eChapters

Biopesticides are pesticides that are produced naturally by plants, animals, microbes, and other minerals. These represent less of a harm to humans and the environment than chemical insecticides. Nanotechnology is a rapidly developing scientific topic that has numerous uses in numerous industries, including agriculture. The transport of plant hormones, seed germination, water management, transfer of target genes, nano barcoding, nano sensors, and controlled release of agrichemicals are now being investigated as applications for nanotechnology in agriculture (Worrall et al. 2018).

Three kinds of biocontrol products are being used in India which include 1) Microbial biopesticides, 2) Plant-derived botanical pesticides, and 3) Pheromones or other natural insect growth regulators. Microbial biopesticides consist majorly of fungi, bacteria, viruses or entomopathogenic nematodes as bioactive principles.

The biocontrol use had almost completely disappeared due to the growth and success of the synthetic pesticide industry in the mid-1940s. The publication of Rachael Carson's 'Silent Spring' (Carson 1962) which condemned the use of agricultural pesticides and emphasized their harmful environmental effects on wildlife. Due to public outrage over this controversial book, there was a need for pesticide alternatives, which presents an opportunity for wider use of biological control (Barratt et al. 2010; Gay 2012).

Insecticides are one of the key control measures to combat the insect pests for sustainable agricultural production in the world. Synthetic insecticides have been only strategy to control the resurgent and resistant insect population in of high value crops not only in India but also in the world. The advent of synthetic insecticides in the mid-20th century made the control of insect and other arthropod pests easy and much more effective, and such chemicals remain essential in modern agriculture despite their environmental issues.

The world population is expected to reach 9 billion by 2050. This population growth of 2 to 3 billion people over the next 30 years, combined with the changing diets, would result in a predicted increase in food demand of around 70% by 2050 (UNDESA 2009).

Introduction

Due to inherent composition (high moisture and nutrients) of meat, it is highly perishable in nature. Hence, preservation of meat is essential to maintain its fresh quality. This is accomplished by various preservative techniques based on the principles of temperature control, moisture control and direct microbial inhibition.

Temperature Control

1. Chilling/Refrigeration

In this method, meat is stored at refrigeration temperature of 2 to 5°C. Chilling of animal carcasses is also carried out during ageing process, cutting transit, retail display and even in consumer household before ultimate use. Relative humidity during chilling is kept about 90%. The fresh meat has shelf life of 5-7 days at refrigerated temperature

Introduction

Resazurin has high tinctorial value (related to colour), imparting characteristic blue colour. Resazurin test gives us indirect information concerning bacterial content and /or activity. Resazurin is also sensitive to the reducing action of leucocytes. The results of this test are comparatively less affected by antibiotic residues in milk than methylene blue reduction test.

Principle

Reduction of dye is indicated by a gradual colour change through various shades of purple and mauve to full pink, at which point the resazurin completely changes to resorufin.

Introduction

Dye reduction tests show the comparative activity of the bacteria in milk, therefore are considered as rough indicator of the number of bacteria per millilitre of milk. These tests find wide application in dairy industry especially in grading of milk for manufacturing purposes. The small amount of equipment, materials and simplicity of method permit simultaneous testing of several samples. Since it combines speed and adaptability, this test may be used in milk plants, receiving stations, condensing plants, cheese factories and similar establishments to rapidly grade incoming milk.

Principle

It is based on the observation that the colour imparted to milk by a small amount of methylene blue disappears in a time, the length of which is dependant largely upon the number of microorganisms

Introduction

Standard Plate Count (SPC) is used for determination of population of viable microbes. Enumeration procedures are based on the assumption that microbial cells present in a sample mixed with an agar medium form visible separated colonies. The bacterial colonies developed on the plates are counted. Each colony is presumed to have developed from one bacterium or clump of bacterial cells. Therefore, the results are expressed in colony counts per /ml of sample or colony forming units per /ml (cfu /ml). Total number of colonies counted on the plate multiplied by the dilution factor represents the number of viable organisms in a sample. SPC is a useful method for evaluating the microbiological quality at various stages of processing. It is also helpful in detecting the source of contamination in the product.

Introduction

Bacteriological examination of milk indicates the hygienic condition of the milk i.e., quality of milk in relation to the health of consumer. Two main objectives of carrying out bacteriological examination are to evaluate the degree of cleanliness in the vicinity of production and handling of milk; and secondly to check the presence of infectious microorganism. Generally, number of bacteria present per milliliter is taken as an index in the routine examination of milk as other tests for identification and differentiation of pathogenic and non-pathogenic microorganisms are time consuming and expensive.

Direct Microscopic Count (DMC) consists of examining stained films of measured volume of milk or milk product, dried on a glass slide under a compound microscope. This method enables rapid estimation of total population of bacteria of a milk sample with relatively more accuracy as compared to other methods.

Introduction

Both beneficiary and deleterious microorganisms are present in food. Beneficiary microbes are used for the preparation of a number of dairy and meat products and are called Probiotics, whereas deleterious microbes can cause food poisoning. The quantitative analysis of food products is necessary to find out the presence of types of microorganisms.

Requirements

1. Food sample
2. Mechanical blender
3. Sterilised distilled water
4. Steilised distilled water blanks (9 ml)
5. Petri plates
6. Sterile Pipettes (1 ml)
7. Eiosin Methylene Blue agar medium
8. Incubator
9. Colony counter
10. Marker

Procedure

1. Weigh 1 g of well blended

Introduction

In recent years, the boom in industrialization has revolutionised the countries but has also added much of sufferings. There is tremendous increase in the water and air pollution. Large amounts of effluents from industries containing organic substances of different nature are discharged and enter the aquatic systems resulting in water pollution. Biological Oxygen Demand (BOD) is the amount of dissolved oxygen required by the aerobic microflora to oxidise the organic matter of dirty water. Increased organic matter results in more oxygen requirements by microorganisms to oxidise it and it results in enhancement of BOD of water. As the BOD of water rises, due to decrease in dissolved oxygen (DO), there is increase in death of fish due to suffocation. Determination of biological oxygen demand (BOD) only is insufficient to give a clear picture of organic content of water bodies and the presence of toxic chemicals in the sample so the chemical oxygen

Introduction

Sugars are commonly found in the form of biopolymers. Cellulose, a biopolymer of glucose is the predominant constituent of plant tissues, and may be shortly described as the structural bases of vegetable world. In this case, the glucose moieties are strung together by P-glycosidase linkages, which form the linear chain, making it resistant to chemical attack. Hemicellulose consists of short, highly branched, chains of sugars. It contains five carbon sugars (usually D-Xylose and L-Arabinose) and six carbon sugars (D-Galactose, D-Glucose and D-Mannose) and uronic acid. Its branched nature renders hemicellulose amorphous and relatively easy to hydrolyse to its constituent sugars. Lignin is a biopolymer rich in phenolic components, which provide structural integrity to plants. Acid and neutral detergent fraction methods (ADF and NDF) involve the gravimetric determination of residue previously treated with acid and neutral detergent solutions. These methods determine the insoluble fraction and their individual components. NDF represents the total plant fibre or cell wall including hemicellulose

Introduction

Organic matter in sediment consists of carbon and nutrients in the form of carbohydrates, proteins, fats and nucleic acids. Bacteria quickly eat the less resistant molecules, such as nucleic acids and many of the proteins. Sediment organic matter is derived from plant/animal detritus, bacteria or plankton formed in situ. Total organic carbon refers to the amount of organic matter preserved within sediment.

Materials

1. Sample
2. Crucibles
3. Furnace

Procedure

Take 1.0 g of sample in a crucible whose empty weight is already recorded. Place this crucible in a furnace. Switch on the furnace and set the temperature at 550°C. Keep the samples for 3 hours

Introduction

The balance between soil organic matter (SOM) levels and nutrient cycling are the key to sustained productivity of agricultural system. Both are closely related through microbially driven mobilisation/immobilisation processes. Three major models have been recognised for C pool viz. Labile C, non-labile C and recalcitrant. The models have been characterised on the bases of their half-life period. The labile C includes oxidisable C (with KMnO4), microbial biomass C (soil carbohydrates) and soil fauna exudates (polysaccharides). Its half-life period is from a few hours to a few days. The non-labile C includes aggregate C and its turn over time is from a few months to a few years while the recalcitrant (stabilised C) includes humic fractions and charcoal C having the turn over time of hundred years. Thus fractionation of SOM is carried out on the bases of humic substances, dissolved organic C, natural C13 abundance, microbial biomass C and ease of oxidation of C. The latter method provides qualitative characterisation of soil C.

Introduction

The soil microbial biomass is an important component of the soil organic matter that regulates the transformation and storage of nutrients. It is a labile component of the soil organic fraction containing 1 to 3% of the soil carbon and up to 5% of the total soil N. The microbiologically mediated processes affect ecosystem functions associated with nutrient cycling, soil fertility, global C change and soil organic matter turnover. The size and activity of the soil microbial biomass must be assessed to fully understand nutrient flux in managed and natural ecosystems.

Soil microbial biomass estimations are useful in investigations that compare temporal nutrient fluctuations along natural and perturbed gradients. The effect of tillage, crop rotations and soil type on organic carbon and nutrient turnover can be assessed by following nutrient pools and activity associated with the soil microbial biomass.

Introduction

Demonstration of biological nitrogen fixation is usually accomplished by estimating the total nitrogen through use of some modification of the Kjeldahl procedure. This technique is accurate and reliable whenever a medium initially low in nitrogen is employed.

Principle

The dried organism is digested with sulphuric acid. Organic and nitrate nitrogen is converted to ammonium sulphate and the ammonia gas is distilled into boric acid forming ammonium borate making weak boric acid alkaline. The ammonium borate is back titrated with standard sulphuric acid until the reaction mixture changes its colour from green to pink due to formation of ammonium sulphate. The standard acid used in back titration of ammonium borate is a measure of nitrogen content of the organism.

Introduction

The major biogenic gases, which contribute to global warming, are carbon dioxide, methane and nitrous oxide. Out of these, methane is the most important gas because its thermal absorption is 30 times greater than carbon dioxide, though its atmospheric concentration is about 200 times less than carbon dioxide. Atmospheric measurements of greenhouse gases indicate that methane concentration had increased by 1 per cent annually to 1.7 ppm (by volume) during the last decade. The steady increase of atmospheric methane concentration in the past 200 years has attracted much attention.

Flooded rice soils provide an optimum environment for methane production and emission. Flooding a soil creates essential redox potential, anaerobic decomposition of organic matter and stabilizes the soil pH near neutral, thus makes the congenial environment for methane emission.

Rice is the world’s most important food crop

Introduction

The enzyme nitrogenase is produced in all N₂-fixing systems. The activity of nitrogenase enzyme relates to the biological nitrogen fixation, which can be determined directly by measurement of fixation product, ammonia and the further products of its assimilation. The activity can also be measured indirectly by measuring the ability of nitrogenase to reduce the number of substrates other than N₂. Substrates such as nitrous oxide (N₂O), azide ion (N₃^- ), cyanide (CN^-) and isocyanide (NC^-) are reduced and the requirements for ATP and reductant are similar to those of N₂ fixation. The reduction of protons to molecular hydrogen has been used to measure the nitrogenase activity.

Dilworth (1966) and Schollhorn and Burris (1966&1967) observed the inhibitory effect of Acetylene (C₂H₂) on N₂ fixation by extracts of Clostridium pasteurianum. Dilworth (1966) further observed by mass spectrometry that the C₂H₂ was reduced to C₂H₄. Both gases are readily measured at very low concentrations by gas chromatographic techniques.

Introduction

All biological reactions in soil are catalyzed by enzymes. Soil enzyme activities are believed to indicate the extent of specific processes in soil and in some cases, can act as indicators of soil fertility. Biological oxidation of organic compounds is generally a dehydrogenation process and there are many dehydrogenases that carry out the following reaction:

XH₂ is an organic compound and is a hydrogen donor and A is a hydrogen acceptor. These systems are integral part of the microorganisms, so dehydrogenase activity can be correlated with active population.

Principle

Measurement of dehydrogenase activity involves determination of Triphenyl formazan (TPF) produced by the reduction of Triphenyl tetrazolium chloride (TTC). TTC is a redox indicator, a yellow coloured water soluble salt which possesses the property of being easily transformed into, methanol soluble formazan (intensely coloured, water insoluble) by reduction.