By: Mr. Matthews Mokoba and Prof Amare Gessesse(Department of Biological Sciences and Biotechnology,Faculty of Science, BIUST
In recent years there has been a sharp increase in poultry meat consumption worldwide. With the increasing world population, this trend is expected to and that could lead to an increase in the slaughtering of millions of chickens every year. An increase in poultry meat consumption inevitably leads to an increase in the release of waste and its accumulation around processing sites.
Feather is one of the major waste types released by the poultry industry. Between 5 to 7% of the live weight of chicken is accounted for by feather. As a result, globally millions of tons of feather waste are generated by the poultry industry.Feather is composed of over 90% protein which makes it an ideal animal feed or as a source of valuable amino acids for other applications. However, a feather is a highly crystalline and hard structure highly resistant to digestion by enzymes that exist in the animal gut.
As a result, the current practice of dealing with feather waste is disposal by burying underground or through incineration. These practices, in addition to causing disposal and handling costs to poultry processing companies, raise serious environmental concerns. Therefore, the development of efficient biotechnological methods for the hydrolysis of a feather could allow its utilization for different applications while also helping avoid environmental pollution. In nature, a feather is abundant at sites where there are flocks of birds.
The Makgadikgadi salt pan is one such area where a flock of flamingos appear during the rainy season that releases large quantities of the feather. However, no accumulation of flamingo feathers is observed after a few weeks or months suggesting degradation by soil microorganisms. Interestingly the soil in the salt pan is alkaline and saline indicating that any microorganism surviving in these environments must optimally grow and produce enzymes that are active and stable under alkaline conditions.Feather being a protein, the enzymes involved in its degradation are the class known as proteases.
At present, alkaline proteases account for over a quarter of the global industrial enzyme market. They find important applications in the detergent, food, feed, and leather tanning industries. All the known alkaline proteases are produced by microorganisms, some of them alkaliphilic.
Despite their widespread use as processing aids in different industrial processes, industrial enzymes remain very expensive because of the high production cost. Some estimates show that up to 40% of the production cost is accounted for by the growth substrate. Based on our observation on the degradation of the flamingo feather at the Makgadikgadi salt pan and the alkaline nature of the soil, we thought that we can get efficient feather degrading microorganisms from these habitats.
Therefore, one of the objectives of our study was to isolate an alkaline loving (alkaliphilic) bacteria that grown using a cheap substrate, feather, and produce alkaline enzymes.
Our second objective was to evaluate the potential application of the enzyme for different industrial applications.A protease producing alkaliphilic bacteria, identified as Bacillus pseudofirmus, was isolated from soil collected at the Makgadikgadi salt pan. The organism grew using chicken feathers as the sole nitrogen source. Thus, the organism solubilizes the insoluble feather in a short period and release an alkaline protease, soluble proteins, peptides, and amino acids.
Evaluation of the enzyme under different application conditions showed that it can be efficiently used as a detergent additive showing excellent performance under standard washing conditions.
The same protease was also tested for the hydrolysis of plant proteins to be used for food and non-food applications. For example, in one study the enzyme was used to hydrolyze baobab and soybean proteins to produce peptone as a component of microbiological media.
The resulting peptone supported microbial growth equal or better than commercial peptone indicating the possibility of producing such products using this enzyme. Peptones are one of the expensive components of the microbiological media used in research and clinical laboratories. The enzyme has also been shown to have an interesting potential for the dehairing of animal skin in the leather tanning industry.
Since the organism grows and produces the enzyme using a cheap substrate, chicken feather, first we expect the cost of production of the enzyme could be greatly reduced and this, in turn, could allow wider applications of such enzyme in different industrial sectors.
Second, utilisation of the feather as a microbial growth substrate (or enzymatic hydrolysis) reduces or avoid the disposal problem poultry processing factories currently face. Third, the hydrolysis products of a feather can potentially be used as animal feed supplements or as a source of valuable amino acids.Currently, further study is underway in our laboratory to scale up the process and evaluate other potential applications.