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Home > News Archives > Bug of the month
WISA would like to thank
ERWAT for their contribution towards "Bug of the Month"
1. Spirochetes
 Spirochetes
are a group of gram-negative bacteria distinguished by their
structure and mechanism of motility. They are slender, long
bacteria with flexible, helical shapes. Spirochetes can be
anaerobic, facultative anaerobic or aerobic. Ecologically,
the group is exceptionally diverse, growing in habitats
ranging from mud to the human mouth. Many of these are
harmless saprophytes, while others cause diseases in animals
and humans, namely syphilis and lyme disease.
 2.
Actinopoda
In this
group the Heliozoae are found. These organisms form
globular cells that are surrounded by pseudopodia, which are
as thin as needles and dead straight. The latter are
contractile. They are not used for the movement of the cell
but for catching algae. Organisms that are touched by these
pseudopodia are paralysed and can be subsequently be
consumed, its diameter may vary from 40-100um.
3. Iron bacteria
Iron
bacteria are a diverse group of micro-organisms widely
distributed in nature.
 They
are found in fresh and salt waters, in soil and on desert
rock surfaces. Iron bacteria are morphologically and
physiologically heterogeneous, having the ability to
transform significant amounts of iron into obnoxious
slimes. However iron bacteria are not the only producers of
bacterial slimes. The large amount of brown slime
produced will have a reddish tinge and an
unpleasant odor to drinking water, and may be unsuitable for
domestic and industrial use. Iron
 bacteria
metabolize reduced iron present in their aqueous habitat,
and deposit it in the form of hydrated ferric oxide on or in
their mucilaginous secretions.
Iron may be
obtained from the pipe itself if it is made of iron or from
the water within the pipe. Iron bacteria do not normally
cause diseases to humans or animals but they are nuisance
micro-organisms. They can cause
severe fouling problems in wells, treatment plants and
distribution systems.
4. Staphylococcus
Aureus
The genus
Staphylococcus consist of gram- positive cocci, usually
found in irregular clusters, within which pairs and tetrads
are commonly seen.
S. Aureus is
the most important clinical member of this genus.
The presence of
this bacterium or its enter toxins in processed foods or on
food processing equipment is generally an indication of poor
sanitation. S. Aureus can cause severe food poisoning.
 It
has been identified as the causative agent in many food
poisoning outbreaks and is probably responsible for even
more cases in indivi duals
and family groups than the records show.
Foods are examined for the presence of
S. aureus and/or its enter toxins to confirm that S. aureus
is the causative agent of food borne illness, to determine
whether a food is a potential source of "stash" food
poisoning, and to demonstrate post-processing contamination,
which is generally due to human contact or contaminated
food-contact surfaces. Its presence is also tested in animal
feed water.
5. Biofilms
Certain
microorganisms can irreversibly adhere to a submerged
surface and differentiate to form a complex, multicellular
structure called a biofilm.
The surface
may be inert, nonliving material or living tissue. A
biofilm consists of microbial cells (algal, fungal,
bacterial) and the extra cellular biopolymer these cells
produce. Bacteria attach to surfaces by proteinaceous
appendages referred to as fimbriae. Once a number of
fimbriae have "glued" the cell to the surface, detachment of
the organism becomes very difficult. Then the organisms
begin to produce extra cellular polymers (sometimes called
"slime") that facilitate adhesion and provide a structural
matrix. The slime consists primarily of polysaccharides and
water. The amount of biopolymer produced can exceed the
mass of the bacterial cell by a factor 100 or more. The
biofilm structure provides a favourable protective
environment for the survival of the cells of the organism.
In industry biofilms are also notorious for causing pipe
plugging and corrosion.
Biofilms
happily colonize many household surfaces, including toilets,
sinks and cutting boards in the kitchen and bath.
Ineffective cleaning may increase the incidence of illness
associated with pathogenic organisms
coming from
these surfaces.
 Biofilms
on the surfaces of catheters, medical implants, wound
dressings or
other types of medical devices are often responsible for
infections. Biofilms are very tenacious and highly
resistant to antibiotics. Besides, detachment of the
biofilm from the device may result in infection. Research
has shown that virtually all indwelling catheters are
colonized by micro-organisms embedded in a biofilm matrix.
6. Sulfur Bacteria
in Water Supplies
Bacterial contamination of a water
supply doesn't always mean 'health hazard'. Some types of
bacterial contamination are more annoying than harmful.
Sulfur bacteria are one of the most common bacterial
contaminants that well owners face. Sulfur bacteria are
particularly harmful, at least not at the levels usually
seen in well systems. However, they can be incredible
nuisances. There are two categories of sulfur bacteria:
sulfur oxidizers and sulfur reducers.
* Sulfur-oxidizing
bacteria
Sulfur-oxidizing
bacteria produce effects similar to those of iron bacteria.
They convert sulfide into sulfate, producing a dark slime
that can clog plumbing
* Sulfur-reducing
bacteria
Sulfur-reducing
bacteria (SRBs) live in oxygen-deficient environments. They
break down sulfur compounds, producing hydrogen sulfide gas
in the process. Hydrogen sulfide gas is foul-smelling and
highly corrosive.
Of the two
types, sulfur-reducing bacteria are the more common. The
most obvious sign of a sulfur bacteria problem is the
distinctive "rotten egg" odor of hydrogen sulfide gas. As
with odors caused by iron bacteria, the sulfur smell may
only be noticeable when the water hasn't
been run for
several hours. In some cases, the odor will only be present
when hot
 water
is run; this could indicate that SRBs are building up in the
water heater.
Blackening of
water or dark slime coating the inside of toilet tank may
also indicate a sulfur bacteria problem. Iron bacteria and
sulfur bacteria contaminations are often difficult to tell
apart because the symptoms are so similar, To complicate
matters, SRBs often live in complex symbiotic relationships
with iron bacteria, so both types may be present.
Fortunately, both types of bacteria can be treated using the
same methods.
7. Gram stain:
Clostridium perfringens
Clostridium
perfringens is an anaerobic, Gram-positive,
 <http://vm.cfsan.fda.gov/cgi-bin/bbbglos?Gram-Positive=Rods>
spore-forming rod (anaerobic means unable to grow in the
presence of free oxygen). It is widely distributed in the
environment and frequently occurs in the intestines of
humans and many domestic and feral animals. Spores of the
organism persist in soil, sediments, and areas subject to
human or animal faecal pollution. Perfringens food
poisoning is the term used to describe the common foodborne
illness caused by C. perfringens. Ingesting food
contaminated with Type C strains also causes a more serious
but rare illness.
The toxin
causes necrosis of the surrounding tissue (Clostridia my
necrosis destroys muscular tissues).
The
bacteria produces gas which leads to a bubbly deformation of
the infected tissues. C. Porringers is capable of
necrotizing intestinal tissues and can release an
enterotoxin that may lead to severe diarrhea. Treatment of
infection can consist of penicillin G (to kill the
organism), hyper baric oxygen (oxygen delivered at increased
pressure produces an increase in the amount of oxygen being
carried by blood. This results in more oxygen being
delivered to the organs and tissues in the body. This
improves the benefits of certain antibiotics, activates
white blood cells to fight infection, and promotes the
healing process in chronic wounds, and administration of an
antitoxin.)
8. Ascaris
Lumbricoides
 Ascaris
Lubricoides is one of the largest and most common parasites,
which infects humans. It is estimated that one billion
people worldwide are infected with the parasite. The
infection occurs in all age groups, although children seem
to be affected more severely than adults. The adult worm
ranges in length from 20 to 45 cm and measures 5 mm in
diameter, the female being larger than the male. Infection
with this intestinal roundworm is generally associated with
conditions of poor hygiene or sanitation. Humans become
infected by ingesting food or water contaminated with faces
containing Ascaris eggs. The disease (known as ascariasis)
is diagnosed by microscopic detection of Ascaris eggs in a
faecal smear. A number of medications are effective in
killing adult worms, including mebendazole and pyrantel
pamoate.
9. Carchesium
 This
organism is a sessile ciliate characterised by the fact that
the surface of their cells is completely or partly covered
with cilia (short hair-like structures). Around the "mouth"
the cilia are often grouped in a certain way. This causes
the surrounding liquid to flow and allow them to "fan" their
food towards them.
Carchesium
has a bell-shaped body projected on a stalk containing a
myoneme (muscle) allowing the organism to contract. The
organism is attached by the floc by means of this stalk.
This protozoa feed almost entirely on dispersed bacteria and
therefore help to increase the clarity of the water.
10. Tintinnidium
 Our
bug of the month is Tintinnidium. This organism is found in
activated sludge on most of ERWAT's works. Tintinnidium is
a ciliate. Its body is housed within a cup-shaped Iorica of
chitnoid nature, which it secretes. It is one of the more
advanced forms of ciliates, in which body cilia have been
reduced to a few rows in the region of the mouth and
function mainly in feeding. Cilia are little hair-like
structures, which move in a brush-like motion drawing in
food etc. the organism falls under the sub-order of
Oligotricha and it possesses a gullet (a passage for food
extending from the mouth of the stomach), which is
permanently open.
The organism extends out of this cup
by means of a muscle to feed. It principally feeds on
bacteria but their nutritional requirements are highly
complex and have not yet been fully determined. Not all
bacteria serve as good food for the organism and it has been
found that bacteria, which produce pigments, are toxic to
ciliates. These organisms usually occur singly, but within
the cup, from one to three bodies may be found. The cup
attaches directly to the floc and thus is not readily lost
during wasting.
11. Indicator
Organisms
 Many
human diseases, particularly those of the intestinal tract,
for example cholera, are spread through faecally
contaminated water. As isolation and identification of many
of the disease producing microorganisms is not always
feasible, suitable indicator organisms are used to assess
the sanitary quality of water as well as to detect the
possible presence of enteric pathogens.
The chosen
indicator organisms are total coliforms, faecal coliforms,
faecal streptococci or enterococci. They are suitable as
they are generally present in water containing the
pathogens; survive longer in the aquatic environment; are
relatively harmless and are thus safe to work with and are
easily grown, isolated and identified.
Total coliforms
include species that may inhabit the intestinal tract o
warm-blooded animals, including humans, or occur naturally
in soil, vegetation or water. Though they are relatively
harmless, they are usually present in water containing
enteric pathogens. If water is free of coliforms then it is
safe to assume that the water is free of disease producing
organisms. Faecal coliforms, for example E.coli, are those
coliforms always associated with direct faecal pollution and
the possible presence of enteric pathogens. Some strains of
E.coli, are themselves pathogenic. The total
coliform count may include faecal coliform organisms.
12. Chilodonella
 This
specie is a ciliate, characterized by the fact that the
ventral surface of its cell is covered with cilia. There
are no cilia on the dorsal side. The mouth has a bulge
around it in the shape of a short tube. Around the opening
of the mouth, the cilia are grouped in a certain way. By
movement of the cilia, the surrounding liquid flows in the
direction of this mouth. They feed on bacteria in the
wastewater. By continuous cropping, they keep the bacterial
population in a state of prolonged physiological youth,
increasing their rate of assimilation of organic materials.
Cilia also play a part in the movement
of the cell. Chilodonella glides over the surface of the
flocs. The flap on the front side of the cell curls up when
Chilodonella 'mounts' a sludge floc.
13. Poteriodendron
 Poteriodenron
falls into the protozoan subgroup, Flagellates. These
organisms have hair-like structures called flagella for
locomotion. The cells are approximately 20um in length, are
ovoid in shape and each cell is surrounded by a vase-shaped
lorica. Underneath the lorica is a stalk with which the
complete organism is attached to another cell. In this way,
a colony of Poteriodendron cells is formed.
14. Opercularia sp
This species
has an inverted bell shaped body attached to a stalk, which
attaches to a substrate (floc). It has branched stalks and
usually form colonies. One of its distinguishing
characteristics is a lid from which little hairs project.
The lid opens and the little hairs move, fanning food
 like
bacteria into the mouth area.
Stalked
protozoa (single celled animals) such as the Opercularia sp
are usually dominant in the aerobic wastewater treatment
process.
Seeing as this
type of protozoa are assumed to feed almost entirely on
dispersed bacteria we can deduce that the effluent is
largely dependent on stalked protozoa for clarity.
Organisms like this supply invaluable information when
analyzing water treatment plants.
15. Salmonella spp
 Salmonella
is arod - shaped flagellated, facultatively anaerobic
bacterium. There is awide spread occurrence in animals,
especially in poultry and swine. Environmental sources of
the organism include water, soil, insects, factory surfaces,
kitchen surfaces, animal and human
faeces, raw
meats, raw poultry and raw sea foods. At times salmonella
is found in sludge amended soil. This suggests that sludge
which id found in sludge amended soil. This suggests that
sludge which is to be used in amending soil for growing food
crops may need further treatment, such as composting to
reduce its growth. Salmonella causes gastroenteritis and
some causes enteric fever.
16. Blespharisma
 Blespharisma
are characterized by the cilia which cover their outer
surface. Around the 'mouth' of the organism the cilia are
often arranged in a particular manner to facilitate the flow
of liquid medium in which it lives into the mouth. This
organism lives off bacteria and large organic particles.
Cilia also
plays a role in the movement of Blespharisma through the
medium. Its elongated body of some 80 to 400 mm, is
completely covered with cilia and is hardly flexible. Near
the somewhat submerged 'mouth' the cilia occur in the shape
of the membranes. The organism often has a light pink hue.
17. Oligochaetes
Commonly known
as worms, these are the largest organisms observed in
activated sludge using a microscope. They diameter of
approximately 0.1 mm and length to a maximum of 10 mm. They
are able to consume sludge flocs
 or
particles of flocs. A significant fraction of the consumed
organic matter is converted to energy. They have a
generation time of a few days and worm blooms can cause a
reduction in sludge production. They are not observed at
low sludge loading levels.
Sludge
containing many worms usually originates from treatment
plants with a sludge load of ca. 0.1 kg BOD / kg MLSS a day
in which the effluent is pre-settled. Worms will not
survive long periods (days) without oxygen, which is a
condition that can therefore be used as a control option.
18. Nocardis spp
 This
bacteria is commonly observed in activated sludge. It causes
activated sludge to foam, not bulk, because it is too short
a filament to interfere with sludge settling. Nocardial
foam occurs as a thick, stable, brown foam or scum, on the
aeration basin and final clarifier surfaces. The foam
stability results from the filaments, which extend beyond
the floc surface interlocking physically. Although this
foam occurs in plants treating domestic industrial as well
as mixed wastes, its proliferation has been linked to waste
rich in grease, oil or fat. Should the foam escape into the
effluent, the increase in suspended solids may compromise
disinfection.
19. Coliforms
The coliform group of organisms is
suitable as indicators as these are common inhabitants of
the intestinal tract, both of humans and warm-blooded
animals and is generally present in the intestinal tract in
large numbers.
When excreted
into the water environment, coliforms persist for a period
of time, but are not able
to continue
growing, and thus, ultimately die off. They are more
resistant than the intestinal pathogens, which means that
the coliforms are no longer present, it may be assumed that
the intestinal pathogens have also disappeared.
  
20. Nematodes
Free-living
nematodes are terrestrial macro invertebrates that are
capable of living in fresh water habitats. Because soils
are infested with free-living nematodes, these macro- invertebrates
enter wastewater treatment plants on a constant basis and
may be present in aerobic treatment processes in large,
though often highly variable, quantities. These Nematodes
include eelworm, nemas, roundworm and threadworm. They are
microscopic in size, measuring 0.5 to 3.0 mm in length and
0.02 to 0.05 mm in width.
Most species
are similar in appearance. Although they may appear to be
segmented due to the thickening of the cuticle or epidermis,
nematodes are in fact non-segmented. They have cylindrical
bodies with tapering ends and are not good swimmers, moving
through the water / moving along in activated sludge.
 Nematodes
found in fresh water or wastewater originates from soil
run-off. They thrive in aerobic environments where food
supplies are abundant and when DO concentrations are high.
Their diet consists of algae, aquatic plants, bacteria,
decaying organic materials, other nematodes, protozoa and
rotifers. Aerobic treatment processes in particular the
activate sludge and trickling filter processes, are
continuously seeded with nematodes that are not removed in
the primary clarifier.
 They
perform several supportive roles in the overall biological
stabilization of wastewater, sludge and sludge amended
soils, with the most important of these roles being
performed during the trickling filter process. During this
process, they break off pieces of the biofilm that coats the
filter beds, thereby preventing excessive growth of the
biofilm and clogging of the filter. At the same time, they
keep the biofilm porous enough for oxygen to penetrate the
system, thus increasing microbial activity and the
degradation of organic waste.
 21.
Linotus
The cells of
this organism are bottle shaped. The neck and the remaining
part of the ells are of the same length about 50um. The
presence of cilia is restricted to the dorsal side. The
stout neck region bends forward towards the dorsal side.
22. Euplotes
 This
organism forms ovoid shaped cells and its length varies from
80 120um. On the dorsal side 6 ridges are present. The
ventral surface is flattened. Separate cilia do not occur
but there are however some cirri are usually clearly
visible. The organism has well developed membranes in the
peristomal area. Euplotes resembles Aspidisca, but the
latter ciliate is clearly smaller than Euplotes.
23. Amoeba
These are unicellular organisms
belonging to the Subphylum, Sarcodina. Its primary
characteristic id the possession of the pseudopodia, which
are retractile processes that serve as organelles,
locomotion and feeding.
Amoeba is
typically found in wastewater treatment plants belong to one
of two groups: Naked - without a shell (of which fifteen
species have been recorded at a treatment plants) and
Testate - with a shell. Amoeba that occurs in wastewater
feed primarily on bacteria. As a result of an inefficient
chase and capture feeding mechanism, they require a high
prey density and are thus the predominant protozoa when
foods to micro – organism conditions prevail. By feeding on
the free-swimming bacteria they assist in reducing the
turbidity of the water.
Some species of
amoeba feed on other animals. Entamoeba histolytic is a
potentially harmful human parasite as it often produces
severe amoebic dysentery, which may be fatal. It is
prevalent when adequate sanitation and proper personal
hygiene is lacking. This single-celled parasite can exist
outside the host in water, soil and on food in the form of a
cyst.
  
24. Cholera
 The
disease is contracted through the ingestion of water or food
contaminated by the faeces of an infected individual. Some
of the vibruos may survive the acidity of the stomach and
set up a focus of infection in the small intestine. To
which is normally relatively free of bacteria because of the
effective clearance mechanism of peristalsis and mucus
secretion. Cholera is endemic or epidemic in areas with
poor sanitation with seven pandemics recorded to date.
25. Filamentous
Bacteria/Microthrix Parvicella
This bacteria is medium in length and has non-motile
filaments of 100-400 um. The irregularly coiled filaments
have no branching and no cell septa and its cells are square
(o.6 x 0.8 um). Filaments are found in spaghetti-like
tangles within the floc structure causing open, lacy,
diffuse floc or in loose patches free in the bulk solution.
The filament staining is strongly Gram positive or Gram
variable when in the floc structure and Neisser negative
with Neisser positive granules observed frequently. Short
clear spaces ma y
occur in the filament. It is usually easy to identify due
to its staining characteristics. Intracellular PHB granules
may give beaded effect. It has no sulfur granules and no
attached growth or sheath present. It is a common cause of
foaming.
This filament is usually found in environments where there
is low F/M (0.05-0.2 lbs BOD) and with a long MCRT (10-40
days). High wastewater grease and fat content may also be a
cause to this. It is found more commonly in the colder
climates in the north.
Municipalities that have high grease in lift stations can
have high problems with this filament as well as Nocardia.
The F/M can
be changed by increased sludge wasting, changing from
complete mix to plug flow or use of a selector. Extensive
chlorination or RAS chlorination should definitely be used.
Reducing sludge age helps. If possible increase grease and
fat control on the influent if applicable.
26.
Haliscomeenobacter hydrossis
 Halicomenobacter
hydrossis can best be characterized by the following term
“it’s like finding a needle in a haystack”. It really is
finding a
 needle.
H. hydrossis has one of the smallest widths of any of the
filamentous bacteria, 0.5 um. It is a rather straight, with
some curvature, filament usually extending to a length of 20
-100 um. Very rarely does it have any attached growth. It
is Gram negative and Neisser negative.
H.hydrossis is hard to find because of
its diminutive size. It is straight and thin like a
needle. Very rarely does it have attached growth.
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