Downstream processing is primarily concerned with the initial separation of the bioreactor medium into a liquid phase & a solid phase and subsequent separation, concentration & purification of the product. Chemical engineering principles play a vital role here, as well in terms of designing and operation of the separation systems. Downstream processing costs can be as high as 60 - 70% of the selling price of the product as exemplified by the plant Eli Lilly built to produce human insulin. Over 90% of the 200 staff are involved in the recovery processes. Downstream processing represents a major part of the overall cost of most processes, but is also the least glamorous aspect of biotechnology. Improvements in downstream processing will benefit the overall efficiency and cost of processes and will make the biotechnology competitive to the conventional chemical processes. Downstream operations can play catch-up through conventional capacity-expanding strategies, for example by scaling up downstream equipment, employing multiple controllers for more rapid cleaning between steps, running fewer purification cycles (by scaling up column dimensions) or using media with higher throughput or binding capacity. Each solution has its benefits, as well as costs.

In recent years, increasing attention has been paid to the use of renewable biomass for energy production. Anaerobic biotechnological approaches for production of liquid energy carriers (ethanol & a mixture of acetone, butanol & ethanol) from biomass can be employed to decrease environmental pollution & reduce dependency on fossil fuels. There are two major biological processes that can convert biomass to liquid energy carriers via anaerobic biological breakdown of organic matter, ethanol fermentation and mixed acetone, butanol, ethanol (ABE) fermentation. The specific product formation is determined by substrates and microbial communities available, as well as the operating conditions applied.

The starting point for enzyme production is a vial of a selected strain of microorganisms. They will be nurtured and fed until they multiply many thousand times. Then the desired end-product is recovered from the fermentation broth and sold as a standardised product. A single bacteria or fungus is able to produce only a very small portion of the enzyme, but billions microorganisms, however, can produce large amounts of enzyme. The process of multiplying microorganisms by millions is called fermentation. Fermentation to produce industrial enzymes starts with a vial of dried or frozen microorganisms called a production strain. The production strain is first cultivated in a small flask containing nutrients. The flask is placed in an incubator, which provides the optimal temperature for the microorganism cells to germinate. After the seed fermentation, the cells are transferred to a larger tank, the main fermenter, where fermentation time, temperature, pH and air are controlled to optimise growth. When this fermentation is complete, the mixture of cells, nutrients and enzymes, called the broth, is ready for filtration & purification. The enzymes are extracted from the fermentation broth by various chemical treatments to ensure efficient extraction, followed by removal of the broth using either centrifugation or filtration. Followed by a series of other filtration processes, the enzymes are finally separated from the water using an evaporation process. After this the enzymes are formulated and standardised in a form of powder, liquid or granules.

The application of lactic acid bacteria (LAB) to crops at ensiling to improve silage quality is a common practice. Homofermentative LAB such as Lactobacillus plantarum, Enterococcusfaecium & Pediococcus spp. are used, with the goal of providing a faster fermentation, lower final pH values, raised lactate:acetate ratios, lower ethanol & ammonia nitrogen concentrations, and improved dry matter recovery . Recently, a heterofermentative LAB inoculant species, Lactobacillusbuchneri, has become available commercially and produces high concentrations of acetic acid in silage, which inhibits fungi & thus preserves silages susceptible to spoilage on exposure to air. Many studies have shown the beneficial effects on ruminant performance of feeding them with silages inoculated with lactic acid bacteria (LAB). These benefits might derive from probiotic effects.

Starter culture were prepared by inoculating the selected strain in 100 ml GM medium and incubated on a shaker (150 rpm) at 37ºC for 48 hrs. The starter culture containing 1.5x104 viable cells/ml was inoculated (10%) to GM medium supplemented with various nutrients compositions by varying carbon sources & concentrations (glucose, fructose or acetate at 0-6 g/l), nitrogen sources & concentrations ((NH4)2SO4, NH4NO3 & NH4Cl at 0-0.2 g/l), mineral salts (KH2PO4, K2HPO4, MgSO4, CaCl2 & MnSO4 at 0-1 g/l) and vitamin (nicotinic acid, r-aminobenzoic acid, thiamine each at 0-1 mg/l, biotin at 0-0.01 mg/l or no addition of vitamin). The cells were cultivated on a shaker (150 rpm) at 37ºC under aerobic-dark condition. Growth (in term of dried cell weight, DCW), pH and PHB content were determined at the end of cultivation (60 hrs).

Fermentation is the term used to describe any process for the production of a product by means of the culture of microorganisms or cells. Fermentation is often thought of as the first step in many biotechnology processes. Organic biological molecules, microbes, therapeutics, enzymes, antibiotics and vaccines are all produced using fermentation. Fermentation covers a wide range of subjects from the biological point of view, such as care & maintenance of bacterial strains, conditions affecting the growth of bacteria, modelling of bacterial growth pattern. It also tackles the hardware angle, including the design & construction of a fermenter & the use of probes to measure the state of a culture. Although the main emphasis is on organisms, McNeil and Harvey also describe fermentation in animal cells - a nice touch. Contract fermentation & cell culture services offers custom fermentation services for the production of microbial cells & their products in volumes up to 375 liters under BSL2 containment. Tissue culture facilities are also available for the production of various animal cells, such as HeLa S3's and 293 cells for adenovirus propogation.

Lignocellulosic materials represent a large and inexpensive resource because they cannot be digested and therefore do not compete as food. However, their inability do be digested makes them difficult to convert to fermentable sugars. Indeed, the fermentation of sugars derived from lignocellulosic matter has proven to be more of a process design and operating challenge than traditional sugar or starch-based processes. The bioconversion of lignocellulosic biomass to ethanol is a complicated series of strongly interdependent process steps. In the enzymatic hydrolysis of cellulose to obtain water-soluble sugars, the enzyme source is the aqueous culture mass obtained in an enzyme preparation step by cultivating an aqueous nutrient medium in the presence of a cellulosic material. A cellulolytic microorganism is capable of elaborating a cellulolytic enzyme complex which can degrade native cellulose. No separation is made of any component of the culture mass. Such use of the culture mass as the enzyme source not only eliminates processing steps to separate the enzyme, but also results in increased hydrolysis rates and yields of the desired water-soluble sugars in the hydrolysis of cellulose