Biotechnological Applications of Microbes in Food Technology, Environment and Their Limitations

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17/12/2015
Topic: Biotechnological
Applications of microbes
Microbial Biotechnology
Dr. Amjad Hassan
M Saad Iqbal
SP13-BTY-006

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Biotechnological Applications of Microbes in Food
Technology, Environment and Their Limitations
Food Technology Preparation of Fermented Foods
Microbial fermentation is essential to production of wine, beer, bologna, buttermilk, cheeses,
kefir, olives, salami, sauerkraut, and many more. The metabolic end products produced by the
microorganisms flavor fermented foods. These organisms are also of particular importance in the
food fermentation industry because they produce peptides and proteins (bacteriocins) that inhibit
the growth of undesirable organisms that cause food spoilage and the multiplication of foodborne
pathogens.
Nisin
Nisin, an antimicrobial peptide produced by strains of Lactococcus lactis, is widely used as a
preservative at low concentrations (up to 250 ppm in the finished product) primarily in heat-
processed and low pH foods. Nisin inhibits the growth of a wide range of Gram-positive bacteria
but is not effective against Gram-negative bacteria, yeasts, and molds. The antibacterial activity
of nisin is the combined outcome of its high-affinity interaction with lipid II at the outer leaflet
of the bacterial cytoplasmic membrane and permeabilization of the membrane through pore
formation. Nisin is designated as a Generally Regarded as Safe (GRAS) food preservative in the
United States and in many other countries around the world. It is used in many food products.
Lactobacillus Sakei: A Promising Bio-preservative
L. sakei, a psychrophilic lactic acid bacterium, was first isolated from sake.L.sakei cultures is
widely used in the manufacture of fermented meats, and it is used to prevent the growth of
spoilage organisms and pathogens. It is inhabitant of the human gut. Lactobacillus acidophilus is
the permanent members of the human gastrointestinal tract. These organisms are called probiotic
species and stimulate the immune response and suppress the growth of potentially pathogenic
bacteria. It is recently found that the genome of L. sakei 23K is 43% identical to L. acidophilus.
The L. sakei genome codes for four proteins that are involved in cell–cell interaction and in
binding to collagen exposed on the surface of meat. Two other gene clusters functions to produce
surface polysaccharides that may contribute to the attachment of bacterium to meat surface. Meat
undergoes autoproteolysis on aging with release of amino acids. L. sakei is auxotrophic for all
amino acids except glutamic and aspartic and thus the meat surface is an excellent ecological
niche. L. sakei takes up both heme and iron from the meat.The competition for iron is important
factor in the ability of L. sake to exclude other organisms from the meat surface.
Monensin
Monensin is the most widely used compound fed to cattle to increase feed efficiency. Monensin
is produced by the bacterium Streptomyces cinnamonensis. In the anaerobic environment,

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ruminal microorganisms generate the energy and nutrients for their growth by fermenting
carbohydrates and proteins. The resulting products i-e volatile fatty acids and microbial protein,
serve as the sources of energy and nutrients for the cow. The major end products of the
fermentative metabolism of the Gram-positive bacteria in the rumen are acetate, butyrate,
formate, lactate, hydrogen, and ammonia. The methanogenic bacteria in the rumen are not able to
use complex organic compounds. Gram-positive ruminal bacteria are more sensitive to monensin
than are Gram-negative ones. In short, monensin modulates ruminal fermentative metabolism by
selective inhibition of the metabolic activities of particular groups of bacteria.
Single-Cell Protein
The term single-cell protein, or SCP, describes the protein-rich cell mass derived from
microorganisms grown on a large scale for either animal or human consumption. SCP has a high
content of protein containing all the essential amino acids. Microorganisms are an excellent
source of SCP because of their rapid growth rate, their ability to use very inexpensive raw
materials as carbon sources, and the uniquely high efficiency, expressed as grams of protein
produced per kilogram of raw material, with which they transform these carbon sources to
protein. In spite of these advantages, only one SCP product approved for human consumption
has reached the market. This product is “mycoprotein,” the processed cell mass preparation from
the filamentous fungus Fusarium venenatum.
Environmental Applications of Microorganisms
It include Bioremediation, biomining, and microbial desulfurization of coal are other large-scale
processes in which important positive environmental outcomes are achieved by directly
exploiting the combined metabolic capabilities of naturally occurring communities of
microorganisms.
Wastewater Treatment
BOD (Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed (i.
e., demanded) by aerobic biological organisms to break down organic material present in
a given water sample at certain temperature over a specific time period)
Living organisms consist of about 70% water. A human being consume an average of 1.5L/day
to survive. Fresh water represents only about 2.5% of the water on the planet. Wastewater
originates from four primary sources which are sewage, industrial effluents, agricultural runoff,
and storm water and urban runoff. Primary treatment of sewage consists of removal of suspended
solids. The secondary treatment of sewage reduces the biochemical oxygen demand. This can be
done by lowering the organic compound content of the effluent from the primary treatment
through microbial oxidation by an incompletely characterized community of microorganisms in
“activated sludge.” Bacteria of Zoogloea species play an important role in the aerobic
secondary stage of sewage treatment. These organisms produce abundant extracellular
polysaccharide and, as a result, form aggregates called flocs. Such aggregates efficiently

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adsorb organic matter, part of which is then metabolized by the bacteria. The flocks settle out
and are transferred to an anaerobic digester, where other bacteria complete the degradation of the
adsorbed organic matter. The microbial communities in a water treatment plant convert organic
carbon to carbon dioxide, water,andsludge convert some80%of the ammonia and nitrate to
molecular nitrogen remove some soluble phosphate through incorporation into the sludge, either
as polyphosphate granules within bacterial cells or as struvite (crystalline MgNH4PO4) and
remove pathogenic bacteria. Wastewater treatment consumes energy but converts much of the
ammonia and nitrate to nitrogen gas, and a significant amount of the phosphate remains in the
effluent.
Bioremediation
Bioremediation depends on the activities of living organisms to clean up pollutants dispersed in
the environment. Physical or chemical treatments, such as vaporization, extraction, or adsorption,
relocate rather than remove pollutants. bioremediation is generally inexpensive and causes little
disturbance to the environment. Naturally occurring consortia, frequently dominated by bacteria,
have the capacity to degrade a wide spectrum of environmental pollutants.
Biomining: Heavy Metal Extraction Using Microorganisms
Biomining utilizes naturally occurring prokaryotic communities. Here, microorganisms are used
to leach metals, principally copper but also nickel and zinc, from low-grade sulfide- and/or iron-
containing ores. The process exploits the energy metabolism of various acidophilic
chemolithoautotrophs that utilize inorganic compounds as energy sources and CO2 as the source
of carbon. These organisms use either ferrous iron or sulfide as an electron donor and oxygen as
an electron acceptor with the formation of ferric iron or sulfuric acid. In the first case, the
subsequent reaction of Fe3+ with insoluble metal sulfides yields soluble metal sulfates; in the
second, metal sulfides are oxidized directly to metal sulfates. The metals are readily recovered
from the leachate by electrolytic procedures, and the residual solution is recycled. Gold is inert to
microbial action.
Microbial Desulfurization of Coal
Coal contains substantial amounts of sulfur, both in pyrite (FeS2) and in organic sulfur
compounds (thiophene derivatives). The composition of coal varies considerably depending on
the source. For example, Texas lignite coal contains 0.4% pyrite S and 0.8% organic S, whereas
Illinois coal contains 1.2% pyrite S and 3.2% organic S, by weight. When coal is burned, most of
this sulfur is converted to SO2. The SO2 combines with moisture in the atmosphere to form
sulfurous acid (H2SO3), a major component of acid smog and acid rain.
Fungal Removal of Pitch in Paper Pulp Manufacturing
Treatment of wood with certain white rot fungi to degrade certain wood extractives before
pulping substantially decreases the toxicity of pulp mill effluent toward aquatic organisms.

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Compounds that are extractable from wood with organic solvents make up between 1.5% and
5.5% of the dry weight of softwoods and hardwoods. These compounds, called wood extractives,
consist mainly of triglycerides, fatty acids, diterpenoid resin acids sterols, waxes, and sterol
esters. Resin acids are present in most softwoods but are generally absent or are minor
components in hardwood species. During wood pulping and refining of paper pulp, the wood
extractives are released, forming colloidal particles commonly referred to as pitch or resin. These
colloidal particles form deposits in the pulp and in the machinery. These deposits can cause mill
shutdowns and various quality defects in the finished paper products. Moreover, the resin
constituents in pulp mill effluent show acute toxicity toward fish and aquatic organisms
Basidiomycete fungi and Ophiostoma species colonize living and recently dead wood. Many of
the species in this genus are referred to as sap-staining or blue-staining fungi because they stain
colonized wood. To avoid this problem, a commercial fungal product, Cartapip, utilizes an
“albino” strain of Ophiostoma piliferum. When applied to wood chip piles, this fungus has been
particularly effective in degrading triglycerides and fatty acids in both softwoods and hardwoods.
but only partially effective in the removal of other pitch-forming compounds (sterols, sterol
esters, and waxes) or the biotoxic resin acids. Moreover, the effluent biotoxicity was reduced 11-
to 14-fold compared with untreated controls. A number of white rot basidiomycete fungi are able
to degrade the sterol esters and waxes. Several different bacteria, isolated by enrichment of pulp
mill effluent, are able to degrade resin acids.
Limitations of Using Microbes in FoodProduction
They are responsible for rotting of food.
They are responsible for tooth decay.
They spread diseases.
They are responsible for food poisoning.
They are sometimes responsible for whooping of plants too.
Many people may not want to eat fungal protein or food that has been grown on waste.
Isolation of the protein grown in huge fermenters.
The protein has to be purified to ensure it is uncontaminated.
Infection the conditions need for it to grow are also ideal for pathogens. Have to make sure
culture isn't infected with wrong organism.
Microbial contamination in food production kills hundreds of people every year. There was
recently a listeria outbreak at a Maple Leaf Foods plant in Ontario, Canada. Lunch meats were
mainly contaminated, and hundreds of people, mainly the old or very young, died from eating it.
Many more than that got very sick. Salmonella, S. Aureus, Campylobacter, E. Coli; all of these
bacterial strains, when they contaminate food, kil many people.

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Limitations of Single Cell Protein:
There are some limitations also, of using microorganisms or microbial biomass as diet
supplement or as single cell protein.
Many types of microorganisms produce some substances which are toxic to the human and also
to the animals. Therefore it has to be made sure that the produced microbial biomass does not
contain any of these toxic substances.
Sometimes the microbial biomass when taken as diet supplement may lead to indigestion
Sometimes the microbial biomass when taken as diet supplement may lead to allergic reactions
in humans.
The high nucleic acid content of many types of microbial biomass products is also undesirable
for human consumption as single cell protein. Sometimes this high level of nucleic acid content
in microbial biomass will lead to kidney stone formation or gout.
The high nucleic acid content of many types of microbial biomass may lead to poor digestibility,
gastrointestinal problem and also some skin reactions in humans.
The possibility of presence of toxins or carcinogenic compounds may lead to some serious health
problems in humans as well as in animal stock.
Single cell protein production is a very expensive procedure as it needs high level of sterility
control in the production unit or in the laboratory.
Single cell protein grown as animal feed on agricultural residues will be beneficial in the future
economy of developing nations.
Limitations of Microbes in Environment Applications
Disease-Inducing Soils
In this type of soil, plant pathogenic microorganisms such as Fusarium fungi can comprise 5 to
20 percent of the total microflora if fresh organic matter with a high nitrogen content is applied
to such a soil, incompletely oxidized products can arise that are malodorous and toxic to growing
plants. Such soils tend to cause frequent infestations of disease organisms, and harmful insects.
Limitations of microbes in Bioremediation

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Bioremediation, although considered a boon in the midst of present day environmental situations,
can also be considered problematic because, while additives are added to enhance the
functioning of one particular bacteria, fungi or any other microorganisms, it may be disruptive to
other organisms inhabiting that same environment when done in situ. Even if genetically
modified microorganisms are released into the environment after a certain point of time it
becomes difficult to remove them. Bioremediation is generally very costly, is labor intensive,
and can take several months for the remediation to achieve acceptable levels. Another problem
regarding the use of in situ and ex situ processes is that it is capable of causing far more damage
than the actual pollution itself.
The process is sensitive to the level of toxicity and environmental conditions in the ground i.e. the
conditions must be conducive to microbial activity e.g. need to consider temperature,pH etc.
Limitation in waste water treatment
The main disadvantage of many anaerobic treatment processes is that they are not good at
removing non-organic pollution within wastewater, such as nutrients or disease-causing micro-
organisms (pathogens).
Limitation in paper pulp production
In enzymaticandfungal method,still triglycerideswere the mainresponsible of pitchproblems.
Limitation in desulfurization of coal
Bacterial treatment was applied to column flotation. An increase of cell density in the microbial
column flotation resulted in the increase of pyrite removal from a coal-pyrite mixture (high
sulfur imitated coal) with corresponding decrease of coal recovery.
What is biomining
What is bioremediation
Microbial Desulfurization of Coal (of microbes only)… 1 line answer (Microbial desulfurization of
coal,by converting the pyrite to ferric sulfate and leaching it out of the coal.)
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