Marine yeasts — a review

Yeasts are ubiquitous in their distribution and populations mainly depend on the type and concentration of organic materials. The distribution of species, as well as their numbers and metabolic characteristics were found to be governed by existing environmental conditions. Marine yeasts were first discovered from the Atlantic Ocean and following this discovery, yeasts were isolated from different sources, viz. seawater, marine deposits, seaweeds, fish, marine mammals and sea birds. Nearshore environments are usually inhabited by tens to thousands of cells per litre of water, whereas low organic surface to deep-sea oceanic regions contain 10 or fewer cells/litre. Aerobic forms are found more in clean waters and fermentative forms in polluted waters. Yeasts are more abundant in silty muds than in sandy sediments. The isolation frequency of yeasts fell as the depth of the sampling site is increased. Major genera isolated in this study were Candida, Cryptococcus, Debaryomyces and Rhodotorula. For biomass estimation ergosterol method was used. Classification and identification of yeasts were performed using different criteria, i.e. morphology, sexual reproduction and physiological/biochemical characteristics. Fatty acid profiling or molecular sequencing of the IGS and ITS regions and 28S gene rDNA ensured accurate identification.

Antiviral property of marine actinomycetes against White Spot Syndrome Virus in penaeid shrimps

Aquaculture farms, particularly in Southeast Asia are facing severe crisis due to increasing incidences of White Spot Syndrome Virus (WSSV). Actinomycetes have provided many important bioactive compounds of high prophylactic and therapeutic value and are continually being screened for new compounds. In this communication, the results of a study made to determine the effectiveness of marine actinomycetes against the white spot disease in penaeid shrimps are presented. Twenty-five isolates of actinomycetes were tested for their ability to reduce infection due to WSSV among cultured shrimps. When these actinomycetes were made available as feed additives to the post-larvae of the black tiger shrimp Penaeus monodon for two weeks and challenged with WSSV, the post challenge survival showed variations from 11 to 83%. However, six isolates have shown to be the most potential candidates for further study.

Studies on the Benthic Fauna of the Mangrove Swamps of Cochin Area

Division of Marine Biology, Micrbiology and Biochemistry,Cochin University of Science and Technology

Electrophoretic, Biochemical and Morphometric studies on Three Bivalves of Cochin and Nearby Waters

Division of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology

Investigations on the Effects of Petroleum Hydrocarbons on the Marine Bivalves Perna viridis (Linnaeus) and Sunetta scripta (Linne')

The thesis deals with different aspects connected with the distribution and toxicity of PHC in crude oils in the aquatic environment and marine molluscs. Information has been gathered and presented on the present status of research in the field based on a thorough review of recent literature. It is seen from the literature that the resident time of PHC becomes lesser and lesser when crude oil is discharged in large quantities into the coastal waters where excess oxygenation light penetration, temperature availability and strong tidal currents persist. This results in the reduction of the onslaught of oil pollution. This probably shows that taxic insult of crude oil in tropical shores will be relatively lesser than that occurring in temperate and boreal waters. However, there is no record of major episodal oil pollution comparable in quantum and extent to that of Torrey Canyon or Amoco Cadiz which prevents a more reliable analysis on the issue. Considerable controversy exists on the method of estimation of PHC in seawater. However, Ultra-violet fluorescence spectroscopy has been widely recommended as an analytical tool for the determination of total hydrocarbons. Similarly representation of values as chrysene equivalents has been recognised as the most reliable method of Quantum representation.

Culture and Nutritional Enrichment of the Rotifer Brachionus Rotundiformis ( Tschugunoff ) for the Rearing of Marine Fin Fish and Shrimp Larvae

The present study is an attempt to standardize the environmental condition like pH, salinity and photoperiod, and also the feed for the maximum production of rotifers. Considering the deficiency of essential fatty acids in rotifers, enrichment experiments were carried out and fatty acids profile were analysed. Attempts were made to improve the production of clown fish (Amphiprion sebae) juveniles using enriched rotifers. Attempts were also made to rear various larval stages of Penaeus monodon with enriched rotifers as a substitute for Artemia nauplii.

Meiobenthos of the Shelf Waters of West Coast of India With Special Reference to Free-Living Marine Nematodes

Department of Marine Biology, Microbiology and Biotechnology, Cochin University of Science and Technology

Sulphur Chemistry in Mangrove Systems of Tropical Cochin Estuary

Sulphur is a non conservative major element and is the most active species in the redox processes in nature, especially in aquatic environment . The varying oxidative states from-2 to +6 make it possible to enter into many of the biogeochemical processes. Thus the history, present and future of the chemical composition and behaviour of the natural aquatic systems and sediments have footprints of the sulphur chemistry.Mangroves are considered to be the most productive, fishery supportive ecosystem operating in the intertidal regions. The interlinking of the mangroves with the sulphur chemistry is attempted here.

Acidity and catalytic activity of rare earth modified Al/Zr pillared clays

The pillared montmorillonite has been prepared by exchanging Na+ in the interlayer of montmorillonite with Al hydroxy cation followed by calcination. Pillared clays are also prepared after exchanging Na' ions with Ce, La, Sm-ions and then pillarcd with aluminium oxides, The surface characterisation of the prepared catalysts has been done using XRD and surface area measurements. To probe the acidic property of the system, temperature programmed desorption (TPD) of NH, has been done. Toluene alkylation by benzyl chloride has been carried out for the evaluation of catalytic activity. The most active system is found to be mixed Al/Zr pillarcd montrnorillonite.

Studies on Dredging Impact Assessment(DIA) at Cochin, A Tropical Estuarine Harbour

Department of Physical Oceanography, School of Marine Sciences,Cochin University of Science and Technology

Biochemical Effects of Anionic, Cationic and Non Ionic Surfactants on a Tropical Teleost Oreochromis Mossambicus(Peters) and a Marine Cyanobacterium Synechocystis Salina Wislouch

The present work is a base line attempt to investigate and assess the toxicities of three surfactants viz. anionic sodium dodecyl sulfate (SDS), non ionic Triton X-1OO (TX-IOO) and cationic cetyl trimethyl ammonium bromide (CTAB). These compounds represent simple members of the often neglected group of aquatic pollutants i.e. the anionic alkyl sulfates, non ionics and the cationics. These compounds are widely used In plastic industry, pesticide/herbicide formulations, detergents, oil spill dispersants, molluscicides etc. The test organisms selected for the present study are the cyanobacterium Synechocystis salina Wislouch representing a primary producer in the marine environment and a fresh water adapted euryhaline teleost Oreochromis mossambicus (peters) at the consumer level of the ecological pyramid. The fish species, though not indigenous to our country, is now found ubiquitously in fresh water systems and estuaries. Also it is highly resistant to pollutants and has been suggested as an indicator of pollution in tropical region .

Liquid phase benzylation of o-xylene over pillared clays

Iron, aluminium and mixed iron aluminium pillared clays have been prepared by partial hydrolysis method and doped with IO% Mo, V and Cr. The samples have been characterised by XRD, FTIR and surface area and pore Volume measurements. The surface acid site distribution has been determined by temperature programmed desorption of ammonia. Vanadia incorporated systems show maximum acidity. Benzylation of o-xylene has been done as probe reaction to test catalytic activity. Benzyl chloride is a superior benzylating agent compared to benzyl alcohol in activity and selectivity. Cent percent selectivity towards monobenzylated product is obtained in all the cases. Fe pillared systems exhibit maximum activity. The catalytic activities of the systems can be correlated with the amount of strong add sites. The effects of various reaction variables on the reaction have been studied. Presence of moisture has a diminishing effect on the reaction rate.

Selective Methyl Tert-Butyl Ether Synthesis over Metal Exchanged Pillared Clays

Iron and mixed iron aluminium pillared montmorillonites prepared by partial hydrolysis method was subjected to room temperature exchange with transition metals of the first series. The materials exhibit good structural as well as thermal stability. Exchanged metals were found to be present inside the porous network, in the environs of the pillars. Mixed pillaring resulted in the intercalation of Al 13 like polymers in which Al is partially substituted by Fe. The acidic structure was followed by temperature programmed desorption of ammonia and cumene cracking test reaction. Weak and medium sites overshadow the strong sites in all systems. However, exchange with metals increases the number of strong sites. The prepared materials are efficient catalysts for gas phase MTBE synthesis. The catalytic activity can be well correlated with the total amount of weak and medium acid sites.

Marine yeasts as source of single cell protein and immunostimulant for application in penaeid prawn culture systems

The study revealed the potential of marine yeasts as a source of single cell protein and immunostimulant for prawns. Prawns fed with the selected marine yeasts were showing more growth compared to the control feed and commercial feed. Yeasts being rich with proteins, vitamins and carbohydrates serve as a growth promoter for prawns as being evidenced in this study. The better performance of marine yeasts, D. hansenii S8 and S100 and C. tropicalis S186 compared to S. cerevisiae S36 as a feed supplement is worth investigating. Besides being a rich nutritional source, yeasts act as immunostimulants by virtue of its high carbohydrate (Beta, 1-3 glucan) and RNA content. Beta, 1-3 glucan, a cell wall component of yeasts /fungi is the most commonly used immunostimulant in aquaculture. The present study shows that even the whole cell yeast could serve as a good immunostimulant when supplied through diet. Extraction of Beta-1,3 glucan results in the removal of nutrients like proteins, vitamins etc. from the cell biomass.Utilization of the yeast biomass as such in the diet would help perform a dual role as nutritional component and immunostimulant for aquaculture applications.

Process Optimization for Mass Production of Marine Yeast Candida sp. S 27 and its Nutritional Characterization

The main source of protein for human and animal consumption is from the agricultural sector, where the production is vulnerable to diseases, fluctuations in climatic conditions and deteriorating hydrological conditions due to water pollution. Therefore Single Cell Protein (SCP) production has evolved as an excellent alternative. Among all sources of microbial protein, yeast has attained global acceptability and has been preferred for SCP production. The screening and evaluation of nutritional and other culture variables of microorganisms are very important in the development of a bioprocess for SCP production. The application of statistical experimental design in bioprocess development can result in improved product yields, reduced process variability, closer confirmation of the output response to target requirements and reduced development time and overall cost.The present work was undertaken to develop a bioprocess technology for the mass production of a marine yeast, Candida sp.S27. Yeasts isolated from the offshore waters of the South west coast of India and maintained in the Microbiology Laboratory were subjected to various tests for the selection of a potent strain for biomass production. The selected marine yeast was identified based on ITS sequencing. Biochemical/nutritional characterization of Candida sp.S27 was carried out. Using Response Surface Methodology (RSM) the process parameters (pH, temperature and salinity) were optimized. For mass production of yeast biomass, a chemically defined medium (Barnett and Ingram, 1955) and a crude medium (Molasses-Yeast extract) were optimized using RSM. Scale up of biomass production was done in a Bench top Fermenter using these two optimized media. Comparative efficacy of the defined and crude media were estimated besides nutritional evaluation of the biomass developed using these two optimized media.