Kinetics of biosurfactant production by Pseudomonas aeruginosa strain BS2 from industrial wastes

Summary Batch kinetic studies were carried out on rhamnolipid biosurfactant production from synthetic medium, industrial wastes viz. distillery and whey waste as substrates. The results indicated that the specific growth rates ( _max) and specific product formation rates (V _max) from both the wastes are comparatively better than the synthetic medium, revealing that both the industrial wastes (distillery and whey) can be successfully utilized as substrates for biosurfactant production.     

Twin-core packed-bed reactors for organic-phase enzymatic esterification with water activity control

A method for the removal of water and the control of water activity, a _w, during enzymatic esterification is the use of salt hydrate pairs. When this technique is used on a laboratory scale, the recovery and reuse of the salt are not critical. Potential problems, such as the reactivity of some salts, can also be overcome simply by substituting another salt. However, if this technique is to be used on a larger scale, economic constraints would require salt recovery and restric the range of salts that could be used. In this article a twin-core packed-bed reactor — used for the esterification of an equimolar mixture of decanoic acid and dodecanol catalysed by lipase from Candida rugosa — which facilitates salt recovery and permits a _w control without direct contact between immobilized enzyme and salt, has been described. a _w control was maintained by using suitable salt hydrate mixtures in the inner core of the reactor. The substrate mixture was esterified by pumping it through the outer core of the reactor, which contained enzyme immobilized on a macroporous polypropylene support. Complete conversion, albeit at different rates, was obtained with a _w buffering at 0.48 and 0.8 by using hydrates of Na₄P₂O₇ and Na₂HPO₄.     

Identification,characterization, validation and cross-species amplification of genic-SSRs in Indian Mustard (<Emphasis Type="Italic">Brassica juncea</Emphasis>)

Brassica juncea is an economically important oilseed crop worldwide. It has limited genomic resources at present. We generated 47,962,057 expressed sequence reads which were assembled into 45,280 unigenes. A total of 4108 SSR loci (≥10 bp) were identified in these unigenes. Trinucleotide was the most frequent repeat unit (59.91 %) followed by di- (38.66 %), tetra - (0.71 %), hexa - (0.49 %) and pentanucleotide repeats (0.24 %). Primers were designed for 2863 SSR loci among which 460 were selected for primer synthesis. A total of 339 loci amplified successfully of which 134 (39.5 %) exhibited polymorphism among six B. juncea genotypes with PIC values ranging from 0.18 to 0.81. Further, 25 polymorphic SSRs were used for analysis of genetic variability in 25 genotypes of Brassicas and their wild relatives. Two to five alleles with PIC values 0.22–0.66 were detected at these loci. The dendrogram grouped the genotypes according to their known pedigree/systematic position.     

Effect of altered sterol levels on the transport of amino acids and membrane structure ofMicrosporum gypseum

Ergosterol and cholesterol supplementation resulted in a significant increase (1·5-fold) in the sterol content while phospholipid remained unaffected inMicrosporum gypseum. The levels of phosphatidylethanolamine and phosphatidylcholine increased in ergosterol supplemented cells. However, a decrease in phosphatidylcholine and an increase in phosphatidylethanolamine was observed in cholesterol grown cells. The ratio of unsaturated to saturated fatty acids decreased on ergosterol/cholesterol supplementation. The uptake of amino acids (lysine, glycine and aspartic acid) decreased in sterol supplemented cells. Studies with fluorescent probe l-anilinonaphthalene-8-sulfonate showed structural changes in membrane organisation as evident by increased number of binding sites in such cells.     

Long-term effects of ungulates on phytophagous insects

Abstract.  1. Most plants interact with a diverse suite of herbivores, allowing the opportunity for the existence of positive and negative interactions between highly dissimilar organisms. However, most studies on herbivorous interactions have been performed under the assumption that they occur mainly between similar species. Consequently, ecologists are still far from a full understanding of the ecological factors that determine insect population dynamics.
2. In this study, a 7-year field experiment was conducted that manipulated the presence of ungulates to evaluate their effects on the abundance, attack rate, and survival of four guilds of co-occurring herbivorous insects living on the same host plant: seed predators, stem borers, gall makers and sap suckers. These four guilds differed in habits and behaviour, the first three being sessile and endophytic and the last being free-living.
3. This study shows that the abundance of all four guilds was negatively affected by ungulates. However, the effect on attack rate differed among guilds, as mammals do not affect the seed predator attack rate. Ungulates also differentially affected insect survival, ingesting only seed predators and gall makers.
4. In summary, this study suggests that diverse mechanisms may affect different insect guilds in different ways. Therefore, competition between disparate herbivores appears to be complex and can be provoked by multiple mechanisms.