RESUMO
Polyhydroxyalkanoates (PHA) are renewable, biodegradable biopolymer intracellularly accumulated by wide array of microorganisms as carbon reserve. This study investigates the influence of various cultural conditions on PHA production by a recently isolated local species under submerged fermentation. Six PHA producing strains were identified by 16S rDNA gene sequencing and strain Priestia flexa OWO1 showed satisfactory PHA productivity. The effects of production parameters were investigated and extraction of PHA was carried out using sodium hypochlorite method and maximum amount was detected after 72h. Maximum PHA production was obtained at incubation period of 48h, pH of 7.0 and temperature of 30oC. Amongst the hydrolysate of agro waste used, brewers spent grain (BSG) gave maximum yield of 3.01g/L while beans bran powder gave the highest PHA yields of 3.9 g/L amongst the organic nitrogen sources tested. Analysis of the crude PHA by Fourier Transform Infrared Spectroscopy (FT-IR) showed the presence of methyl, methylene as well as carbonyl functional groups. PHA production was higher after optimizing the production conditions as compared to basal medium therefore the utilization of these cheap renewable resources as alternative substrates for production of PHA make the process cost effective and sustainable.
RESUMO
Aim: To study the commercial preparation of Kunun zaki in three locations in Port Harcourt namely; Bori-camp, Rumuodomaya and Mgbuogba, to compare the microbiological, physico-chemical, and nutritional qualities of commercial and laboratoryprepared Kunun drinks and to establish the critical control points at various points of the production process. Place and Duration of Study: Sample collection areas were Bori-camp, Rumuodomaya, Mgbuogba, and the Laboratory, between August and December 2012. Sample analysis was done in the Food and Industrial Microbiology Laboratory of University of Port Harcourt. Methodology: At selected stages of preparation of Kunun zaki from Bori-camp, Rumuodomaya, Mgbuogba and the Laboratory, nine samples each were collected into sterile screw-capped 50cl bottles for analysis at the Food and Industrial Microbiology laboratory of University of Port Harcourt. Analyses carried out were to determine the microbial contaminants, proximate and physico-chemical parameters. Samples of fresh Kunun zaki were stored at 5ºC for three days for analysis on effect of storage. Results: The microorganisms associated with freshly prepared Kunun zaki and that stored at refrigeration temperature (5ºC) for three days were Lactobacillus spp., Bacillus spp., Leuconostoc spp., Streptococcus spp., Micrococcus spp., Staphylococcus spp., Pseudomonas spp., Escherichia coli, Enterobacter spp., Penicillium spp., Mucor spp., Aspergillus spp., Rhizopus spp., Candida spp., and Saccharomyces spp. Freshlyprepared Kunun zaki had the highest coliform and staphylococci counts of 8.0x104 and 8.3x103cfu/ml respectively in Bori-camp preparation, while Laboratory-prepared Kunun zaki harboured none of these organisms. Total viable counts of commercially-prepared (Bori-camp, Rumuodomaya, and Mgbuogba) products ranged from 2.50x104 to 1.53x106cfu/ml, while Laboratory-prepared product was 6.0x104cfu/ml. Fungal counts of commercially-prepared Kunun zaki ranged from 2.5x103 to 1.36x105cfu/ml, while Laboratory-prepared Kunun zaki had fungal counts of 5.6x102cfu/ml. Yeasts were the main spoilage organisms which persisted at storage temperature of 5ºC for three days. The protein and carbohydrate contents, as well as calcium, zinc, copper, and manganese decreased after being stored for three days at 5ºC. Conclusion: Therefore Kunun zaki could be safely consumed after storage at 5ºC for three days, if good manufacturing practices like the use of fresh non-moldy grains and spices, cooled boiled water for grain washing and steeping, sterile stainless steel containers, steam-sterilized grinder, and sterile screw-capped bottles for packaging be applied at all the production stages. Educating the producers on the hazards, critical control points (steeping, milling and packaging), and temperature maintenance for Kunun zaki preparation are important.