Microbial Applications:

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Microbial Applications

• Sustainable and Clean Technology

wstafford_at_uwc.ac.za
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Industrial clean technology

• Industrial process can be divided into a number
  of basic stages- extraction and supply of raw
  materials processing of the raw materials/
  production of product use of the product and
  disposal of the product.
• The objectives of a sustainable industrial
  process are as follows
• low consumption of energy
• low consumption of non-renewable raw materials
• eliminate waste at all stages (reduce, re-use,
  recycle)

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Microbial applications

• Useful product- bulk and fine chemicals (e.g
  ethanol, acetone, biosurfactants and bioplastics)
  
• Supply of clean raw materials
• Recovery of metals (biomining and bioleaching)
• Recovery of wastes (sewage treatment,
  bioremediation, pytoremediation and
  bioaugmentation)
• Agricultural Biotechnology (GMO food crops)
• Biomarkers, Bioindicators and Biosensors

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Desulphurisation of oil

• The burning of fossil fuels, petrol, diesel, and
  coal, releases sulphur oxides into the atmosphere
  which are the principal cause of acid rain
• Crude oil contains between 0.05 and 5.0 sulphur
  compounds. Majority (70) of the sulphur in
  crude oil is found as dibenzothiophene (DBT) or
  substituted DBT.
• Chemical desulphurisation is carried out by
  decomposition with hydrogen at high temperature
  and pressure (1035-20 700 kPa and 230-455C)
• Biological desulphurization is possible as a
  number of microorganisms have been isoloated
  which can degrade DBT and include Rhodococcus
  spp., Agrobacterium, Gordona, Klebsiella,
  Nocardiaglobelula, Paenibacillus, Pseudonmonas

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Desulphurisation of coal

• Coal is a heterogeneous solid that contains a
  variety of organic and inorganic sulphur
  compounds that will vary with source.

The main organic sulphur compounds in coal are
the DBTs. Inorganic sulphur is mostly as iron
pyrite
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Microorganisms a better option for sulphur
removal?

• Changes in combustion at the power station can
  reduce the emission of sulphur dioxide by
  fluidized-bed combustion. Pulverized coal is
  fluidized by an airstream, which ensures that the
  coal is completely burnt. Limestone is added to
  trap the sulphur as a molten slag. This process
  requires advanced combustion designs and is not
  applicable to all power stations.
• An alternative is to use microorganisms that will
  metabolize the components of coal.

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• The inorganic sulphur in coal can be oxidized by
  chemolithotrophs like Thiobacillus ferrooxidans,
  Thiobacillus thiooxidans, and Sulfolobus
  acido-caldarius, which are responsible for acidic
  mine drainage. Linked to the oxidation of reduced
  iron, T. ferrooxidans generates energy by the
  direct oxidation of iron (II) sulphide to iron
  (I) sulphate
• 2FeS2 7O2 2H2O 2FeSO4 2H2SO4
• Microbial action can also directly convert
  elemental sulphur to sulphuric acid.
• 2S 3O2 2H2O 2H2SO4
• The main organic sulphur compounds in coal are
  the DBTs. The organic sulphur compounds are an
  integral part of the coal matrix and therefore
  are much more difficult to remove than the
  pyrites (enzymic cleavage of CS). Various
  micro-organisms can degrade DBTs Rhodococcus sp.
  (Gray et al., 1996), Pseudomonas spp. TG232
  (Kilbane, 1989), Brevibacterium sp. (McEldowney
  et al., 1993), and Aspergillns niger

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(No Transcript)
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Untreated soil Rhodococcus ECRD-1 treated
soil
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Results Bio-desulphurisation of coal
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Enzymes

• Micro-organisms and enzymes can replace inorganic
  catalysts that are used in the conventional,
  chemical methods. This has several advantages
• Use less energy (lower Ea)
• Reactions can be very specific (stereo
  specificity)
• Reactions are fast and effective to give reduced
  process times
• Produce less toxic waste
• Generally use renewable resources
• We can also use molecular biology methods
  (mutagenesis, gene shuffling and molecular
  evolution) to possibly improve the organism or
  enzyme to the desired task.
• Also, enzymes are now available from
  extremophiles

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Enzymes as stereo-specific catalysts

• Single enzymes are excellent catalysts that can
  perform regio- and stereo-specific reactions.
  Micro-organisms can also be regarded as
  multiple-enzyme containers that can carry out one
  or multiple reactions. One of the best examples
  of the very specific nature of enzymes is the
  production of steroids,

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Industrial applications of enzymes
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Industrial applications of enzymes

• Laundry detergents-addition of lipase, protease,
  and amylase to detergents allowed the use of
  lower temperatures, and the better removal of
  specific stains. There has been continual
  development of enzyme detergents with increased
  activity at low and high temperatures and at
  alkaline pH values.
• Textile industry has used alkaline proteases for
  degumming silk, removing a protein from the
  outside of the silk fibres (Gupta et al., 2002).
  Pectinases used to remove cell-wall components
  from cotton fibres and glucose oxidase used to
  bleach the fibres. Cellulases have been used to
  treat denim garments as an alternative to
  stonewashing in a process known as biostoning
  (Belghith et al., 2001).
• Leather Replacement of the chemical processes by
  enzymes should have considerable advantages.
  Proteases have been used to de-hair hides and
  lipase to remove fat.
• Paper Cellulases have been used to assist
  pulping, and to de-ink paper. Laccase enzymes
  that attack lignin have been used to bleach pulp
  as an alternative to chlorine bleach (Kirk et
  al., 2002).

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Extremophiles

• The microorganisms found in extreme conditions of
  temperature, salt, and pressure belong to the
  domains of Bacteria and Archaea, but the
  majority-are the Archaea.
• Clearly these types of micro-organism will
  contain enzymes that can function under extreme
  conditions. e.g Thermus aquaticus (Taq polymerase
  enzyme for PCR)

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Enzymes from Extremophiles

• (Eichler, 2001 Haki and Rakshit, 2003 Huber and
  Stetter, 1998).

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Developments in Industrial Microbial Applications

• Identify the huge diversity of microorganisms and
  the huge potential of uncharacterized genes and
  gene products (gene identity and function)
• Develop sustainable, renewable technologies using
  microorganisms and their products
• Solve some of the problems of enzyme stability by
  expanding natures repertoire (mutagenesis,
  molecular evolution etc.)