Production and characterization of soft Sardaigne-type cheese by using almond gum as a functional additive.

The effect of almond gum (AG), as natural polysaccharide with high nutritional value and important functional properties, on physicochemical and textural characteristics of Sardaigne-type cheese was investigated. Response surface methodology (RSM) using Box-Behnken design was applied to determine optimal levels of three selected processing variables such as coagulation temperature (25-45°C), stirring period (20-30 min), and AG concentration (0.25%-0.75%). A 3-level factorial design was employed to evaluate physicochemical and rheological responses of Sardaigne-type cheese with AG added. The P-values of ANOVA indicated that the processing variables selected have significantly affected dry matter content (p = .002), cheese yield (p = .0172), syneresis level (p = .0135), hardness (p = .0103), and adhesiveness (p = .0410). However, pH, cohesiveness, and elasticity are not affected by the selected processing variables. Predictive regression equations with a high coefficient of (R 2 ≥ .686) determination are constructed. The addition of AG owing to its water retention property has improved yield cheese as well moisture level. Therefore, this additional moisture in Sardaigne-type cheese will be responsible for softer and smoother textural. Indeed, fivefold drop of adhesiveness and fourfold reduction of hardness are observed in cheese formulated with AG at 0.75% and in same temperature and stirring period conditions that commercial cheese. RSM analysis showed that optimum levels of processing variables are reached at AG concentration of 0.57% (w/v), coagulation temperature of 42.57°C, and stirring period of 20 min. Results of sensory properties showed that AG incorporation in Sardaigne-type cheese does not have an adverse impact on organoleptically characteristics and overall acceptability of product was better than commercial cheese.

Profiling beneficial phytochemicals in a potato somatic hybrid for tuber peels processing: phenolic acids and anthocyanins composition.

The purpose of this study was to characterize the peels of a CN1 somatic hybrid obtained from two dihaploid potato lines (Cardinal H14 and Nicola H1) in terms of the health-promoting phenolic compounds (phenolic acids and anthocyanins). The CN1 hybrid is defined by a pink tuber skin color making it different from the light-yellow-skinned "Spunta," which is the most commonly grown potato cultivar in Tunisia. Oven-dried peel samples derived from CN1 hybrid and cv. Spunta were ground, and phenolic compounds were extracted with water or methanol for quantification. Lyophilized peels were used for the phenolic acid and anthocyanin analyses. Higher total quantities of phenolic compounds were recovered in methanol extracts compared with water extracts. A slightly higher concentration of phenolic acids (100 mg/100 g DW) was obtained in the lyophilized peels extract of CN1 hybrid than in the cv. Spunta corresponding sample (83 mg/100 g DW). The profiles of the chlorogenic acid isomers were almost identical in both of CN1 hybrid and cv. Spunta. Caffeic acid (CA) and three caffeoylquinic acids (CQAs): 3-CQA, 4-CQA, and 5-CQA, were identified from both genotypes, 5-CQA being the dominant form in both potatoes. Since the CN1 hybrid has a pink skin color, its anthocyanin profile was also determined. The anthocyanin quantity in the CN1 peels was 5.07 mg/100 g DW, involving six different anthocyanins that were identified within the extract, namely, Pelargonidin-3-rutinoside-5-glucoside, peonidin-3-rutinoside-5-glucoside, coumaroyl ester of pelargonidin-3-rutinoside-5-glucoside, coumaroyl ester of peonidin-3-rutinoside-5-glucoside, feruloyl ester of pelargonidin-3-rutinoside-5-glucoside, and feruloyl ester of peonidin-3-rutinoside-5-glucoside. These results suggest that the peel waste of CN1 somatic hybrid can be considered as a promising source of high-value compounds for food industry.

Penconazole alters redox status, cholinergic function and lung's histoarchitecture of adult rats: Reversal effect of vitamin E.

The present study pertains to the possible adverse effects of penconazole exposure on the lung of adult rats, and to the potential ability of vitamin E (Vit E) in mitigating the toxicity induced by this fungicide. Male Wistar rats were divided into four groups of six animals each: Group I (Controls): rats drank distilled water; Group II (PEN): rats received, by gavage, 50 mg/kg body weight (1/40 LD50) of penconazole every 2 days during 10 days; Group III (Vit E): rats received daily 100 mg α-tocopherol acetate/kg body weight during 10 days by gavage; and Group IV (Vit E + PEN): rats received both vitamin E (100 mg α-tocopherol acetate/kg body weight) and penconazole (50 mg/kg body weight), being vitamin E given as a daily dosage and penconazole every 2 days, by gavage during 10 days. Results showed that penconazole induced oxidative stress in the lung demonstrated by an increase in malondialdehyde (+77%), hydrogen peroxide (+58%) and advanced oxidation protein product (+22%) levels, as compared to the controls. Furthermore, a decrease in the activities of catalase (-41%), superoxide dismutase (-45%), glutathione peroxidase (-23%) and acetylcholinesterase (-67%), and an increase in the levels of non-protein thiols (+17%), glutathione (+7%) and vitamin C (+44%) were registered. Abnormalities in lung histological sections such as alveolar edema, infiltration of inflammatory cells (leukocytes) and emphysema, were also observed following penconazole exposure. Vitamin E ameliorated the biochemical parameters, as well as the histological impairments induced by this fungicide. In conclusion, our study demonstrated that vitamin E, a natural antioxidant, was effective in alleviating penconazole-induced lung damage in Wistar rats.

Improved Biosurfactant Production by Bacillus subtilis SPB1 Mutant Obtained by Random Mutagenesis and Its Application in Enhanced Oil Recovery in a Sand System.

Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of environmental bioremediation as well as the petroleum industry and enhanced oil recovery. However, the major issues in biosurfactant production are high production cost and low yield. Improving the bioindustrial production processes relies on many strategies, such as the use of cheap raw materials, the optimization of medium-culture conditions, and selecting hyperproducing strains. The present work aims to obtain a mutant with higher biosurfactant production through applying mutagenesis on Bacillus subtilis SPB1 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on blood agar and subsequent formation of halos, the mutated strains were examined for emulsifying activity of their culture broth. A mutant designated B. subtilis M2 was selected as it produced biosurfactant at twice higher concentration than the parent strain. The potential of this biosurfactant for industrial uses was shown by studying its stability to environmental stresses such as pH and temperature and its applicability in the oil recovery process. It was practically stable at high temperature and at a wide range of pH, and it recovered above 90% of motor oil adsorbed to a sand sample.

Potential application of Bacillus subtilis SPB1 biosurfactants in laundry detergent formulations: Compatibility study with detergent ingredients and washing performance.

Surfactants play a very important role in laundry and household cleaning products ingredients. In this research, the application of lipopeptide biosurfactants, produced by Bacillus subtilis SPB1, in the formulation of a washing powder was investigated. The SPB1 biosurfactant was mixed with sodium tripolyphosphate as a builder and sodium sulfate as filler. The efficiency of the formulated detergent composition with different washing conditions to remove a stain from cotton fabric was examined. The results showed that the formulated detergent was effective in oil removal, with optimal washing conditions of pH, temperature, striate and time of washing system of 7, 65°C, 1000 RPM and 60 min, respectively. A comparative study of different detergent compositions (biosurfactant-based detergent, combined biosurfactant-commercial detergent, and a commercial detergent) for the removal of oil and tea stains, proved that the bio-scouring was more effective (>75%) in terms of the stain removal than the commercial powders (<60%). Moreover, the results demonstrated that the biosurfactant acts additively with a commercial detergent and enhances their performance from 33 to 45% in removing oil stain and from 57 to 64% in removing tea stain. As a conclusion, in addition to the low toxicity and the high biodegradability of the microbial biosurfactants, the results of this study have shown that the future use of this lipopeptide biosurfactant as laundry detergent additive is highly promising.

Nitraria retusa fruit prevents penconazole-induced kidney injury in adult rats through modulation of oxidative stress and histopathological changes.

CONTEXT: Nitraria retusa (Forssk.) Asch. (Nitrariaceae) is a medicinal plant which produces edible fruits whose antioxidant activity has been demonstrated. OBJECTIVE: The current study elucidates the potential protective effect of N. retusa fruit aqueous extract against nephrotoxicity induced by penconazole, a triazole fungicide, in the kidney of adult rats. MATERIALS AND METHODS: Adult Wistar rats were exposed either to penconazole (67 mg/kg body weight), or to N. retusa extract (300 mg/kg body weight) or to their combination. Penconazole was administered by intra-peritoneal injection every 2 days from day 7 until day 15, the sacrifice day, while N. retusa extract was administered daily by gavage during 15 days. Oxidative stress parameters, kidney biomarkers and histopathological examination were determined. RESULTS: Nitraria retusa extract administration to penconazole treated rats decreased kidney levels of malondialdehyde (-10%), hydrogen peroxide (-12%), protein carbonyls (PCOs, -11%) and advanced oxidation protein products (AOPP, -16%); antioxidant enzyme activities: catalase (-13%), superoxide dismutase (-8%) and glutathione peroxidase (GPx, -14%), and the levels of non-enzymatic antioxidants: non-protein thiols (-9%), glutathione (-7%) and metallothionein (-12%). Furthermore, this plant extract prevented kidney biomarker changes by reducing plasma levels of creatinine, urea, uric acid and LDH and increasing those of ALP and GGT. Histopathological alterations induced by penconazole (glomeruli fragmentation, Bowman's space enlargement, tubular epithelial cells necrosis and infiltration of inflammatory leucocytes) were attenuated following N. retusa administration. DISCUSSION AND CONCLUSION: Our results indicated that N. retusa fruit extract had protective effects against penconazole-induced kidney injury, which could be attributed to its phenolic compounds.

Evaluation of Bacillus subtilis SPB1 biosurfactant effects on hyperglycemia, angiotensin I-converting enzyme (ACE) activity and kidney function in rats fed on high-fat-high-fructose diet.

This study investigated the protective and the curative effects of Bacillus subtilis SPB1 crude lipopeptide biosurfactant in alleviating induced obesity complications in rats fed on high-fat-high-fructose diet (HFFD). Male Wistar rats were divided into five groups with the following treatment schedule: normal diet-fed rats (CD), HFFD-fed rats, HFFD-fed rats supplemented with SPB1 biosurfactant from the first day of the experiment (HFFD + Bios1), rats fed on HFFD receiving standard drug (HFFD + Torva), or SPB1 biosurfactant (HFFD + Bios2) during the last 4 weeks of the study. HFFD induced hyperglycemia, manifested by a significant (p < 0.001) increase (20%) in the levels of glucose and α-amylase activity in the plasma, when compared with CD. The administration of SPB1 biosurfactant to rats fed on HFFD reverted back normal blood glucose and α-amylase activity levels. Also, the findings clearly showed that acute oral administration of SPB1 biosurfactant reduced significantly (34%) the peak of blood glucose concentration 60 min after glucose administration, as compared with untreated rats fed on HFFD. Furthermore, renal dysfunction indices such as creatinine and urea as well as the level of angiotensin I-converting enzyme (ACE) exhibited remarkable increases in serum of rats fed on HFFD by 28.35%, 46%, and 92%,. Interestingly, SPB1 lipopeptides treatments decreased the creatinine and urea levels significantly (p < 0.001) near normal values, as compared with that of the HFFD group, and also showed an improvement of the kidney cortex architecture. Moreover, SPB1 biosurfactant displayed a potent inhibition of ACE activity in vitro (CI50 value= 1.37 mg/mL) as well as in vivo in obese rats by 42% and 27.25% with HFFD + Bios1 and HFFD + Bios2 treatments, respectively, and comparatively with the HFFD group. Besides, SPB1 lipopeptides treatments improved some of serum electrolytes such as Na+, K+, Ca2+ , and Mg2+. The results showed that SPB1 lipopeptide biosurfactant presented useful hypoglycemic and antihypertensive properties, and was able to alleviate renal lipid deposition in rats fed on a hypercaloric diet.

Evaluation of dermal wound healing and in vitro antioxidant efficiency of Bacillus subtilis SPB1 biosurfactant.

BACKGROUND: Lipopeptide microbial surfactants are endowed with unique surface properties as well as antimicrobial, anti-wrinkle, moisturizing and free radical scavenging activities. They were introduced safely in dermatological products, as long as they present low cytotoxicity against human cells. The present study was undertaken to evaluate the in vitro antioxidant activities and the wound healing potential of Bacillus subtilis SPB1 lipopeptide biosurfactant on excision wounds induced in experimental rats. RESULTS: The scavenging effect of Bacillus subtilis SPB1 biosurfactant on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical at 1mg/mL was 70.4% (IC50=0.55mg/mL). The biosurfactant produced by Bacillus subtilis SPB1 also showed good reducing power and significant effects in terms of the ß-carotene test (IC50=2.26mg/mL) when compared to BHA as a reference standard. Moreover, an interesting ferrous ion chelating activity (80.32%) was found for SPB1 biosurfactant at 1mg/mL. Furthermore, the topical application of Bacillus subtilis SPB1 biosurfactant based gel on the wound site in a rat model every two days, increased significantly the percentage of wound closure over a period of 13days, when compared to the untreated and CICAFLORA™-treated groups. Wound healing effect of SPB1 biosurfactant based gel was confirmed by histological study. Biopsies treated with SPB1 lipopeptides showed wholly re-epithelialized wound with a perfect epidermal regeneration. CONCLUSIONS: The present study provides justification for the use of Bacillus subtilis SPB1 lipopeptide biosurfactant based gel for the treatment of normal and complicated wounds as well as skin diseases.

Protective and curative effects of Bacillus subtilis SPB1 biosurfactant on high-fat-high-fructose diet induced hyperlipidemia, hypertriglyceridemia and deterioration of liver function in rats.

This study was aimed to assess the plausible anti-obesity effects of Bacillus subtilis SPB1 crude lipopeptide biosurfactant on high fat high fructose diet-fed rats (HFFD). Male Wistar rats were divided into five groups with the following treatment schedule: normal diet (CD), HFFD, HFFD supplemented with SPB1 biosurfactant from the first day of the experiment (HFFD+Bios1, 10mg/kg/day), HFFD receiving standard drug (HFFD+Torva, 10mg/kg/day) or SPB1 biosurfactant (HFFD+Bios2, 10mg/kg/day) during the last 4 weeks of the study. The results showed an increase in body weight of HFFD by ∼19% as compared to controls (CD). Moreover, serum lipase activity underwent a threefold increase which led to an increase in the levels of total cholesterol (T-Ch), triglycerides (TG) and LDL-cholesterol (LDL-Ch) in serum of untreated HFFD, as well as a rise in the calculated atherogenic index (AI). Furthermore, liver dysfunction indices such as AST, ALT, CPK, LDH, GGT, ALP and T-Bilirubins exhibited remarkable increases in serum of HFFD as compared to controls (CD). Whereas, the administration of Bacillus subtilis SPB1 biosurfactant to HFFD improved the body weight gain and serum lipids profile and reverted back near normal the activities of lipase and liver toxicity indicators. In addition, notable protective and curative effects were reported in liver tissues. Overall, these results suggest that the lipopeptides biosynthesized by Bacillus subtilis SPB1 achieved an anti-obesity effect through the inhibition of lipid digestive and liver dysfunction enzymes.

Cookies from composite wheat-sesame peels flours: dough quality and effect of Bacillus subtilis SPB1 biosurfactant addition.

Sesame coat is a valuable by-product. The study was carried out on sesame peels flour at different replacing levels of white wheat flour in five cookies dough formulations. The functional properties of composite flours such as swelling capacity, water holding capacity, oil holding capacity, emulsifying capacity, foam capacity, gelatinization temperature, least gelation concentration and bulk density were increased with increase in the sesame peels flour incorporation along with wheat flour. Texture analysis of dough revealed that, the addition of sesame peels flour affected the quality of dough in terms of hardness, cohesion, adhesion and breaking strength. Cookies supplemented with sesame peels flour showed interesting physical properties with lower moisture content and higher spread factor than those made by white wheat flour. But, their hardness increase with the increase of the replacement ratio and their color becomes indesirable. Interestingly, sensory results indicated that cookies supplemented with sesame peels flour were acceptable at a level that not exceeds 30% of incorporation. By the addition of SPB1 biosurfactant at 0.1%, the dough texture profile was significantly improved and the action of this bioemulsifier was more pronounced than a commercial emulsifier known as glycerol monostearate. With the addition of SPB1 biosurfactant on cookies' dough, we manage to obtain cookies softer and with better overall quality.

Co-exposure to aluminum and acrylamide disturbs expression of metallothionein, proinflammatory cytokines and induces genotoxicity: Biochemical and histopathological changes in the kidney of adult rats.

The individual toxic effects of aluminum and acrylamide are known but there is no data on their combined effects. The present study investigates the toxic effects after combined exposure to these toxicants on: (i) oxidative stress during combined chronic exposure to aluminum and acrylamide on kidney function (ii) correlation of oxidative stress with metallothionein (MT) and inflammatory cytokines expression, DNA damage, and histopathological changes. Rats were exposed to aluminum (50 mg/kg body weight) in drinking water and acrylamide (20 mg/kg body weight) by gavage either individually or in combination for 3 weeks. Exposure rats to aluminum chloride or acrylamide alone and in combination induced nephrotoxicity, as evidenced by a decrease in the 24-h urine volume and uric acid levels in plasma and an increase of plasma creatinine, urea, and blood urea nitrogen levels. Nephrotoxicity was objectified by a significant increase in malondialdehyde level, advanced oxidation protein, and protein carbonyl contents, whereas reduced glutathione, nonprotein thiol, vitamin C levels, catalase, and glutathione peroxidase activities showed a significant decline. Superoxide dismutase activity and its gene expression were increased. Aluminum and acrylamide co-exposure exhibited synergism in various biochemical variables and also in DNA damage. Kidney total MT levels and genes expression of MT1, MT2, and proinflammatory cytokines were increased. All these changes were supported by histopathological observations. Co-exposure to aluminum and acrylamide exhibited synergism and more pronounced toxic effects compared with their individual effects based on various biochemical variables, genotoxic, and histopathological changes. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1044-1058, 2016.

Assessment of the antidiabetic and antilipidemic properties of Bacillus subtilis SPB1 biosurfactant in alloxan-induced diabetic rats.

The present study aimed to scrutinize the potential of Bacillus subtilis SPB1biosurfactant, orally administered, for preventing diabetic complications in rats. The findings revealed that, Bacillus subtilis biosurfactant was an effective reducer of α-amylase activity in the plasma. Moreover, this supplement helped protect the ß-cells from death and damage. Both the inhibitory action of SPB1 biosurfactant on α-amylase and the protection of the pancreas' ß-cells lead to a decrease of the blood glucose levels, consequently antihyperglycemic effect. Interestingly, this lipopeptide biosurfactant modulated key enzyme related to hyperlipidemia as lipase; which leads to the regulation of the lipid profile in serum by the delay in the absorption of LDL-cholesterol and triglycerides, and a significant increase in HDL-cholesterol. Histological analyses also showed that it exerted a protective action on the pancreases and efficiently preserved the liver-kidney functions of diabetic rats, evidenced by significant decreases in aspartate transaminase, alanine transaminase, gamma-glytamyl transpeptidase and lactate deshydrogenase activities in the plasma, as well as in the creatinine and urea contents. Overall, the present study demonstrated that the hypoglycemic and antilipidemic activities exhibited by Bacillus subtilis biosurfactant were effective enough to alleviate induced diabetes in experimental rats. Therefore, SPB1biosurfactant could be considered as a potential strong candidate for the treatment and prevention of diabetes.

Antifungal efficiency of a lipopeptide biosurfactant derived from Bacillus subtilis SPB1 versus the phytopathogenic fungus, Fusarium solani.

Bacillus subtilis SPB1 lipopeptides were evaluated as a natural antifungal agent against Fusarium solani infestation. In vitro antifungal assay showed a minimal inhibitory concentration of about 3 mg/ml with a fungicidal mode of action. In fact, treatment of F. solani by SPB1 lipopeptides generated excessive lyses of the mycelium and caused polynucleation and destruction of the related spores together with a total inhibition of spore production. Furthermore, an inhibition of germination potency accompanied with a high spore blowing was observed. Moreover, in order to be applied in agricultural field, in vivo antifungal activity was proved against the dry rot potato tubers caused by F. solani. Preventive treatment appeared as the most promising as after 20 days of fungi inoculation, rot invasion was reduced by almost 78%, in comparison to that of non-treated one. When treating infected tomato plants, disease symptoms were reduced by almost 100% when applying the curative method. Results of this study are very promising as it enables the use of the crude lipopeptide preparation of B. subtilis SPB1 as a potent natural fungicide that could effectively control the infection of F. solani in tomato and potato tubers at a concentration similar to the commercial fungicide hymexazol and therefore prevent the damage of olive tree.

Biodegradation of diesel oil by a novel microbial consortium: comparison between co-inoculation with biosurfactant-producing strain and exogenously added biosurfactants.

Bioremediation, involving the use of microorganisms to detoxify or remove pollutants, is the most interesting strategy for hydrocarbon remediation. In this aim, four hydrocarbon-degrading bacteria were isolated from oil-contaminated soil in Tunisia. They were identified by the 16S rDNA sequence analysis, as Lysinibacillus bronitolerans RI18 (KF964487), Bacillus thuringiensis RI16 (KM111604), Bacillus weihenstephanensis RI12 (KM094930), and Acinetobacter radioresistens RI7 (KJ829530). Moreover, a lipopeptide biosurfactant produced by Bacillus subtilis SPB1, confirmed to increase diesel solubility, was tested to increase diesel biodegradation along with co-inoculation with two biosurfactant-producing strains. Culture studies revealed the enhancement of diesel biodegradation by the selected consortium with the addition of SPB1 lipopeptide and in the cases of co-inoculation by biosurfactant-producing strain. In fact, an improvement of about 38.42 and 49.65 % of diesel degradation was registered in the presence of 0.1 % lipopeptide biosurfactant and when culturing B. subtilis SPB1 strain with the isolated consortium, respectively. Furthermore, the best improvement, evaluated to about 55.4 %, was recorded when using the consortium cultured with B. subtilis SPB1 and A. radioresistens RI7 strains. Gas chromatography analyses were correlated with the gravimetric evaluation of the residual hydrocarbons. Results suggested the potential applicability of the selected consortium along with the ex situ- and in situ-added biosurfactant for the effective bioremediation of diesel-contaminated water and soil.

Disruption of erythrocyte antioxidant defense system, hematological parameters, induction of pro-inflammatory cytokines and DNA damage in liver of co-exposed rats to aluminium and acrylamide.

The individual toxic effects of aluminium and acrylamide are well known but there are no data on their combined effects. The present study was undertaken to determine (i) hematological parameters during individual and combined chronic exposure to aluminium and acrylamide (ii) correlation of oxidative stress in erythrocytes with pro-inflammatory cytokines expression, DNA damage and histopathological changes in the liver. Rats were exposed to aluminium (50 mg/kg body weight) in drinking water and acrylamide (20 mg/kg body weight) by gavage, either individually or in combination for 3 weeks. Exposure rats to AlCl3 or/and ACR provoked an increase in MDA, AOPP, H2O2 and a decrease in GSH and NPSH levels in erythrocytes. Activities of catalase, glutathione peroxidase and superoxide dismutase were decreased in all treated rats. Our results showed that all treatments induced an increase in WBC, erythrocyte osmotic fragility and a decrease in RBC, Hb and Ht. While MCV, MCH, MCHC remained unchanged. Hepatic pro-inflammatory cytokines expression including tumor necrosis factor-α, interleukin-6, interleukin-1ß was increased suggesting leucocytes infiltration in the liver. A random DNA degradation was observed on agarose gel only in the liver of co-exposed rats to AlCl3 and ACR treatment. Interestingly, co-exposure to these toxicants exhibited synergism based on physical and biochemical variables in erythrocytes, pro-inflammatory cytokines and DNA damage in liver.

Treatment of diesel- and kerosene-contaminated water by B. subtilis SPB1 biosurfactant-producing strain.

This study investigated the efficiency of hydrocarbon utilization by B. subtilis SPB1, a biosurfactant-producing strain. Microbial growth, biosurfactant production, and hydrocarbon biodegradation were studied in a liquid mineral medium, supplemented with 2% hydrocarbons in both the absence and in the presence of 0.1% yeast extract. Preliminary studies showed that maximum growth was registered with a 2% hydrocarbon solution. Results showed that the addition of yeast extract greatly stimulated microbial growth and thus induced biosurfactant production. Furthermore, biodegradation efficiencies were higher in the presence of yeast extract. Kerosene fuel was more recalcitrant to biodegradation than diesel oil. This study's findings suggest that the addition of an organic nitrogen source stimulates tension-active agents' production, which emulsifies hydrophobic compounds and enhances their biodegradation and microbial growth.

Evaluation of B. subtilis SPB1 biosurfactants' potency for diesel-contaminated soil washing: optimization of oil desorption using Taguchi design.

Low solubility of certain hydrophobic soil contaminants limits remediation process. Surface-active compounds can improve the solubility and removal of hydrophobic compounds from contaminated soils and, consequently, their biodegradation. Hence, this paper aims to study desorption efficiency of oil from soil of SPB1 lipopeptide biosurfactant. The effect of different physicochemical parameters on desorption potency was assessed. Taguchi experimental design method was applied in order to enhance the desorption capacity and establish the best washing parameters. Mobilization potency was compared to those of chemical surfactants under the newly defined conditions. Better desorption capacity was obtained using 0.1% biosurfacatnt solution and the mobilization potency shows great tolerance to acidic and alkaline pH values and salinity. Results show an optimum value of oil removal from diesel-contaminated soil of about 87%. The optimum washing conditions for surfactant solution volume, biosurfactant concentration, agitation speed, temperature, and time were found to be 12 ml/g of soil, 0.1% biosurfactant, 200 rpm, 30 °C, and 24 h, respectively. The obtained results were compared to those of SDS and Tween 80 at the optimal conditions described above, and the study reveals an effectiveness of SPB1 biosurfactant comparable to the reported chemical emulsifiers. (1) The obtained findings suggest (a) the competence of Bacillus subtilis biosurfactant in promoting diesel desorption from soil towards chemical surfactants and (b) the applicability of this method in decontaminating crude oil-contaminated soil and, therefore, improving bioavailability of hydrophobic compounds. (2) The obtained findings also suggest the adequacy of Taguchi design in promoting process efficiency. Our findings suggest that preoptimized desorption process using microbial-derived emulsifier can contribute significantly to enhancement of hydrophobic pollutants' bioavailability. This study can be complemented with the investigation of potential role in improving the biodegradation of the diesel adsorbed to the soil.

Improvement of bread dough quality by Bacillus subtilis SPB1 biosurfactant addition: optimized extraction using response surface methodology.

BACKGROUND: Statistically based experimental designs were applied to Bacillus subtilis SPB1 biosurfactant extraction. The extracted biosurfactant was tested as an additive in dough formulation. RESULTS: The Plackett-Burman screening method showed that methanol volume, agitation speed and operating temperature affect biosurfactant extraction. The effect was studied and adjusted using response surface methodology. The optimal values were identified as 5 mL methanol, 180 rpm and 25 °C, yielding predicted responses of 2.1 ± 0.06 for the purification factor and 87.47% ± 1.58 for the retention yield. Study of the incorporation of purified lipopeptide powder into the dough preparation in comparison with a commercial surfactant - soya lecithin - reveal that SPB1 biosurfactant significantly improves the textural properties of dough (hardness, springiness, cohesion and adhesion) especially at 0.5 g kg⁻¹. At the same concentration (0.5 g kg⁻¹), the effect of SPB1 biosurfactant was more pronounced than that of soya lecithin. Also, this biosurfactant considerably enhanced the gas retention capacity in the course of fermentation. CONCLUSION: These results show that SPB1 biosurfactant could be of great interest in the bread-making industry. A method for preparative extraction of lipopeptide biosurfactant with methanol as the extraction solvent has been effectively established.

Optimization of Inocula Conditions for Enhanced Biosurfactant Production by Bacillus subtilis SPB1, in Submerged Culture, Using Box-Behnken Design.

The inoculum age and density can influence considerably the production yield and cost of the fermentation process. Some literature studies report the use of two-stage inocula to enhance metabolite production. In the present study, optimization studies were done in order to define the best inocula conditions supporting a maximum biosurfactant production by Bacillus subtilis SPB1. Hence, by adjusting the levels of the two-stage inocula strategy, lipopeptide production was effectively enhanced to almost 3.4 g/l as estimated gravimetrically. The new defined parameters were as follows; a first inoculum age of 23 h followed by a second inoculum age and size of 4 h and 0.01, respectively. Thereby, we note an improved production as compared to the production yield described under non-optimized inocula conditions reported in our previous work.

The impact of the Bacillus subtilis SPB1 biosurfactant on the midgut histology of Spodoptera littoralis (Lepidoptera: Noctuidae) and determination of its putative receptor.

SPB1 is a Bacillus subtilis strain producing a lipopeptide biosurfactant. The insecticidal activity of this biosurfactant was evaluated against the Egyptian cotton leaf worm (Spodoptera littoralis). It displayed toxicity with an LC(50) of 251 ng/cm(2). The histopathological changes occurred in the larval midgut of S. littoralis treated with B. subtilis SPB1 biosurfactant were vesicle formation in the apical region, cellular vacuolization and destruction of epithelial cells and their boundaries. Ligand-blotting experiments with S. littoralis brush border membrane vesicles showed binding of SPB1 biosurfactant to a protein of 45 kDa corresponding to its putative receptor. The latter differs in molecular size from those recognized by Bacillus thuringiensis Vip3A and Cry1C toxins, commonly known by their activity against S. littoralis. This result wires the application of B. subtilis biosurfactant for effective control of S. littoralis larvae, particularly in the cases where S. littoralis will develop resistance against B. thuringiensis toxins.