Selected Carbon Sources Research Articles

Pea-Derived Raffinose-Family Oligosaccharides as a Novel Ingredient to Accelerate Sour Beer Production.

This study investigated raffinose family oligosaccharides (RFOs) derived from pulses as selective carbon sources for sour beer production. Fourteen lactic acid bacteria (LAB) were screened for growth in media supplemented with RFOs. Furthermore, the influence of ethanol and isomerized α-acids on the bacterial growth was investigated. While most LAB grew in the presence of RFOs, few did so in the presence of ethanol and α-acids. Some of the LAB with tolerance to these stressors were then combined with Brettanomyces claussenii to create classic-style sour beers with or without RFOs. These were characterized chemically, physically, and sensorially. Sour beers made with RFOs were evaluated as being comparable to a commercial Belgian sour beer for some sensory characteristics. Furthermore, the sensory analysis revealed significantly increased acidity levels and differences in flavor and taste between beers fermented with and without RFOs, which was underpinned by chemical analysis. Crucially, beany off-flavors, which are a common problem with pulse-derived ingredients, did not increase upon RFO addition. Thus, by combining selected LAB with RFOs, we successfully utilized a food sidestream and expanded the possibilities for brewing sour beers in a controlled manner in a short time. This is in contrast to the lengthy process used for traditional sour beers.

Exploration of Pseudomonas knackmussii AD02 for the biological mitigation of post-harvest aflatoxin contamination: Characterization and degradation mechanism

Exploration of Pseudomonas knackmussii AD02 for the biological mitigation of post-harvest aflatoxin contamination: Characterization and degradation mechanism

Lipid Accumulation by Snf-β Engineered Mucor circinelloides Strains on Glucose and Xylose.

Sucrose non-fermenting 1 (SNF1) protein kinase plays the regulatory roles in the utilization of selective carbon sources and lipid metabolism. Previously, the role of β subunit of SNF1 in lipid accumulation was evaluated by overexpression and knockout of Snf-β in oleaginous fungus M. circinelloides. In the present study, the growth and lipid accumulation of Snf-β overexpression and knockout strains were further analyzed and compared with glucose or xylose as a single or mixed carbon sources. The results showed that the lipid contents in Snf-β knockout strain improved by 23.2% (for glucose), 28.4% (for xylose), and 30.5% (for mixed glucose and xylose) compared with that of the control strain, respectively. The deletion of Snf-β subunit also altered the transcriptional level of acetyl-CoA carboxylase (ACC). The highest transcriptional levels of ACC1 in Snf-β knockout strain at 24h were increased by 2.4-fold (for glucose), 2.8-fold (for xylose), and 3.1-fold (for mixed glucose and xylose) compared with that of the control strain, respectively. Our results indicated that Snf-β subunit enhanced lipid accumulation through the regulation of ACC1 in response to xylose or mixed sugars of glucose and xylose more significantly than that of response to glucose. This is the first study to explore the effect of Snf-β subunit of M. circinelloides in regulating lipid accumulation responding to different carbon nutrient signals of glucose and xylose. This study provides a foundation for the future application of the Snf-β engineered strains in lipid production from lignocellulose.

Assessment of Starters of Lactic Acid Bacteria and Killer Yeasts: Selected Strains in Lab-Scale Fermentations of Table Olives (Olea europaea L.) cv. Leccino

Olives debittering, organoleptic quality and safety can be improved with yeasts and lactic acid bacteria (LABs) selected strain starters, that allow for better fermentation control with respect to natural fermentation. Two selected killer yeasts (Wickerhamomyces anomalus and Saccharomyces cerevisiae) and Lactobacillus plantarum strains were tested for olive (cv. Leccino) fermentation to compare different starter combinations and strategies; the aim was to assess their potential in avoiding pretreatments and the use of excessive salt in the brines and preservatives. Lactobacilli, yeasts, molds, Enterobacteriaceae and total aerobic bacteria were detected, as well as pH, soluble sugars, alcohols, organic acids, phenolic compounds, and rheological properties of olives. Sugars were rapidly consumed in the brines and olives; the pH dropped quickly, then rose until neutrality after six months. The oleuropein final levels in olives were unaffected by the treatments. The use of starters did not improve the LABs’ growth nor prevent the growth of Enterobacteriaceae and molds. The growth of undesirable microorganisms could have been induced by the availability of selective carbon source such as mannitol, whose concentration in olive trees rise under drought stress. The possible role of climate change on the quality and safety of fermented foods should be furtherly investigated. The improvement of olives’ nutraceutical value can be induced by yeasts and LABs starters due to the higher production of hydroxytyrosol.

The power of light: Impact on the performance of biocontrol agents under minimal nutrient conditions.

The spectral distribution of light (different wavelength) has recently been identified as an important factor in the dynamics and function of leaf-associated microbes. This study investigated the impact of different wavelength on three commercial biocontrol agents (BCA): Bacillus amyloliquefaciens (BA), Pseudomonas chlororaphis (PC), and Streptomyces griseoviridis (SG). The impact of light exposure on sole carbon source utilization, biofilm formation, and biosurfactant production by the selected BCA was studied using phenotypic microarray (PM) including 190 sole carbon sources (OmniLog®, PM panels 1 and 2). The BCA were exposed to five monochromatic light conditions (420, 460, 530, 630, and 660 nm) and darkness during incubation, at an intensity of 50 μmol m-2 s-1. Light exposure together with specific carbon source increased respiration in all three BCA. Different wavelengths of light influenced sole carbon utilization for the different BCA, with BA and PC showing increased respiration when exposed to wavelengths within the blue spectrum (420 and 460 nm) while respiration of selected carbon sources by SG increased in the presence of red light (630 and 660 nm). Only one carbon source (capric acid) generated biosurfactant production in all three BCA. A combination of specific wavelength of light and sole carbon source increased biofilm formation in all three BCA. BA showed significantly higher biofilm formation when exposed to blue (460 nm) and green (530 nm) light and propagated in D-sucrose, D-fructose, and dulcitol. PC showed higher biofilm formation when exposed to blue light. Biofilm formation by SG increased when exposed to red light (630 nm) and propagated in citraconic acid. To increase attachment and success in BCA introduced into the phyllosphere, a suitable combination of light quality and nutrient conditions could be used.

Detailed analysis of metabolism reveals growth-rate-promoting interactions between Anaerostipes caccae and Bacteroides spp.

Human gut microbiota species which are next-generation probiotics (NGPs) candidates are of high interest as they have shown the potential to treat intestinal inflammation and other diseases. Unfortunately, these species are often not robust enough for large-scale cultivation, especially in maintaining diversity in co-culture production. In this study, we describe interactions between human gut microbiota species in the cultivation process with unique substrates. We also demonstrated that it is possible to change the species ratio in co-culture by changing the ratio of carbon sources. We screened 25 different bacterial species based on their metabolic capabilities. After evaluating unique substrate possibilities, we chose Anaerostipes caccae (A.caccae), Bacteroides thetaiotaomicron (B.thetaiotaomicron), and Bacteroides vulgatus (B.vulgatus) as subjects for further study. D-sorbitol, D-xylose, and D-galacturonic acid were selected as substrates for A.caccae, B.thetaiotaomicron, and B.vulgatus respectively. All three species were cultivated as both monocultures and in co-cultures in serial batch fermentations in an isothermal microcalorimeter. Positive interactions were detected between the species in both co-cultures (A.caccae+B.thetaiotaomicron; A.caccae+B.vulgatus) resulting in higher heat production compared to the sum of the monocultures. The same positive cross-feeding interactions took place in larger-scale cultivation experiments. We confirmed acetate and lactate cross-feeding between A.caccae and B.thetaiotaomicron with flux balance analysis (FBA). Changing the ratio of the selected carbon sources in the medium changed the species ratio accordingly. Such robustness is the basis for developing more efficient industrial co-culture processes including the production of NGPs.

Cadmium induced aggregation of orange–red emissive carbon dots with enhanced fluorescence for intracellular imaging

Cadmium is a notorious toxic heavy metal, that poses serious threat to human health. Sensitive and selective detection of cadmium in cells is of great significance in poison screening and disease diagnosis. Orange-red emissive carbon dots (OR-CDs), prepared from the calcination of selected carbon sources 5-amino-1, 10-phenanthroline (Aphen) and salicylic acid (SA), were found to act as a "turn on" type fluorescence probe for Cd2+ detection. The structure and optical properties of OR-CDs were comprehensively investigated by both experimental characterizations and density functional theory (DFT) calculations. The OR-CDs consist of a basic unit of nine aromatic rings, and the N/O binding sites on the OR-CDs can specifically bind with Cd2+, leading to aggregation induced enhanced emission (AIEE). A detection limit of 0.30μM was achieved for Cd2+ with a linear range of 0.80-100μM. OR-CDs can not only be used for intracellular Cd2+ imaging but also have the potential to alleviate cadmium poison in living organisms.

CcpA mutants influence selective carbon source utilization by changing interactions with target genes in Bacillus licheniformis

The gram-positive bacterium Bacillus licheniformis exhibits obvious selective utilization on carbon sources. This process is mainly governed by the global regulator catabolite control protein A (CcpA), which can recognize and bind to multiple target genes that are widely distributed in metabolic pathways. Although the DNA-binding domain of CcpA has been predicted, the influence of key amino acids on target gene recognition and binding has yet to be uncovered. In this study, the impact of Lys31, Ile42 and Leu56 on in vitro protein–DNA interactions and in vivo carbon source selective utilization was investigated. The results showed that alanine substitution of Lys31 and Ile42, located within the 3rd helices of the DNA-binding domain, significantly weakened the binding strength between CcpA and target genes. These mutations also lead to alleviated repression of xylose utilization in the presence of glucose. On the other hand, the Leu56Arg mutant in the 4th helices exhibited enhanced binding affinity compared with that of the wild-type one. When this mutant was used to replace the native one in B. licheniformis cells, the selective utilization of glucose over xylose increased. This study provides a new strategy for understanding the relationship between the function and structure of regulatory proteins. This study also used a new strategy was used to regulate carbon source utilization beyond CCR engineering.

Selective carbon sources influence the end products of microbial nitrate respiration

Respiratory and catabolic genes are differentially distributed across microbial genomes. Thus, specific carbon sources may favor different respiratory processes. We profiled the influence of 94 carbon sources on the end products of nitrate respiration in microbial enrichment cultures from diverse terrestrial environments. We found that some carbon sources consistently favor dissimilatory nitrate reduction to ammonium (DNRA/nitrate ammonification) while other carbon sources favor nitrite accumulation or denitrification. For an enrichment culture from aquatic sediment, we sequenced the genomes of the most abundant strains, matched these genomes to 16S rDNA exact sequence variants (ESVs), and used 16S rDNA amplicon sequencing to track the differential enrichment of functionally distinct ESVs on different carbon sources. We found that changes in the abundances of strains with different genetic potentials for nitrite accumulation, DNRA or denitrification were correlated with the nitrite or ammonium concentrations in the enrichment cultures recovered on different carbon sources. Specifically, we found that either L-sorbose or D-cellobiose enriched for a Klebsiella nitrite accumulator, other sugars enriched for an Escherichia nitrate ammonifier, and citrate or formate enriched for a Pseudomonas denitrifier and a Sulfurospirillum nitrate ammonifier. Our results add important nuance to the current paradigm that higher concentrations of carbon will always favor DNRA over denitrification or nitrite accumulation, and we propose that, in some cases, carbon composition can be as important as carbon concentration in determining nitrate respiratory end products. Furthermore, our approach can be extended to other environments and metabolisms to characterize how selective parameters influence microbial community composition, gene content, and function.

Structural and metabolic performance of p-cresol producing microbiota in different carbon sources

p-Cresol (PC) is a potential off-flavor and carcinogenic compound that affects food flavor and safety. However, controlling the production of PC when making fermented food is hindered by a lack of knowledge of the microbial diversity and the growth requirements of the microbiota that produce PC. To address this, the present study used three media with selected carbon sources (glucose, ethanol and lactic acid) to explore the microbial origin of PC and to determine the preferred carbon source for the PC-producing microbiota in the pit mud of the strong-aroma type Baijiu. The results showed that the different carbon sources affected the microbial structure, especially of the PC-producing microbiota. Glucose led to the highest production of PC and lactic acid to the lowest. The production of PC was significantly correlated (p<0.05, |ρ|>0.6) with Dorea, Sporanaerobacter, Tepidimicrobium, Tissierella Soehngenia, Clostridium and Sedimentibacter in the glucose medium; with Proteiniborus, Ruminococcus and Sporanaerobacter in the ethanol medium; and with Lutispora and Tepidimicrobium in the lactic acid medium. Multiphasic metabolite target analysis further indicated that the PC-producing microbiota could also metabolize flavor compounds. Lactic acid could inhibit the production of PC and ensure that the microbiota produced the appropriate flavor compounds during culture. Collectively, Dorea, Sporanaerobacter, Tepidimicrobium, Tissierella_Soehngenia, Clostridium, Sedimentibacter, Proteiniborus, Ruminococcus and Lutispora were identified as potential PC producers in three media with glucose preferred as the carbon source. These findings provide a perspective on the microbiota and carbon source preference for ultimately improving the quality of distilled alcoholic beverage.

Selective carbon sources and salinities enhance enzymes and extracellular polymeric substances extrusion of Chlorella sp. for potential co-metabolism

This study investigated the extracellular polymeric substance (EPS) and enzyme extrusion of Chlorella sp. using seven carbon sources and two salinities for potential pollutant co-metabolism. Results indicated that the levels of biomass, EPS and enzymes of microalgae cultured with glucose and saccharose outcompeted other carbon sources. For pigment production, glycine received the highest chlorophyll and carotene, up to 10mg/L. The EPS reached 30mg/L, having doubled the amount of protein than carbohydrate. For superoxide dismutase and peroxidase enzymes, the highest concentrations were beyond 60U/ml and 6nmol/d.ml, respectively. This amount could be potentially used for degrading 40% ciprofloxacin of concentration 2000µg/L. When increasing salinity from 0.1% to 3.5%, the concentrations of pigment, EPS and enzymes rose 3 to 30 times. These results highlighted that certain carbon sources and salinities could induce Chlorella sp. to produce EPS and enzymes for pollutant co-metabolism and also for revenue-raising potential.

Individual and combined supplementation of carbon sources for growth augmentation and enrichment of lipids in the green microalga Tetradesmus obliquus

Microalgae with high lipid productivity offer great promise as a potential source of biodiesel, an alternative to fossil diesel. Since a target of both high biomass yield and lipid content is difficult to attain with the classical photoautotrophic mode of nutrition, mixotrophy has evolved as a preferred mode for enhancement of growth in microalgae. In the present study, this strategy was explored extensively with six different exogenous carbon sources in eight different concentrations to investigate the effect of these carbon sources on the biomass and lipid production potential of the green alga Tetradesmus obliquus (SAG 276-3a). To further augment the effect of mixotrophy on the growth and lipid accumulation of the test microalga, selected carbon sources with their specific concentrations showing enhancement in both biomass yield and lipid accumulation in the first phase of the experiment were interacted with each other. Significant rise in biomass yield by twofold was seen in the case of 0.16% citrate + 0.08% bicarbonate interaction, whereas for lipid accumulation, maximum rise in lipid content (% dry cell wt.) by 2.3-fold and lipid yield (g L-1) by 4.5-fold was observed in the case of 0.16% acetate + 0.16% citrate-supplemented cultures. The biodiesel samples as analyzed using GC–MS were predominated with saturated and monounsaturated fatty acid methyl esters. Fuel property analysis of the biodiesel samples found them to be well suited to the Indian, American (ASTM), and European (EN) biodiesel standards.

Long-chain vitamin K2 production in Lactococcus lactis is influenced by temperature, carbon source, aeration and mode of energy metabolism

BackgroundVitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Notably, long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products.ResultsWe observed that six selected Lactococcus lactis strains produced MK-5 to MK-10, with MK-8 and MK-9 as the major MK variant. Significant diversities between strains were observed in terms of specific concentrations and titres of vitamin K2. L. lactis ssp. cremoris MG1363 was selected for more detailed studies of the impact of selected carbon sources tested under different growth conditions [i.e. static fermentation (oxygen absent, heme absent); aerobic fermentation (oxygen present, heme absent) and aerobic respiration (oxygen present, heme present)] on vitamin K2 production in M17 media. Aerobic fermentation with fructose as a carbon source resulted in the highest specific concentration of vitamin K2: 3.7-fold increase compared to static fermentation with glucose, whereas aerobic respiration with trehalose resulted in the highest titre: 5.2-fold increase compared to static fermentation with glucose. When the same strain was applied to quark fermentation, we consistently observed that altered carbon source (fructose) and aerobic cultivation of the pre-culture resulted in efficient vitamin K2 fortification in the quark product.ConclusionsWith this study we demonstrate that certain LAB strains can be employed for efficient production of long-chain vitamin K2. Strain selection and optimisation of growth conditions offer a viable strategy towards natural vitamin K2 enrichment of fermented foods, and to improved biotechnological vitamin K2 production processes.

The contribution of selected organic substrates to the anaerobic cometabolism of sulfamethazine

Biodegradation of organic micropollutants is likely to occur due to cometabolism by particular microbial groups. In an effort to identify the stages of anaerobic digestion potentially involved in the biodegradation of the veterinary antimicrobial sulfamethazine (SMZ), the influence of selected carbon sources (sucrose, glucose, fructose, ethanol, meat extract, cellulose, soluble starch, soy oil, acetic acid, propionic acid and butyric acid) on SMZ removal by anaerobic sludge was evaluated in short-term batch experiments. Adsorption to the granular sludge constituted a significant removal mechanism, accounting for 39% of SMZ removal in control experiments. The presence of glucose, fructose, sucrose and meat extract exerted an inducing effect on SMZ degradation, resulting in removal efficiencies of 54, 53, 58 and 61%, respectively, indicating the occurrence of cometabolism. Time courses of sucrose and meat extract degradation revealed markedly distinct organic acid profiles but resulted in similar SMZ removals. Temporal profiles of acetic and propionic acid degradation were not associated with SMZ removal, as changes in SMZ concentration were observed even after the organic acids had been completely removed. The experimental results suggest that SMZ cometabolism is not associated to sucrose hydrolysis, acetoclastic methanogenesis and acetogenesis from propionic acid.

Growth and lovastatin production by Aspergillus terreus under different carbohyrates as carbon sources

Carbon source is a key component of metabolites synthesis in microorganisms. This work examined the effects of selected carbon sources in the form of carbohydrates, on the growth of Aspergillus terreus ATCC 20542 and the production of lovastatin. Slowly metabolised carbohydrates, such as D-galactose (consumption rate, r=3.11), produced a high microbial biomass, XFINAL (9.44 g/L) compared to other carbohydrates, but with a low biomass yield coefficient (YLOV/X=1.68). In contrast, D-ribose (YLOV/X=) which showed moderate biomass growth (XFINAL=8.78 g/L) and consumption rate (r=5.44 g/day), produced the highest lovastatin amount (51.81 mg/L, day 6). These indicate little correlation between biomass growth and lovastatin production. Notably, culture consisting of pellets with short hairy surface feature is associated with enhanced lovastatin production. Our findings suggest that the production of lovastatin by Aspergillus terreus is highly influenced by the choice of carbohydrates that will shape the pellet morphology rather than the rate of carbohydrates metabolism.

Employing Central Composite Design for Evaluation of Biomass Production by Fusarium venenatum: In Vivo Antioxidant and Antihyperlipidemic Properties.

The present study deals with the cost effective production of biomass from Fusarium venenatum using different carbon sources (cane sugar, brown sugar, malt and fructose). Optimization of selected carbon sources and seed size using Central Composite Response Surface Design (CCRSD) indicated that sucrose (1.64g/100mL) and seed size (10% v/v) were optimal in maximizing biomass yield (0.5602g/100mL, p<0.0001) and protein yield (49.99%, p<0.01) of Fusarium venenatum. The acetonitrile and methanolic extracts of biomass showed promising antioxidant activity (DPPH assay, 59.7 and 51.9% respectively, 250μg/mL). The mycoprotein, in the Triton-X 100-induced hyperlipidemic model in rats, exhibited significant reduction of serum lipids levels (p<0.01 at 100, 200 and 400mg/kg body weight) with significant increase in HDL level. It also exhibited antibacterial activity against S. aureus. LC-MS analysis of ACN extract of biomass showed two major peaks (Compound 3: m/e 701.4941 and Compound 2: m/e 651.4984). Spectral matching with standard MS libraries indicated that compound 3 may be structurally similar to sterol glycoside (m/e 716.99) with absence of methyl group. Also, compound 2 may be cholest-5-en-3-ol (3β)-, 9-octadecenoate. These results showed that Fusarium venenatum can act as a source of natural antioxidant along with acting as a valuable protein source. It may also prove to be beneficial in treatment of hyperlipidemia and other cardiovascular conditions. Further bioactivity-guided fractionation and isolation will help to obtain bioactives that may serve as leads for design of new class of therapeutic agents.

The exopolysaccharides biosynthesis by Candida yeast depends on carbon sources

Background: The exopolysaccharides (EPS) produced by yeast exhibit physico-chemical and rheological properties, which are useful in the production of food and in the cosmetic and pharmaceutical industries as well. The effect was investigated of selected carbon sources on the biosynthesis of EPS by Candida famata and Candida guilliermondii strains originally isolated from kefirs. Results: The biomass yields were dependent on carbon source (sucrose, maltose, lactose, glycerol, sorbitol) and ranged from 4.13 to 7.15 g/L. The highest biomass yield was reported for C. guilliermondii after cultivation on maltose. The maximum specific productivity of EPS during cultivation on maltose was 0.505 and 0.321 for C. guilliermondii and C. famata , respectively. The highest EPS yield was found for C. guilliermondii strain. The EPS produced under these conditions contained 65.4% and 61.5% carbohydrates, respectively. The specific growth rate ( μ ) of C. famata in medium containing EPS as a sole carbon source was 0.0068 h -1 and 0.0138 h -1 for C. guilliermondii strain. Conclusions: The most preferred carbon source in the synthesis of EPS for both Candida strains was maltose, wherein C. guilliermondii strain showed the higher yield of EPS biosynthesis. The carbon source affected the chemical composition of the resulting EPS and the contribution of carbohydrate in the precipitated preparation of polymers was higher during supplementation of maltose as compared to sucrose. It was also found that the EPS can be a source of carbon for the producing strains.

Enhanced Endoglucanase Production by Bacillus aerius on Mixed Lignocellulosic Substrates

Selected carbon sources including soluble carboxymethyl cellulose (CMC), insoluble microcrystalline cellulose (MCC), and single (SS)/mixed lignocellulosic substrates (MS), were evaluated for endoglucanase production by B. aerius S5.2. The lignocellulosic substrates of oil palm empty fruit bunch (EFB), oil palm frond (OPF), rice husk (RH), and their mixture (MS) supported growth of the strain better than CMC and MCC. The maximum endoglucanase activity on MS was 7.3-, 2.6-, 1.7-, and 1.2-fold higher than those recorded on MCC, CMC, EFB/OPF, and RH, respectively. While the reducing sugar concentration of the CMC medium was comparable to that of the EFB and MS media, wide variability was observed in the reducing sugar concentrations among the lignocellulosic substrates. Extremely low levels of sugar were detected in the MCC medium, reflecting its poor digestibility and hence unsuitability for growth and endoglucanase production. Endoglucanase production was predominantly extracellular when the strain was grown on CMC and MS. After seven days of fermentation, there was an approximately 25% reduction in MS dry weight. These findings show that the use of mixed lignocellulosics could potentially reduce the cost of cellulase production. Certain novel aspects of the cellulase system of B. aerius are reported in this study.

An organic solvent-stable lipase from a newly isolated Staphylococcus aureus ALA1 strain with potential for use as an industrial biocatalyst.

In this study, a new strain, ALA1, was identified as Staphylococcus aureus by biochemical tests, and its 16S ribosomal DNA sequence was isolated from dromedary milk. ALA1 lipase production was optimized in shake flask experiments and measured with varying pH (3-11), temperature (20-55°C) and substrate concentrations. The maximum lipase production was recorded at pH 8 and 30°C for up to 30H of culture period for the S. aureus ALA1 strain. Among the substrates tested, selected carbon sources, xylose, nitrogen source, yeast extract, and olive oil (1%) were suitable for maximizing lipase production. The effects of surfactants were investigated and showed that Tween 20, Tween 80, and Triton X-100 prevented lipase production. Interestingly, isolate ALA1 was able to grow in high concentrations of benzene or toluene (up to 50% (v/v)). Moreover, the lipolytic activity of the S. aureus ALA1 lipase was stimulated by diethyl ether, whereas almost 100% of S. aureus ALA1 lipase activity was retained in 25% acetone, acetonitrile, benzene, 2-propanol, ethanol, methanol, or toluene. Because of its stability in organic solvent, the S. aureus ALA1 lipase was used as a biocatalyst to synthesize high levels of added value molecules. S. aureus ALA1 lipase could be considered as an ideal choice for applications in detergent formulations because of its high stability and compatibility with various surfactants, oxidizing agents, and commercial detergents.

Carbohydrate-active enzymes in pythium and their role in plant cell wall and storage polysaccharide degradation.

Carbohydrate-active enzymes (CAZymes) are involved in the metabolism of glycoconjugates, oligosaccharides, and polysaccharides and, in the case of plant pathogens, in the degradation of the host cell wall and storage compounds. We performed an in silico analysis of CAZymes predicted from the genomes of seven Pythium species (Py. aphanidermatum, Py. arrhenomanes, Py. irregulare, Py. iwayamai, Py. ultimum var. ultimum, Py. ultimum var. sporangiiferum and Py. vexans) using the “CAZymes Analysis Toolkit” and “Database for Automated Carbohydrate-active Enzyme Annotation” and compared them to previously published oomycete genomes. Growth of Pythium spp. was assessed in a minimal medium containing selected carbon sources that are usually present in plants. The in silico analyses, coupled with our in vitro growth assays, suggest that most of the predicted CAZymes are involved in the metabolism of the oomycete cell wall with starch and sucrose serving as the main carbohydrate sources for growth of these plant pathogens. The genomes of Pythium spp. also encode pectinases and cellulases that facilitate degradation of the plant cell wall and are important in hyphal penetration; however, the species examined in this study lack the requisite genes for the complete saccharification of these carbohydrates for use as a carbon source. Genes encoding for xylan, xyloglucan, (galacto)(gluco)mannan and cutin degradation were absent or infrequent in Pythium spp.. Comparative analyses of predicted CAZymes in oomycetes indicated distinct evolutionary histories. Furthermore, CAZyme gene families among Pythium spp. were not uniformly distributed in the genomes, suggesting independent gene loss events, reflective of the polyphyletic relationships among some of the species.