Optimum culture medium composition for lipopeptide production by <Emphasis Type="Italic">Bacillus subtilis</Emphasis> using response surface model-based ant colony optimization

Central composite rotatable design (CCRD) of experiments was used to obtain data for Lipopeptide and Biomass concentrations from fermentation medium containing the following five components: glucose, monosodium glutamate, yeast extract, MgSO₄?7H₂O, and K₂HPO₄. Data was used to develop a second order regression response surface model (RSM) which was coupled with ant colony optimization (ACO) to optimize the media compositions so as to enhance the productivity of lipopeptide. The optimized media by ACO was found to yield 1.501 g/L of lipopeptide concentration which was much higher compared to 1.387 g/L predicted by Nelder–Mead optimization (NMO). The optimum from ACO was validated experimentally. RSM-based ACO is thus shown to be an effective tool for medium optimization of biosurfactant production.     

In vivo demonstration of enhanced probiotic effect of co-immobilized Lactobacillus acidophilus and Bifidobacterium bifidum

The present study was undertaken to evaluate the effectiveness of co-immobilization as an efficient method for delivering high numbers of viable probiotic cultures to the host for an enhanced probiotic effect, using in vivo mice models. The co-immobilized culture of Lactobacillus acidophilus and Bifidobacterium bifidum was fed to eight groups of conventional mice. A greater persistence of probiotic cultures was noticed in the intestinal contents of the groups fed on co-immobilized cells. Further, the supplementation of diet with co-immobilized culture also resulted in maximum lowering of faecal coliforms and the enzymatic activity as compared to the prestudy level.     

PRELIMINARY STUDIES ON PHYSICAL AND NUTRITIONAL QUALITIES OF SOME INDIGENOUS AND IMPORTANT RICE CULTIVARS OF NORTH‐EASTERN HILL REGION OF INDIA

ABSTRACT

The northeastern hills of India are endowed with rich source of rice germplasm, which may be safely estimated about 9,000 accessions, excluding the redundancies. Even though much of the germplasm have been collected, studies on nutritional aspects of these local cultivars are still lacking. Fifteen important indigenous rice genotypes collected from different rice growing ecosystem of this region were studied for physical and nutritional qualities. Kernel color of the genotypes varied from white to dark purple. All the genotypes except Manipuri were of bold‐grain type. Most of the genotypes studied have fat contents more than 2.0%. The protein content was found higher in Chahou angouba and Naga special. Five cultivars were identified as high‐protein cultivars of rice, with 10–12.07% protein content. Amylose content varied from 2.27 to 24.5%. Most of long‐grained genotypes recorded lesser amylose than short grained. Chahou varieties were found aromatic and glutinous, which demand higher market prices in local market.

PRACTICAL APPLICATION

The north‐eastern hills of India are endowed with rich source of rice germplasm, and much of the germplasm have been collected, but studies on basic and advanced nutritional aspects of these local cultivars are still lacking. This part of India has valuable rice genotypes of strong aroma, glutinous characters and slender grains with high amount of protein, fat and fiber. Having not known to the rest of the world and even to indigenous end users, some of such cultivars have already been lost, and some more are at the verge of extinction. Quality evaluation done in the present study provided useful information on their commercial exploitation and utilization in breeding programs of nutritional enhancement of rice to fight malnutrition among rice‐consuming population, which is largest in the world.     

Kinetics of Ammonia Leaching of Multimetal Sulphides

This paper briefly describes the studies carried out on oxidative ammonia leaching of Cu-Zn-Pb multimetal sulphides. Kinetics of zinc and copper dissolution were studied with ? 200 + 300 mesh BSS fraction and 1% solids in the slurry. It is observed that the dissolution of sphalerite proceeds by a phase boundary reaction model and that of copper via diffusion through product layer in the temperature range of 70-100°C. The rate equations for zinc and copper dissolution are given by:

1 ? (1 ? α)^1/3 = k _Zn[NH₃][pO₂]^1/2

1 ? 2/3α ? (1 2/3α )^2/3 = k^Cu[NH₃]²[pO₂]^1/2

where the symbols have the usual meanings.

Activation energies for zinc and copper dissolution reactions are estimated to be 66.5 and 55.4 kJ/mole, respectively. Activation energy values thus obtained are also comparable to those obtained using a differential approach.

The leaching results obtained with 10% solids using a wide range of particle size (? 140 + 500 mesh) indicate that copper dissolution is chemically controlled in ammonia as well as ammonia-ammonium sulphate medium in the temperature range of 115-135°C. However, at lower temperature (?55°C). the leaching reaction follows a diffusion model. Zinc dissolution data show deviations from the shrinking core model due to high extractions in the initial stages.     

Study of liquid fuel transport in a small carburetted engine in the context of cold-start HC emission control

In the present study, a detailed visualization of the transport of fuel film has been performed in a small carburetted engine with a transparent manifold at the exit of the carburettor. The presence of fuel film is observed significantly on the lower half of the manifold at idling, while at load conditions, the film is found to be distributed all throughout the manifold walls. Quantitative measurement of the fuel film in a specially-designed manifold of square cross section has also been performed using the planar laser-induced fluorescence (PLIF) technique. The measured fuel film thickness is observed to be of the order of 1 mm at idling, and in the range of 0.1 to 0.4 mm over the range of load and speed studied. These engine studies are complemented by experiments conducted in a carburettor rig to study the state of the fuel exiting the carburettor. Laser-based Particle/Droplet Image Analysis (PDIA) technique is used to identify fuel droplets and ligaments and estimate droplet diameters. At a throttle position corresponding to idling, the fuel exiting the carburettor is found to consist of very fine droplets of size less than 15 μm and large fuel ligaments associated with length scales of the order of 500 μm and higher. For a constant pressure difference across the carburettor, the fuel consists of droplets with an SMD of the order of 30 μm. Also, the effect of liquid fuel film on the cold start HC emissions is studied. Based on the understanding obtained from these studies, strategies such as manifold heating and varying carburettor main jet nozzle diameter are implemented. These are observed to reduce emissions under both idling and varying load conditions.     

D.C. conductivity and spectroscopic studies of polyaniline doped with binary dopant ZrOCl<Subscript>2</Subscript>/AgI

Aqueous binary dopant (ZrOCl₂/AgI) is used in different ratios such as 1:1, 1:2 and 2:1 (w/w) for chemical doping to enhance the conductivity of synthesized polyaniline (PANI). The doping of polyaniline is carried out using tetrahydrofuran as a solvent. Doped samples are characterized using various techniques such as I–V characteristics, UV-visible spectroscopy, X-ray diffractometry (XRD), FTIR and photoluminescence (PL) studies. A significant enhancement in d.c. conductivity has been observed with the introduction of binary dopant. UV-visible study shows that optical parameters change considerably after doping. Interestingly, both direct and indirect bandgaps are observed in the doped samples. XRD patterns show the semi-crystalline nature of doped polyaniline. FTIR study shows structural modifications in functional groups with doping in PANI. Photoluminescence spectra exhibit emission properties of the samples.     

The effects of biofilms formed on whey reverse osmosis membranes on the microbial quality of the concentrated product

The study investigated the development of bacterial biofilms on spiral wound reverse osmosis (RO) whey concentration membranes and their influence on the microbial quality and safety of concentrated whey (retentate). Used RO membranes, obtained from a commercial whey processing plant, were evaluated at intervals of 2 months for a total duration of 14 months using standard techniques. Results confirmed the presence of multi‐species bacterial biofilms on whey RO membranes. Considerable variations were noticed in the distribution pattern of biofilms constitutive microflora as the membranes aged. A greater increase in retentate counts as compared to feed suggested the possibilities of cross‐contamination from the membrane biofilms.