Microbiological quality of fresh catfish raised in ponds fertilized with raw sterilized poultry manures

A total of 2,800 catfish (Clarias gariepinus) were stocked in fourteen (14) 5 by 4 m2 earthen ponds in NJFFR Integrated Farm, New Bussa, Niger State. Raw and sterilized poultry manure of 0.13 to 0.52 kg/m3 concentrations were used to fertilize the ponds with the unfertilized ponds serving as control. The following bacteria were isolated from the poultry manure; Escherichia coli, Aeromonas hydrophila, Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus. The microbial loads of samples increased with increase in concentration of manure. The fish samples from the 0.13 and 0.26kg/m3 sterilized manure fertilized ponds had no count in their fish flesh unlike others. However, the fish from the control ponds had the least with 0.68 log10 CFU/g while that of fish harvested from 0.52 kg/m3 raw manure fertilized ponds had the highest with 2.24 log10 CFU/g. Pathogenic enteric organisms like S. typhi, S. dysenteriae and A. hydrophila were not present in the fish flesh of the fish from the sterilized manure and control samples. The study revealed that fish samples from sterilized manures were better in terms of microbial safety for fish productions; hence sterilized manure is recommended for use in fish production to ensure the microbial safety of the fish, handlers and that of the consumers

Effects of evaporative cooling storage on microbiological and nutritional quality of Telfairia occidentalis Hook. f. and Amaranthus hybridus L.

This study investigated the effect of two evaporative cooling systems (ECS) on the preservation of nutritional qualities and shelf-life of Amaranthus hybridus and Telfairia occidentalis. Samples were kept in block-in-block (BB) and metal-in-block (MB) ECS structures for up to 7 days and monitored for physicochemical, nutritional, and microbiological changes. The temperature in the ECS structures ranged from 25.8 to 28.5 °C for MB and 25.3 to 28.0 °C for BB with the highest relative humidity of more than 71.2% and 70.0%, respectively. The storage conditions for the control samples were 30.9 °C ± 1.0 °C and relative humidity (RH) of 49.3%. MB and BB extended the shelf-life of the Amaranthus hybridus for up to 4 days and Telfairia occidentalis for 7 days, while the control samples deteriorated completely by day 3. Weight loss and mineral contents were significantly higher in the control samples. The pH of all samples dropped during storage. MB-preserved samples had higher amounts of moisture, vitamin C, and carbohydrate although a general decline in these nutrients was observed throughout the storage period. The loss of minerals such as potassium, calcium, magnesium, iron, phosphorus, and sodium was observed in the samples stored under the ECS structures. Heterotrophic bacteria, coliforms, and fungal counts declined throughout the storage period, but the control samples had the highest counts, while MB had the least. MB and BB equally extended the shelf-life of the vegetables, but MB preserved the physicochemical and nutritional attributes of the samples better with lower susceptibility to microbial colonization and spoilage. The study concluded that ECS can be used as a low technology agricultural tool to provide short term preservation of vegetables, ultimately contributing to a reduction in postharvest losses

Utilization of Pachysolen tannophilus and Pichia kudriavzevii for the production of xylitol on undetoxified corn cob hydrolysates

Received: February 19th, 2022 ; Accepted: April 24th, 2022 ; Published: April 29th, 2022 ; Correspondence: [email protected] is a natural polyol with broad applications in the food and pharmaceutical industries. However, its large-scale production through chemical means is still an expensive and not environmentally friendly process. Therefore, great attention has been paid to low-cost and renewable substrates like corn cobs (CC), which can be utilized to improve the economic outlook of xylitol production. In this study, CC were used as a feedstock for xylitol production, with the help of yeasts and filamentous fungi. The results obtained in this study showed that the amount of xylitol produced from CC hydrolysate was similar to the amount of xylitol obtained on xylose substrate. Overall, yeast produced higher amounts of xylitol than filamentous fungi. Pachysolen tannophilus had the highest xylitol production at pH 5.0, 72 h fermentation time, substrate concentration 15%, and inoculum size 1.5×108 cfu mL-1 , while Pichia kudriavzevii performed better at pH 5.0, with a 72 h fermentation time, substrate concentration of 20%, and inoculum size of 2.5×108 cfu mL-1 . When comparing the combined optimal parameters with and without supplementation, supplementation with 1.5% methanol, has increased the xylitol production of P. tannophilus and P. kudriavzevii by 31% and 18.6%, respectively. These findings demonstrate the robustness of these yeast strains for sustainable and cost-effective xylitol production from CC waste

Phosphate solubilization potential of indigenous rhizosphere fungi and their biofertilizer formulations

Received: September 28th, 2021 ; Accepted: December 13th, 2021 ; Published: December 16th, 2021 ; Correspondence: [email protected] harmful effects of chemical fertilizers on soil, plants, and eco-systems have stimulated the growth of the global biofertilizer market. However, biofertilizer use remains limited in developing countries due to inadequate research and poor technology. The use of readily available materials for biofertilizer production can be a good starting point. This study aimed to investigate phosphate-solubilizing potentials of soil fungi and the shelf-life of their biofertilizer formulations using sawdust and charcoal as carriers. Soil samples from the rhizosphere were cultured on Pikovskaya (PVK) agar, and the best phosphate solubilizers (Aspergillus niger, Aspergillus fumigatus and A. flavus) were screened for their phosphatesolubilization potentials on solid medium. Results obtained showed that A. niger had the highest solubilization index of 1.72, followed by A. fumigatus, and A. flavus with a solubilization index of 1.01 and 0.95, respectively. Optimization studies showed that after 5 days of incubation, A. niger, A. flavus and A. fumigatus solubilized 149, 112 and 126 mg L-1 of phosphate, respectively. These values increased to 549 mg L-1 on day 11 for A. niger, 379 mg L-1 on day 9 for A. flavus and 430 mg L-1 on day 9 for A. fumigatus. Furthermore, A. fumigatus and A. flavus proved to be better inoculants than A. niger as they maintained higher CFU g-1 counts throughout the experiment. Also, sawdust supported higher counts of the three inoculants than charcoal and was thus the best carrier. The findings demonstrated that these aspergilli can be harnessed for improving soil fertility and plant development