain OTA 102(T) grew at temperatures between 30 and 45 °C (optimum 40 °C), between pH 6.0 and 8.4 (optimum pH 7.2) and NaCl concentrations between 1 and 5 % (optimum 2 %, w/v). Strain OTA 102(T) required yeast extract for growth. Serine, threonine, glycine, cysteine, citrate, fumarate, α-ketoglutarate and pyruvate were fermented. When co-cultured with Methanobacterium formicicum as the hydrogen scavenger, strain OTA 102(T) oxidized alanine, valine, leucine, isoleucine, aspartate, tyrosine, methionine, histidine and asparagine. The genomic DNA G+C content of strain OTA 102(T) was 41.7 mol%. The main fatty acid was iso-C15 : 0. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain OTA 102(T) was related to Aminobacterium colombiense and Aminobacterium mobile (95.5 and 95.2 % similarity, respectively), of the phylum Synergistetes. On the basis of phylogenetic, genetic and physiological characteristics, strain OTA 102(T) is proposed to represent a novel species of the genus Aminobacterium, Aminobacterium thunnarium sp. nov. The type strain is OTA 102(T) ( = DSM 27500(T) = JCM 19320(T)).

Fusibacter fontis sp. nov., a sulfur-reducing, anaerobic bacterium isolated from a mesothermic Tunisian spring.

Strain KhalAKB1T, a mesophilic, anaerobic, rod-shaped bacterium, was isolated from water collected from a mesothermic Tunisian spring. Cells were Gram-staining-positive rods, occurring singly or in pairs and motile by one lateral flagellum. Strain KhalAKB1T grew at 15-45 °C (optimum 30 °C), at pH 5.5-8.5 (optimum pH 7.0) and in the presence of 0-35 g NaCl l- 1 (optimum 1 g NaCl l- 1). It fermented yeast extract and a wide range of carbohydrates including cellobiose, d-glucose, d-ribose, sucrose, d-xylose, maltose, d-galactose and starch as electron donors. Acetate, ethanol, CO2 and H2 were end products of glucose metabolism. It reduced elemental sulfur, but not sulfate, thiosulfate or sulfite, into sulfide. The DNA G+C content was 37.6 mol%. The predominant cellular fatty acids were C14 : 0 and C16 : 0. Phylogenetic analysis of the 16S rRNA gene sequence suggested Fusibacter bizertensis as the closest relative of this isolate (identity of 97.2 % to the type strain). Based on phenotypic, phylogenetic and genotypic taxonomic characteristics, strain KhalAKB1T is proposed to be assigned to a novel species within the genus Fusibacter, order Clostridiales, Fusibacter fontis sp. nov. The type strain is KhalAKB1T ( = DSM 28450T = JCM 19912T).

Characterization of Desulfovibrio biadhensis sp. nov., isolated from a thermal spring.

A novel anaerobic, mesophilic, slightly halophilic sulfate-reducing bacterium, designated strain Khaled BD4(T), was isolated from waters of a Tunisian thermal spring. Cells were vibrio-shaped or sigmoids (5-7×1-1.5 µm) and occurred singly or in pairs. Strain Khaled BD4(T) was Gram-stain-negative, motile and non-sporulated. It grew at 25-45 °C (optimum 37 °C), at pH 5.5-8.3 (optimum pH 7.0) and with 0.5-8% NaCl (optimum 3%). It required vitamins or yeast extract for growth. Sulfate, thiosulfate, sulfite and elemental sulfur served as terminal electron acceptors, but not fumarate, nitrate or nitrite. Strain Khaled BD4(T) utilized H2 in the presence of 2 mM acetate (carbon source), but also lactate, formate, pyruvate and fumarate in the presence of sulfate. Lactate was incompletely oxidized to acetate. Amongst substrates used, only pyruvate was fermented. Desulfoviridin and c-type cytochrome were present. The G+C content of the DNA was 54.6 mol%. The main fatty acids were anteiso -C(15 : 0), iso-C(18 : 0), iso-C(17 : 0) and iso-C(14 : 0). Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Khaled BD4(T) had Desulfovibrio giganteus DSM 4123(T) (96.7% similarity) as its closest phylogenetic relative. On the basis of 16S rRNA gene sequence comparisons together with genetic and physiological characteristics, strain Khaled BD4(T) is assigned to a novel bacterial species, for which the name Desulfovibrio biadhensis sp. nov. is proposed. The type strain is Khaled BD4(T) ( = DSM 28904(T) = JCM 30146(T)).