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Soil is the outer loose layer of earth consisting of layers of mineral material (regolith) whose properties differ from one another and these differences are largely due to the variation in biological activities. Soil micro-environment principally comprizes of inorganic particulates (sand, silt and clay) plus certain oxides and hydroxides, plant roots, organic matter, microbial biomass and aqueous and gaseous phases. The uneven distribution of these components provides a great variety of conditions from field to micropores. The interaction of physical and chemical factors contributes to the creation of varied soil habitat and hence determines the composition and activity of soil biota at a particular site and time. Over geological times, microorganisms have had great opportunity to become distributed worldwide. Such growth and development of microorganisms as well as species diversity is of considerable significance. The existing geographic distribution is reflective of long term adaptation of microorganisms to the various environmental conditions. The preferred environment of an organism is usually referred as ‘habitat’.

The plant roots, soil animals and microorganisms make up soil biological communities, accelerate biochemical activities through intra- and extra-cellular enzymes and interact in such a manner that biogeochemical cycling on this earth continues uninterrupted. Without intermeshing vital processes of soil microflora, microfauna and associated mesofauna, the soil would have become a repository of plant residues and animal remains with no facility for recycling the vital nutrients for plant growth, thus halting the whole process of geo-chemical recycling in nature. Though living component rarely makes up more than 4% of the total soil organic carbon, it plays vital role in geochemical recycling, soil development and ecosystem stability.

Definition : Soil microbiology is the study of microorganisms living in soil which complete whole or some part of their life cycle in soil. They include both beneficial as well as deleterious microorganisms but as a specialized branch main thrust is laid on their metabolic activities and the role they play in energy flow, cycling of nutrients associated with the primary productivity and soil ecosystem development. Besides, it focuses on environmental impact, whether favourable or unfavourable, on soil microorganisms and the various soil biochemical processes mediated by various microbes. A clear understanding of the interactions between soil microbial communities and elemental soil components is imperative to comprehend total ecosystem function. Atlas and Bartha have defined the soil microbiology as ‘the study of organisms that live in soil; their metabolic activity; their roles in energy flow; their roles in nutrient cycling’. As per Tate soil microbiology involves ‘the study of soil ecosystem which is the product of intricate interactions between physical and chemical matrix of highly variable composition and living communities of all form’.

PGPR have shown potentiality against pests and diseases oc curring on crop plants. Wilt and collar rot diseases are caused by soilborne pathogens viz., Fusarium oxysporum fsp. lycopersici (FOL) and Sclerotium rolfsii respectively in vegetables. An attempt was made to manage the diseases with PGPR microbes and 142 PGPR strains were isolated from different vegetable crops. Among them two isolates viz., Bacillus amyloliquefaciens (BA1) and B. subtilis (BS2) were found highly effective in controlling the diseases.  Apart from the disease control, the isolates BA1 and BS2 also registered enhanced crop growth and yield in cowpea under field conditions. Species level identification of BA1 and BS2 was done through PCR amplification and sequencing of 16s rRNA. Both BA1 and BS2 clustered with Bacillus amyloliquefaciens and B. subtilis respectively.

Mastitis is a global problem as it adversely affects animal health, quality of milk and economics of milk production. Bovine Mastitis is reported to be the most costly disease of dairy cattle, causing huge economic losses in terms of reduced milk yield, milk discard after treatment, cost of veterinary services and premature culling. While reviewing status of mastitis in India, subclinical mastitis is more important (10–50%) than the clinical mastitis (1-10%). Estimated annual economic losses incurred due to mastitis estimates to Rs.7165.57 crores to dairy farmers (Bansal and Gupta, 2009).

Investigations were undertaken to isolate the fluorescent pseudomonads from the soil and root samples collected from Western Ghats regions of Chikkamagalur district of Karnataka. A total of nine isolates were obtained from 10 sampling sites. All the nine isolates were subjected for morphological, physiological and biochemical characteristics and were tentatively identified as Pseudomonas fluorescens. Isolates were examined for different agriculturally important functions like production of plant growth promoting substances (PGPS), solubilization of TCP and biocontrol activity. Results of the study indicated that, five out of nine isolates found positive for IAA production and the amount of IAA production ranged from 1.92 to 6.75 mg per ml.

Introduction

The rumen ecosystem is essentially a fermentation system that houses a vast array of different microbes. Ruminants typically browse low energy forages, such as grasses or other plant material, rich in fibre but not easily accessible to the ruminant without rumen fermentation. These forages are literally food for the microbes present in the rumen first and then, in turn, the products of these microbes are the feed for the ruminant. Microbes break down forage in the anaerobic rumen environment and the products of microbial fermentation provide the ruminant with metabolisable compounds, such as short chain fatty acids, while the microbes themselves account for around 90% of the amino acids entering the lower intestine. There are many significant challenges to investigate rumen ecology.

One of the integral components of human and animal liveli hood is food and water without which life cannot sustain on  earth. However, due to high nutritive value of foods and ubiquitous nature of microbes, it is always at risk of microbial spoilage and contamination. World Health Organization (WHO) defined “food-borne illnesses” as diseases, usually either infectious or toxic in nature, caused by agents that enter the body through the ingestion of food. Every consumer is at risk of food-borne illness but conversely every incidence of foodborne illness is potentially preventable. Several bacterial pathogens in particular are responsible for foodborne infections and intoxications.

Globally, 2 billion children under the age of five suffer from diarrhoea, of which, more than 50% of the cases being in South Asia and sub-Saharan Africa, where the disease is more likely to be fatal (UNICEF-WHO, 2009). It has been also estimated that the great majority of acute diarrhoeal illnesses in children over the age of two years is attributable to bacterial pathogens (Carpenter, 1980). Amongst the various enteric bacterial pathogens, diarrheagenic strains of Escherichia coli are considerably responsible for causing bacterial diarrhea (Nataro and Kaper, 1998).

Microbial diversity is the key to human survival and economic well being. It provides a huge reservoir of resources which can be utilized for our benefit. Yeasts have been isolated from many sources for industrial purposes. The impact of yeasts on food and beverage production extends many fold beyond the popular notions of bread, beer and wine fermentations by Saccharomyces cerevisiae.

Diverse dynamic mixed populations of prokaryotic and lower eukaryotic microorganisms govern the fermentation and maturation processes and, finally, impact the quality of wine. Both of these parameters apparently contribute to regional differences in the quality of produced wines and characterization of regional wines should involve the study of microbial populations and their members active in the given region.

Ralstonia solanacearum is a phytopathogenic bacterium belong ing to the b subdivision of the Proteobacteria (Yabuuchi et al., 1995) having a wide geographical distribution ranging from tropical, subtropical and warm temperate regions (Liu et al., 2009). It has broad host range and infects around 54 plant families and 450 plant species (Hayward, 1991; Wicker et al., 2007). 

Early attempts to study the diversity present in the R. solanacearum species complex resulted in separate race and biovar systems. R. solanacearum has been phenotypically classified into 5 races based on the host range at the plant species level and into five biovars based on the metabolic profiles related to the ability to reduce three disaccharides and three hexose alcohols (Wicker et al., 2007).

Microorganisms are diverse group of organisms differing in many ways and range from saprophytic to virulent one. Virulent are pathogenic and harmful to human and animals and can cause latent to per acute disease. Nowadays although treatment is available for most of the diseases, it is better to prevent the disease rather than going for treatment. Development of immunity is the aim of immunization and hence through knowledge of the host parasite interaction, epitope of the microorganisms responsible for the inducing protective immune responses is of pivotal importance.

Many microbes have ability to attach to various surfaces forming three dimensional extracellular matrix within which embedded the microbes grow and multiply forming thin layer structure called biofilm. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings (Hall-Stoodley et al., 2004). Biofilm mainly consist of three components - bacteria, matrix and surface. Extracellular matrix generally composed of extracellular polymeric compounds such as extracellular polysaccharides, proteins, phospholipids, DNA, teichoic and nucleic acids, and other polymeric substances hydrated to 85 to 95% water and polysaccharides (Hall-Stoodley et al., 2004).

Production of Indole-3 Acetic acid (IAA) and mineral phosphate solubilization (MPS) are two predominant and direct mechanisms used by plant growth promoting rhizobacterial strains (PGPR). These traits are widespread among bacteria. Moreover, the role of IAA in plant-microbe interactions is diverse varying from pathogenesis to phytostimulation, to its role as a signaling molecule in microorganisms. With the advent of high performance analytics, molecular tools and recombinant methods, it has become feasible to investigate biochemical pathways of bacterial IAA synthesis at the genetic, biochemical and chemical levels. In the current study, we isolated several PGPRs from Western Ghats region, India.  Of all the efficient isolates, Serratia marcescens SM15 emerged as the most efficient PGPR isolate based on in vitro plant growth assays and ability to express PGPR traits.

Polyhydroxyalkanoates (PHAs) are diverse biopolyesters synthesized by many bacteria as carbon and energy reserved materials under unbalanced growth conditions. Sand-dunes have low nutrient contents especially nitrogen (N) and phosphorus (P) thus could harbor potential PHA accumulating bacteria. There is no report of isolation of PHA producing bacteria from the sand-dunes environment.  Sand samples of rhizosphere and non-rhizosphere regions of the coastal sand-dunes were processed on Nutrient Agar and TYG-Agar media for isolation of heterotrophic bacteria.

The diversity of the haloarchaea found within a crystallizer pond of a solar saltern located in Siridao and Ribandar, Goa, India was examined. Both cultured-based and culture independent methodology were employed which included  surface spreading of samples on different media containing 25% crude salt/NaCl, DNA extraction from sediment and water samples, amplification of 16S rRNA gene and DGGE.

Introduction

Mosquito-borne diseases such as malaria, filariasis, Japaneseencephalitis, chikungunya and dengue hemorrhagic fever cause extensive morbidity and take heavy toll of life in the developing nations particularly in the tropics. Every year about 300-500 million people are estimated to be affected by malaria alone (WHO report, 2000). In India around two million cases of malaria are being reported annually although real burden is many fold higher (Kumar et al. 2007). Similarly, lymphatic filariasis caused by Wuchereria bancrofti affects about 120 million people worldwide. India contributes about 40%  to  the total global burden of filariasis and accounts for about 50% of the people at risk of infection (ICMR bulletin, 2002). Anopheles stephensi is recognized as a major vector for urban malaria in India (Kumar 1997).

Introduction

Foraminifera or forams for short are the most abundant, diverse and widely distributed Protists in marine realm. They are found in all marine environments, from the inter-tidal to the deepest ocean trenches, and from the tropics to the poles (Todo et al., 2005). In some places, foraminifera are so abundant that the sediment on the bottom is mostly made up of their shells. For example, tourists from all over the world get attracted to the pink sands of Bermuda. These sands get their colour from the shells of Homotrema rubrum which has pink to red-colored shells. Living representatives of foraminifera provide ecological data and their mineralized tests are a geochemical record of palaeoclimatic conditions.

Introduction
 
Biodiversity a term to describe variability between organisms or populations of organisms, has different facets depending on the level of diversity considered (Species, population, ecosystem) or the organisms concerned (Barbault, 1992). Biodiversity can be exploited in many ways at scientific levels, the best known and the most ancient no doubt being in taxonomy and systematics, and more recently for studies of population biology, evolution and conservation of ecosystems, or for selection of materials for biotechnology.

The quest for drugs from the sea has yielded a remarkable di versity of natural products mostly from invertebrates such as sponges, tunicates, bryozoans etc. These molecules are either in late stages of clinical trials or have already entered the market. There has been an increased emphasis on marine microorganisms as sources of bioactive compounds over the past decade. Marine bacteria alone constitute 10% of the total living biomass carbon of the Earth’s biosphere and they have unique metabolic and physiological capabilities to ensure their survival in diverse habitats. In the marine environment, some microorganisms associate with living and non-living surfaces and the competition amongst these microbes for space and nutrients leads to the production of bioactive secondary metabolites.