Fish Waste Management: Treatment Methods Based on the Use of Microorganisms - Aquaculture Microbiology and Biotechnology - page 221

a diverse and stable pond community where undesirable species do not
become dominant (Bratvold et al., 1997).
MICROBIAL MATS
Microbial mats are laminated, cohesive microbial communities, composed
of a consortium of bacteria dominated by photoautotrophic cyanobacteria
(also referred to blue-green algae) (Nisbet and Fowler, 1999). Cyanobacteria
are organisms which thrive in environments where extreme fl uctuations
in conditions occur ( http://www.bio.vu.nl/thb/users/vdberg/berg-mat.
html ) . Although microbial mats are trying to grow almost everywhere
almost all of the time, it is only in special places the microbes have the
opportunity to grow the large amounts of biomass comparable to what
was found on early Earth ( http://nai.arc.nasa.gov/students/this_
month/index.cfm ). Most mats stabilise unconsolidated sediments and
grow actively; they can be several millimeters to a few centimeters thick,
and develop along a variety of microgradients established between water
and sediments. The formation of microbial mats is an extremely ancient
biological phenomenon, as communities of different types of microbes
covered the early Earth (Guerrero et al., 2002).
TREATMENT OF FISH WASTE WITH THE USE OF
MICROORGANISMS
Aspergillus sp.
Wheat bran, minced fresh sardines and Aspergillus awamori spores were
mixed and kept in a ventilated incubator for 5 d at 40°C. A decrease in
crude protein, crude fat and nitrogen-free extracts up to 2.6, 22.2 and 25.7%,
respectively, were recorded. On the contrary, an increase up to 16.1% in
crude fi bre content was reported; thus indicating that crude fi bre may be
synthesised by Aspergillus awamori . During fermentation glucoamylase
(9.71 U), α-glucosidase (0.21 U), α-amylase (21.69 U) and acidic protease
(17778 U), were formed. In addition, an increase in dry matter digestibility
was mentioned regardless of the levels of fi shmeal, and it was signifi cant
at 5 and 10% (Yamamoto et al . , 2005).
Different combinations of the bonito's body parts (fl esh body, head,
fi ns, and viscera) were prepared with or without the addition of enzymes,
such as soybean koji ( Aspergilus oryzae ), ang-khak ( Monacus purpureus ) or
viscera in order to produce fi sh sauce. The results indicated that treated
bonitos (whole fi sh and waste) with soybean koji and ang-khak had higher
total sugar content and amylase activities values ranging from 10.8-17.4
mg/l and 5.0-100 U/ml, respectively. On the contrary, total sugar content
of treated bonitos without the addition of enzymes ranged from 3.6 to