Thermotropic behavior of lipids and the morphology of <Emphasis Type="Italic">Yersinia pseudotuberculosis</Emphasis> cells with a high content of lysophosphatidylethanolamine

The content of lysophosphatidylethanolamine (LPE) in Y. pseudotuberculosis cells was found to increase during their growth at 8 °C under stationary conditions (without stirring the medium) and at 37°C when the medium contained glucose. The maximum level of LPE (up to 45% of the total phospholipids) was observed in cells grown at 8°C under stationary conditions. Such cells showed decreas growth rate, a reduced yield of biomass, an altered cell morphology, and an increased cell area. The cells contained unsaturated fatty acids, phosphatidylethanolamine (PE), and total phospholipids in small amounts, whereas neutral lipids and diphosphatidylglycerol were abundant. In addition, the cells contained an amount of methylated PE and phospholipids of unknown structure. Irrespective of whether the temperature for growth was low or high, the LPE-rich cells showed a high value (32–36°C) of the maximum temperature of thermal transition of lipids (T _max). This finding is indicative of a densification of the membrane lipid matrix of the LPE-rich cells. The suggestion is made that LPE is accumulated in bacterial cells in response to stress caused by oxygen deficiency and pH decrease in the course of glucose fermentatin. The possible relationship between LPE accumulation and the virulence of Y. pseudotuberculosis cells grown at low temperatures is discussed.     

Effects of 20 Standard Amino Acids on the Growth,Total Fatty Acids Production,and γ-Linolenic Acid Yield in Mucor circinelloides

Twenty standard amino acids were examined as single nitrogen source on the growth, total fatty acids production, and yield of γ-linolenic acid (GLA) in Mucor circinelloides. Of the amino acids, tyrosine gave the highest biomass and lipid accumulation and thus resulted in a high GLA yield with respective values of 17.8 g/L, 23 % (w/w, dry cell weight, DCW), and 0.81 g/L, which were 36, 25, and 72 % higher than when the fungus was grown with ammonium tartrate. To find out the potential mechanism underlying the increased lipid accumulation of M. circinelloides when grown on tyrosine, the activity of lipogenic enzymes of the fungus during lipid accumulation phase was measured. The enzyme activities of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and ATP-citrate lyase were up-regulated, while NADP-isocitrate dehydrogenase was down-regulated by tyrosine during the lipid accumulation phase of the fungus which suggested that these enzymes may be involved in the increased lipid biosynthesis by tyrosine in this fungus.     

Secretome profiling reveals temperature-dependent growth of <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis>

Aspergillus fumigatus is a ubiquitous opportunistic fungus. In this study, systematic analyses were carried out to study the temperature adaptability of A. fumigatus. A total of 241 glycoside hydrolases and 69 proteases in the secretome revealed the strong capability of A. fumigatus to degrade plant biomass and protein substrates. In total, 129 pathogenesis-related proteins detected in the secretome were strongly correlated with glycoside hydrolases and proteases. The variety and abundance of proteins remained at temperatures of 34°C–45°C. The percentage of endo-1,4-xylanase increased when the temperature was lowered to 20°C, while the percentage of cellobiohydrolase increased as temperature was increased, suggesting that the strain obtains carbon mainly by degrading xylan and cellulose, and the main types of proteases in the secretome were aminopeptidases and carboxypeptidases. Only half of the proteins were retained and their abundance declined to 9.7% at 55°C. The activities of the remaining β-glycosidases and proteases were merely 35% and 24%, respectively, when the secretome was treated at 60°C for 2 h. Therefore, temperatures >60°C restrict the growth of A. fumigatus.     

Lipid production by microalgae <Emphasis Type="Italic">Chlorella protothecoides</Emphasis> with volatile fatty acids (VFAs) as carbon sources in heterotrophic cultivation and its economic assessment

Volatile fatty acids (VFAs) that can be derived from food wastes were used for microbial lipid production by Chlorella protothecoides in heterotrophic cultures. The usage of VFAs as carbon sources for lipid accumulation was investigated in batch cultures. Culture medium, culture temperature, and nitrogen sources were explored for lipid production in the heterotrophic cultivation. The concentration and the ratio of VFAs exhibited significant influence on cell growth and lipid accumulation. The highest lipid yield coefficient and lipid content of C. protothecoides grown on VFAs were 0.187 g/g and 48.7 %, respectively. The lipid content and fatty acids produced using VFAs as carbon sources were similar to those seen on growth and production using glucose. The techno-economic analysis indicates that the biodiesel derived from the lipids produced by heterotrophic C. protothecoides with VFAs as carbon sources is very promising and competitive with other biofuels and fossil fuels.     

Improvement of lipid production from an oil-producing filamentous fungus, <Emphasis Type="Italic">Penicillium brevicompactum</Emphasis> NRC 829, through central composite statistical design

In the present study, 13 filamentous fungi were screened for their lipid production and an oleaginous fungus, Penicillium brevicompactum NRC 829, was found to be the highest lipid producer. Screening of various agro-industrial residues was performed and sunflower oil cake proved to be the best substrate for lipid production. A central composite design was employed to investigate the optimum concentrations of the most significant medium components required to improve the lipid production by P. brevicompactum. The results clearly revealed that the maximal lipid production of 8.014 ± 0.06 gL^?1 (representing 57.6% lipid/dry biomass) was achieved by the fungus when grown for 6 days at 30 °C under static condition in a medium containing sunflower oil cake, NaNO₃ and KCl at final concentrations of 8, 0.75 and 0.25 gL^?1, respectively. Gas chromatography-mass spectrometry analysis of P. brevicompactum lipid indicated that linoleic acid (LA) (C18:2–6, 9) was the most abundant fatty acid, accounting for up to 62% of the total fatty acid profile, followed by palmitoleic acid (C16:1, 16%) and linolenic acid (C18:3, 8%). These results suggest that P. brevicompactum NRC 829 may have potential for commercial development for the production of LA by fermentation using cheap raw material.     

Genome sequence of <Emphasis Type="Italic">Candida versatilis</Emphasis> and comparative analysis with other yeast

The genome of Candida versatilis was sequenced to understand its characteristics in soy sauce fermentation. The genome size of C. versatilis was 9.7 Mb, the content of G + C was 39.74 %, scaffolds of N50 were 1,229,640 bp in length, containing 4711 gene. There were predicted 269 tRNA genes and 2201 proteins with clear function. Moreover, the genome information of C. versatilis was compared with another salt-tolerant yeast Zygosaccharomyces rouxii and the model organism Saccharomyces cerevisiae. C. versatilis and Z. rouxii genome size was close and both smaller than 12.1 for the Mb of S. cerevisiae. Using the OrthoMCL protein, three genomes were divided into 4663 groups. There were about 3326 homologous proteins in C. versatilis, Z. rouxii and S. cerevisiae.     

Preliminary study on bioethanol from fresh water algae, <Emphasis Type="Italic">Cladophora glomerata</Emphasis> (Sarai Kai) by the fungus, <Emphasis Type="Italic">Monascus</Emphasis> sp. NP1

This work focused on the characteristics of ethanol regulation from Monascus sp. NP1. in glucose liquid medium, a saccharification method using algae and bioethanol production from Cladophora glomerata by the fungus. The results showed that when the fungus was grown in glucose (2, 20, 40 and 50%) medium under 110 rpm rotary culture at 30 °C, the ethanol concentration at 120 h increased from 2 to 20% glucose, where it peaked. It then decreased gradually to 40%, with production stopping at 50% glucose. This result indicated the glucose regulation of ethanol production by the fungus. Ethanol present in 20% glucose medium was identified by retention time and co-injection with a standard to demonstrate that the product was ethanol. Its yield was 285 mM [13 g L^?1 or 65 mg (g of glucose substrate)^?1] with a low interference of by-products. Three-millimetre-long pieces of dried algae were cut and exposed to concentrations of 1, 2, 3, 4, 5 and 6 g in 65 mL of 0.3 N hydrochloric acid or sulfuric acid before autoclaving (121 °C, 15 psi, 15 min). The amount of reducing sugar was greater than that of the control (without acid treatment) and varied with the increasing quantity of algae. The best condition was sulfuric acid and 6 g dried algae. The type of acid appeared to affect saccharification. During 12 days of fermentation in algal extraction (2 g reducing sugar per millilitre algal extraction), the mould could produce twofold more ethanol yield [34–55 mg (100 g dried weight algae)^?1] than the yeast, Saccharomyces cerevisiae TISTR 5049.     

Endocellulase Production by <Emphasis Type="Italic">Cotylidia pannosa</Emphasis> and its Application in Saccharification of Wheat Bran to Bioethanol

For efficient bioconversion of lignocellulosic materials to bioethanol, the study screened 19 white-rot fungal strains for their endocellulolytic activity and saccharification potential. Preliminary qualitative and quantitative screening revealed Cotylidia pannosa to be the most efficient endocellulase producing fungal strain when compared to the standard strain of Trichoderma reesei MTCC 164. Ensuing initial screening, the production of endocellulase was further optimized using submerged fermentation to recognize process parameters such as temperature, time, agitation pH, and supplementation of salts in media required for achieving maximum production of endocellulase. The strain C. pannosa produced the maximum amount of endocellulase (8.48 U/mL) under submerged fermentation with wheat bran (2%) supplemented yeast extract peptone dextrose (YEPD) medium after an incubation time of 56 h at 30 °C and pH 5.0 at an agitation rate of 120 rpm with a saccharification value of 50.5%. The fermentation of wheat bran hydrolysate with Saccharomyces cerevisiae MTCC 174 produced 4.12 g/L of bioethanol after 56 h of incubation at 30 °C. The results obtained from the present investigation establish the potential of white-rot fungus C. pannosa for hydrolysis and saccharification of wheat bran to yield fermentable sugars for their subsequent conversion to bioethanol, suggesting its application in efficient bioprocessing of lignocellulosic wastes.     

High temperature enhances lipid accumulation in nitrogen-deprived <Emphasis Type="Italic">Scenedesmus obtusus</Emphasis> XJ-15

This study investigated the changes in lipid and starch contents, lipid fraction, and lipid profile in the nitrogen-starved Scenedesmus obtusus XJ-15 at different temperatures (17, 25, and 33 °C). The optimal temperature for both growth and lipid accumulation under nitrogen-sufficient condition was found to be 25 °C. However, under nitrogen deprivation, the total and neutral lipids increased with increasing temperature, and achieved the highest lipid content of 47.60 % of dry cell weight and the highest TAG content of 79.66 % of total lipid at 33 °C. In the meantime, the stored cellular starch content decreased with the increasing temperature. Thus, high temperature induced carbon flux from starch toward TAG accumulation in microalgae during nitrogen starvation. In addition, the decreased polar lipids may also serve for TAG synthesis under high temperature, and high temperature further reduced the degree of the fatty acid unsaturation and favored a better biodiesel production. These results suggested that high-temperature stress can be a good strategy for enhancing biofuel production in oleaginous microalgae during nitrogen deficiency.     

Optimization of environmental parameters for <Emphasis Type="Italic">Nannochloropsis salina</Emphasis> growth and lipid content using the response surface method and invading organisms

Algae biofuel has the potential to replace fossil fuels. However, cultivation and productivity of target algae need improvement, while controlling undesired organisms that can lower the efficiency of production systems. A central composite design and response surface model were utilized to predict cultivation optima of marine microalga, Nannochloropsis salina, under a suite of environmental parameters. The effects of salinity, pH, and temperature and their interactions were studied on maximum sustainable yield (MSY, a measure for biomass productivity), lipid content of N. salina, and invading organisms. Five different levels of each environmental predictor variable were tested. The environmental factors were kept within ranges that had previously been determined to allow positive N. salina growth (14.5–45.5 PSU; pH 6.3–9.7; 11–29 °C). The models created for this experiment showed that N. salina’s MSY and lipid content are not strongly affected over the broad range of salinity and temperature values. Calculated optima levels were 28 PSU/20 °C for MSY and 14.5 PSU/20 °C for lipid accumulation, but neither value significantly influenced the model. However, pH was the most important factor to influence algae productivity, and pH optimum was estimated around 8. Both MSY and lipid content were strongly reduced when pH deviated from the optimum. Occurrence of invading organisms seemed stochastic, and none of the environmental factors studied significantly influenced abundance. In conclusion, pH should be kept around 8 for maximum productivity of N. salina. Temperature and salinity should be kept around 20 °C and 28 PSU; however, moderate variations are not too much of a concern and might enhance lipid content of N. salina.     

Heterologous expression and characterization of a novel halotolerant,thermostable, and alkali-stable GH6 endoglucanase from <Emphasis Type="Italic">Thermobifida halotolerans</Emphasis>

A novel endoglucanase gene was cloned from Thermobifida halotolerans YIM 90462^T, designated as thcel6A for being a member of glycoside hydrolase family 6. The gene was 1332 bp long and encoded a 443-amino-acid protein with a molecular mass of 45.9 kDa. The purified recombinant endoglucanase had optimal activity at 55 °C and pH 8.5. Thcel6A showed high hydrolytic activities at 25–55 °C and retained 58 % of initial activity after incubation at 90 °C for 1 h. It retained more than 80 % of activity after incubation for 12 h at pH values from 4 to 12. Thcel6A displayed higher hydrolytic activities in 5–15 % NaCl (w/v) than at 0 % NaCl. Activity increased 2.5-fold after incubation with 20 % (w/v) NaCl at 37 °C for 10 min. These properties suggest that this novel endoglucanase has potential for specific industrial application.     

Effect of Temperature on the Morphometrical and Physical Parameters of Erythrocytes and Polymorphonuclear Leucocytes in <Emphasis Type="Italic">Carassius gibelio</Emphasis> (Bloch)

Dynamics of the morphometric and physical properties of hemocytes of the Prussian carp Carassius gibelio (Bloch) under the influence of a temperature factor has been studied with atomic force microscopy in experiments in vitro. It is found that, at a low incubation temperature (5°C), as opposed to room temperature (20°C), morphometric parameters change in erythrocytes; at a high temperature (40°C) they change in polymorphonuclear leucocytes. The low incubation temperature reduces the adhesion and elasticity of polymorphonuclear leucocytes and erythrocytes of C. gibelio, whereas a high incubation temperature leads to a decrease in adhesion in polymorphonuclear white blood cells.     

Effect of growth temperature on the composition of phenols in pea roots

It was shown that, in pea (Pisum sativum L.) roots, flavans are a dominating component of the soluble phenol fraction. In plants grown at low temperature (8°C), flavan content during the early growth phase was lower than in plants grown at 22°C, but later it increased and was by 40% higher than in plants grown at 22°C. Total phenol content in the two treatments differed insignificantly. Low growth temperature decreased the content of some phenolic compounds in pea seedling roots.     

Growth and palmitoleic acid accumulation of filamentous oleaginous microalgae <Emphasis Type="Italic">Tribonema minus</Emphasis> at varying temperatures and light regimes

Palmitoleic acid (C16:1Δ9), contributes greatly to human health, industrial chemicals and biodiesel. The filamentous oleaginous microalgae Tribonema sp. has been identified as a highly efficient producer of palmitoleic acid. Temperature and light regime were adapted to regulate the palmitoleic acid content in this study. Strain T. minus was able to grow well at all the tested temperatures, even at 5 °C. The optimum temperature for palmitoleic acid accumulation (54.25 % of total fatty acid) was 25 °C. Moreover, both light intensity and photoperiod affect the growth, lipid content and fatty acid files of T. minus. The culture exposed to 240 μmol photons m^?2 s^?1 with a photoperiod of 24:0 showed the highest biomass (6.87 g L^?1) and biggest lipid content (61.27 % of dry weight), whereas the most amount of palmitoleic acid (50.47 % of total fatty acid) was detected at 120 μmol photons m^?2 s^?1. These findings make tangible contributions to culture T. minus for commercial production of lipid or palmitoleic acid.     

Metabolic characteristics and lipid composition of yeastlike cells and mycelium of <Emphasis Type="Italic">Mucor circinelloides</Emphasis> var. <Emphasis Type="Italic">lusitanicus</Emphasis> INMI grown at a high glucose content in the medium

It is shown that the fungus Mucor circinelloides var. lusitanicus INMI grown under aerobic conditions in a medium with a high glucose concentration (20%) is capable of both yeastlike and mycelial growth. In the mycelium, the activity of NAD-dependent isocitrate dehydrogenase was more than twice as high as in yeastlike cells, whereas the isocitrate lyase activity was lower. A number of significant differences were found in the lipid composition of the cells of two different morphological variants. Yeastlike cells contained more polar lipids and free fatty acids and less principal reserve lipids (triacylglycerides) than mycelial cells; the content of γ-linolenic acid and the degree of lipid unsaturation were significantly lower in these cells than in the mycelium. In yeastlike cells, glycolipids composed the bulk of polar lipids; the proportion of phospholipids (primarily phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin) was lower. The relationship between cellular metabolism and the lipid composition of fungal cells of different morphotypes grown at high concentrations of glucose, one of the main inducers of dimorphic growth, is discussed.     

Production of gamma-linolenic acid by Mucor circinelloides and Mucor rouxii with acetic acid as carbon substrate

Summary The production of gamma-linolenic acid (GLA) by Mucor circinelloides CBS 203.28 and M. rouxii CBS 416.77 in fed-batch cultures operated in pH-stat mode with acetic acid as carbon substrate and titrant compared favourably with the performance of M. circinelloides in batch culture on glucose. On acetic acid M. circinelloides accumulated up to 39.8 mg GLA/g biomass, with a crude oil content of 28% containing 91% neutral lipids. The GLA content of the neutral lipid fraction was 15.6%.     

Rapid bioremediation of Alizarin Red S and Quinizarine Green SS dyes using <Emphasis Type="Italic">Trichoderma lixii</Emphasis> F21 mediated by biosorption and enzymatic processes

In this study, a newly isolated ascomycete fungus Trichoderma lixii F21 was explored to bioremediate the polar [Alizarin Red S (ARS)] and non-polar [Quinizarine Green SS (QGSS)] anthraquinone dyes. The bioremediation of ARS and QGSS by T. lixii F21 was found to be 77.78 and 98.31 %, respectively, via biosorption and enzymatic processes within 7 days of incubation. The maximum biosorption (ARS = 33.7 % and QGSS = 74.7 %) and enzymatic biodegradation (ARS = 44.1 % and QGSS = 23.6 %) were observed at pH 4 and 27 °C in the presence of glucose and yeast extract. The laccase and catechol 1,2-dioxygenase produced by T. lixii F21 were involved in the molecular conversions of ARS and QGSS to phenolic and carboxylic acid compounds, without the formation of toxic aromatic amines. This study suggests that T. lixii F21 may be a good candidate for the bioremediation of industrial effluents contaminated with anthraquinone dyes.     

Effects of heat stress on photosynthetic electron transport in a marine cyanobacterium <Emphasis Type="Italic">Arthrospira</Emphasis> sp.

Arthrospira (Spirulina) is widely used as human health food and animal feed. In cultures grown outdoors in open ponds, Arthrospira cells are subjected to various environmental stresses, such as high temperature. A better understanding of the effects of high temperature on photosynthesis may help optimize the productivity of Arthrospira cultures. In this study, the effects of heat stress on photosynthetic rate, chlorophyll a fluorescence transients, and photosystem (PS) II, PSI activities in a marine cyanobacterium Arthrospira sp. were examined. Arthrospira cells grown at 25 °C were treated for 30 min at 25 (control), 30, 34, 37, or 40 °C in the dark. Heat stress (30–37 °C) enhanced net photosynthetic O₂ evolution rate. Heat stress caused over-reduction PSII acceptor side, damage of donor side of PSII, decrease in the energetic connectivity of PSII units, and decrease in the performance of PSII. When the temperature changed from 25 to 37 °C, PSII activity decreased, while PSI activity increased, the enhancement of photosynthetic O₂ evolution was synchronized with the increase in PSI activity. When temperature was further increased to 40 °C, it induced a decrease in photosynthetic O₂ evolution rate and a more severe decrease in PSII activity, but an increase in PSI activity. These results suggest that PSI activity was the decisive factor determining the change of photosynthetic O₂ evolution when Arthrospira was exposed to a temperature from 25 to 37 °C, but then, PSII activity became the decisive factor adjusting the change of photosynthetic O₂ evolution when the temperature was increased to 40 °C.     

Competition between native Antarctic vascular plants and invasive <Emphasis Type="Italic">Poa annua</Emphasis> changes with temperature and soil nitrogen availability

Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5°/2° and 11°/5 °C (day/night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 µM of N. Overall, Poa exerted a competitive effect on Deschampsia but only at the higher temperature and higher N availability. At 5°/11 °C the competitive response of Deschampsia to Poa was of similar magnitude to the competitive effect of P. Deschampsia, and the competitive effect was greater with at low N. The competitive effect of Poa was similar to the competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming.