Value Of Lac Research Articles

Monitoring of biofilm in cooling water system by measuring lactic acid consumption rate

Biofilm formation in cooling water systems causes many problems such as increase of the frictional resistance in tubes and decrease in the heat exchange capacity of heat exchanger. Monitoring of biofilm formation in the system is necessary to avoid biofilm related problems and optimize biocide addition. However, detection of biofilm formation in the whole system is difficult. To solve this problem, a novel and simple method for monitoring biofilm was developed in this study. Biofilm consists of living microorganisms, and nonliving organic and inorganic substances. Microorganisms in the biofilm consume substrate in the circulating cooling water. Therefore substrate consumption rate reflects biofilm activity in the system. Experiments were scaled up stepwisely; i.e. beaker-scale, bench-scale, and operating plant experiments. The beaker-scale experiment was conducted to select suitable substrate. Among the eight substrates examined, lactic acid was the most bio-consumable one by the biofilm formed on carbon steel coupon. The lactic acid consumption rate ( R lac) was estimated at 273 mg/(m 2 h). The R lac value was compared before and after the hydrogen peroxide wash of the bench-scale plant. The R lac before the wash was 36.3 mg/(m 2 h). On the other hand, the R lac after the wash was negligible. An experimental study was next conducted in the operating cooling water plant. A rapid decrease of lactic acid concentration in the circulating water of a relatively unclean system was shown. On the other hand, R lac in a clean system was low. This simple method provided us information on biologically active biofilm formation in the system.

Purification and Characterization of Two Laccase Isoenzymes from a Ligninolytic Fungus Trametes gallica

Constant laccase activities were detected in culture supernatant of newly isolated basidiomycete Trametes gallica. Tryptone and glucose have great effects on the production of laccase. Two laccase isoenzymes (Lac I and Lac II) produced by T. gallica were purified to homogeneity (51‐ and 50‐fold, respectively) by gel filtration chromatorgraphy, anion exchange chromatography, and improved native PAGE, with an overall yield of 24.8%. Lac I and Lac II from this fungus are glycoproteins with 3.6% and 4% carbohydrate content, the same molecular masses (by SDS‐PAGE) of 60 kDa, and the pI of 3.1 and 3.0, respectively. Native gel electrophoresis indicates that the two laccases have different migration ratios. Lac I and Lac II have the same optimal pH of 3.0 on 2,6‐dimethoxyphenol (DMP), pH 2.2 on 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS), and of pH 4.0 on guaiacol. The highest rate of ABTS oxidation for both laccases was reached at 70°C. Both laccases are stable from pH 6 to 9, retaining 88–90% activity after 24 hr incubation, and show good stability when incubated at temperatures lower than 40°C. The K m values of Lac I for ABTS, DMP, and guaiacol are 0.118 × 10−2, 0.420, and 0.405 mM, respectively; the K m values of Lac II for ABTS, DMP, and guaiacol are 0.086 × 10−2, 0.41, and 0.40 mM, respectively. Their N‐terminal sequences are determined and show strong similarity with those from other basidiomycetes. Graphite‐furnace atomic absorption analysis revealed that both laccases have four copper atoms per protein molecule, but they have no type I copper signal at around 600 nm and a type III copper signal near 330 nm. Cyanide, azide, and halides completely inhibit the enzyme activity, whereas EDTA has less inhibition.

Penetration of Photosynthetically Active Radiation as a Measurement of Canopy Density of Citrus Trees1

Abstract Citrus trees were defoliated to obtain measurements of radiation penetration at various canopy densities. Tree size measurements were used to calculate the leaf-area index (LAI) and leaf-area to canopy-area ratio (LAC) of trees. Penetration of photosynthetically active radiation (PAR) increased curvilinearly as defoliation increased and LAC decreased. Observed relationships between PAR penetration and LAC were used to estimate LAC values from PAR penetration measurements. Correlations between PAR penetration and LAC were slightly higher than with LAI. LAI and LAC appeared to vary independently from tree size as measured by tree diameter or leaf area.

Purification and properties of allelic lactate dehydrogenase isozymes at the B 2 locus in rainbow trout, Salmo gairdneri

1. 1. The homotetrameric lactate dehydrogenase (LDH) isozymes, B 4 2′ and B 4 2″, from homozygous rainbow trout livers have been purified to homogeneity by affinity chromatography using a Sepharose-linked oxamate ligand. 2. 2. The B 4 2″ isozyme has been found: (a) to have increased K m (pyr) and K i (lac) values, (b) to bind pyruvate strongly in the absence of coenzymes with a binding constant of 4.02 × 10 4 M −1 under conditions where other LDH isozymes showed no binding, and (c) to give a nonlinear noncompetitive lactate product inhibition pattern compared to a normal linear noncompetitive inhibition for the B 4 2′ isozyme. 3. 3. Different kinetic mechanisms have been proposed for the two isozymes and an adaptive functional significance has been discussed.

Iodometric Determination of Acid Value of Lac

Iodometric Determination of Acid Value of Lac

Reports and other Publications

(not included in the monthly Books Supplement) Great Britain and Ireland London Shellac Research Bureau. Bulletin No. 3: Iodine Values of Lac; Reaction between Halogen and Lac. By Dr. B. S. Gidvani and Dr. R. Bhattacharya. Pp. 14. Technical Paper No. 17: Ethers and Ether-Esters of Lac and their Polymerisation. By Dr. B. S. Gidvani. Pp.24. (London: London Shellac Research Bureau.) [31

THE LAC INDUSTRY

Many of us are, perhaps, unaware of the extreme economic importance of Lac Industry in India. It is a most fascinating subject as may be seen from the extensive use made of lac in the manufacture of many of the articles in common use such as sealing wax, gramophone records, varnishes, lacquer- ware, wooden toys, electrical goods, dyes, etc. The fact that, except for a small percentage contributed by Annam and Siam, India practically holds the monopoly for the world supply of this commodity, should be sufficient reason to justify our taking greater interest in the cultivation and production of lac. It is upto us to see that this industry is developed to the utmost on up-to-date lines so as to enable our controlling and dictating prices in the world market, instead of depending as at present upon the whims and fancies of purchasers in the foreign market. The total quantity and value of lac exported from India, as shown in the following table, indicate that this industry is by no means such a small and negligible one as it is supposed to be.

The Lac and Shellac Industry in India1

AT the present time India holds what is virtually a monopoly of lac production, and no satisfactory substitute has yet appeared on the world's markets. This monopoly cannot, however, be regarded as a sinecure; other countries are likely to be found suitable for lac cultivation, and the present high value of lac and its importance to many Western industries render it urgent that the production of this substance should be encouraged along improved scientific and economic lines. The propagation of lac is still very carelessly carried out, and its methods of collection need much improvement. The crop varies from year to year, prices fluctuate seasonally, and there is much injurious market speculation. The bulk of the world's lac comes from Chota Nagpur, Orissa, the north-eastern half of the Central Provinces, some western districts of Bengal, and from part of the Mirzapur district of the United Provinces. Out of the ninety or more trees which have been recorded as hosts for the lac insect (Tachardia lacca), the most important include Schleicheria trijuga, Butea frondosa, Zizyphus jujuba and xylopyrus, together with species of Acacia, Ficus, etc. These plants contain much gummy or resinous matter or are rich in latex.