Production of polyhydroxyalkanoates from whey by Thermus thermophilus HB8

The thermophilic bacterium Thermus thermophilus HB8 is able to utilize lactose from whey-based media for the biosynthesis of polyhydroxyalkanoates (PHAs) under nitrogen limitation. T. thermophilus can utilize both, glucose and galactose, the products of lactose hydrolysis. When T. thermophilus HB8 was grown in culture media containing 24% (v/v) whey, PHA was accumulated up to 35% (w/w) of its biomass after 24 h of cultivation. The effect of initial phosphate concentration on the PHA production was also investigated. Using an initial phosphate concentration of 50 mM the PHA accumulation was enhanced. Analysis of the produced PHA from T. thermophilous HB8 grown in whey-based media revealed a novel heteropolymer consisting of the short chain length 3-hydroxyvalerate (3HV; 38 mol%) and the medium chain length, 3-hydroxyheptanoate (3HHp; 9.89 mol%), 3-hydroxynanoate (3HN; 16.59 mol%) and 3-hydroxyundecanoate (3HU; 35.42 mol%). Despite the low molecular weight of the produced PHA by T. thermophilus, whey could be an excellent substrate for the production of heteropolymers with unique properties.     

Correlation of ovary and leaf spermidine and spermine content with the alternate bearing habit of olive

In order to investigate the possible role of the polyamines spermidine and spermine, in the alternate bearing habit of the olive, a comparative analysis of their content in vegetative and reproductive organs during the flowering period of the 'on' and 'off' years, was conducted. Samples of flowers, ovaries and leaves from two cultivars, the biennial bearer 'Chondrolia Chalkidikis' and the regular cropping 'Koroneiki' were used and the free and conjugated forms of polyamines were detected. In addition, the concentrations of K(+) and Ca(2+) were determined in all samples. Spermidine conjugates were predominant in all samples, while free spermine was not detectable. Conjugated forms of both spermidine and spermine were accumulated in ovaries, rather than in other floral tissues (corolla and stamens). They also, accumulated in significantly higher concentrations in ovaries and leaves of both cultivars, during the 'on' compared with the 'off' year, and in much higher concentrations, during the 'on' year, in ovaries of the strong alternate bearer 'Chondrolia Chalkidikis' than in 'Koroneiki'. Free spermidine was detected in ovaries and leaves of both cultivars, showing a decline during ovule fertilization in both years. Such a decline was not always recorded for the conjugated forms, depending on the organ studied and the flower load. A relation between endogenous spermidine and spermine with the K(+) or Ca(2+) composition was not established.     

Leaf Physiological Traits and their Importance for Species Success in a Mediterranean Grassland

We related leaf physiological traits of four grassland species (Poa pratensis, Lolium perenne, Festuca valida, and Taraxacum officinale), dominant in a Mediterranean grassland, to their origin and success at community level. From early May to mid-June 1999, four leaf samplings were done. Species originating from poor environments (P. pratensis, F. valida) had low carbon isotope discrimination (), specific leaf area (SLA), leaf water and mineral contents, and net photosynthetic rate on mass basis (P _mass) but high chlorophyll content. The reverse traits were evident for the fast-growing species (L. perenne, T. officinale). Under the resource-limiting conditions (soil nitrogen and water) of the Mediterranean grassland, the physiological traits of P. pratensis and F. valida showed to be more adapted to these conditions leading to high species abundance and dominance.     

Sunflower seed oil and oleic acid utilization for the production of rhamnolipids by Thermus thermophilus HB8

The potential production of rhamnolipids was demonstrated using the thermophilic eubacterium Thermus thermophilus HB8 and sunflower seed oil or oleic acid as carbon sources. Sunflower seed oil was directly hydrolyzed by secretion of lipase and became a favorable carbon source for rhamnolipids production. Rhamnolipids levels were attainted high values, comparable to those produced by Pseudomonas strains from similar sources. Rhamnolipids synthesis in oleic acid exhibited a long period of induction, while in sunflower seed oil, the synthesis is more rapid. Glucose resulted in a more protracted period of rhamnolipids production after exhaustion of each or both carbon sources. Both mono- and di-rhamnolipids were identified by thin-layer chromatography (TLC) in the total rhamnolipids extract. The molecular composition of the produced biosurfactant was evaluated by Fourier transform infrared (FTIR) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and LC-MS analysis. Furthermore, secretion of rhamnolipids was confirmed on agar plates. The antimicrobial activity of rhamnolipids was detected against the bacterium Micrococcus lysodeikticus using a lysoplate assay. These results demonstrate that rhamnolipids produced in these substrates can be useful in both environmental and food industry applications by using cheap oil wastes. The alternative use of this thermophilic microorganism opens a new perspective concerning the valorization of wastes containing plant oils or frying oils to reduce the cost of rhamnolipids production.     

L-asparaginase of Thermus thermophilus: Purification,properties and identificaation of essential amino acids for its catalytic activity

L-asparaginase EC 3.5.1.1 was purified to homogeneity from Thermus thermophilus. The apparent molecular mass of L-asparaginase by SDS-PAGE was found to be 33 kDa, whereas by its mobility on Sephacryl S-300 superfine column was around 200 kDa, indicating that the enzyme at the native stage acts as hexamer. The purified enzyme showed a single band on acrylamide gel electrophoresis with pI = 6.0. The optimum pH was 9.2 and the Km for L-asparagine was 2.8 mM. It is a thermostable enzyme and it follows linear kinetics even at 77°C. Chemical modification experiments implied the existence of histidyl, arginyl and a carboxylic residues located at or near active site while serine and mainly cysteine seems to be necessary for active form.     

Biotechnologically relevant enzymes from Thermus thermophilus

. Enzymes produced by Thermus thermophilus are of considerable biotechnological interest. This review covers industrial applications of several protein products of this thermophilic bacterium that are functional under extreme conditions. The purification of proteins from T. thermophilus using either conventional methods or in the light of the cloning of their genes and expression in mesophilic microorganisms is discussed. Enzymes that biodegrade proteins, polysaccharides or key enzymes that are involved in amino acid metabolism, protein folding or in other fundamental biological processes such as DNA replication, DNA repair, and RNA maturation, with potential use in different biotechnological processes are reviewed as well.     

A pilot study on the prevalence of maternal obesity in selected Greek counties

ObjectiveTo report a pilot prevalence of maternal overweight, obesity and underweight in selected Greek counties.MethodsA total of 441 adult childbearing women were recruited from maternity clinics in 6 Greek counties for this cross-sectional study. Pre-gravid weight status was defined according to the WHO cut-offs and gravid weight status was diagnosed with the Mardones and Rosso weight gain chart.ResultsDuring gestation the majority of the participants were of normal body weight (BW) (34.0%), obesity was apparent in 25.6% of the sample, 23.8% of the participants were underweight, and the remaining 16.6% were overweight. Overall, pregnancy tripled the prevalence of underweight, increased the prevalence of obesity (by 388.0%) and decreased the number of participants in the normal BW category (p ≤ 0.001 for all). The majority of participants classified in each pre-gravid weight-category remained in the same weight category during their gestation. All the pre-gravidly obese women were also obese during pregnancy. Underweight was more prevalent in Kavala (37.5%) and obesity was more frequent in Thessaloniki (30.8%). Women who were overweight prior to conception were highly likely to be overweight/obese during pregnancy (OR: 23.8, CI: 11.1–51.0).ConclusionsThe results indicate a high prevalence of overweight, obesity and underweight among pregnant women in Greece.