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Cellulolytic index of isolated cellulolytic bacteria
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Insects of the taxonomic order Coleoptera are recognized for considerable cellulolytic activity in their digestive tract. However, the cellulolytic activity of the gut microbiome of the African palm weevil (Rhynchoporus phoenicis), has not been reported. Thus, this study aimed at isolating cellulose degrading bacteria from the gut of the insect's l...
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... It is widely harvested, marketed and consumed all over Bayelsa State, the entire Southern Nigeria and across the Niger Delta at large; and eaten either as raw (or fresh), boiled, fried, smoked or used in stew or soup (Okaraonye and Ikewuchi, 2008). APW grubs are cherished delicacy amongst all rural and urban dwellers and populace (Omotosho and Adedire, 2007); and are commonly called diverse descriptive names within the region viz: "Bayelsa suya" (Bayelsa and Rivers States), "edible worms or maggots" (Sapele, Delta State), "diet" (Warri, Delta State), "chaffer" (Rivers State) etc., (Lale, 1996;Immanuel et al., 2022). ...
The African palm weevil, Rhynchophorus phoenicis F. (Coleoptera: Curculionidae) constitutes a significant component in diets of the Niger Delta of Nigeria. This study aimed to determine the proximate composition and microbiological quality of processed grubs (steamed, dried, fried and fresh which served as control) purchased from food vendors in Toru-Orua community. Proximate composition determinations followed official methods recommended by the Association of Official and Analytical Chemicals (AOAC), while microbial load was determined by total plate count. Steamed grubs had the highest moisture content of 15% while fresh had the least moisture content of 9.3%. Steamed grubs had the highest ash content of 11.47% while fresh had the least ash content of 4.73%. Fresh grubs had the highest crude protein of 41.75% while fresh had the least crude protein of 30.13%. Steamed grubs had the highest crude fibre content of 18.07% while fresh had the least crude fibre of 13.7%. Steamed and fried grubs had the highest crude fat content of 10.93% while fresh had the least crude fat content of 2.8%. Steamed grubs had the highest moisture content of 28.35% while dried grubs had the least moisture content of 20.66%. The total heterotrophic bacteria count ranged from 8.5 x 10 2 CFU/g-3.7 x 10 6 CFU/g. Fungal count ranged from 2.2 x 10 2-3.4 x 10 3 CFU/g. The microbial investigations showed Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus were the common microorganisms on the grubs. Frequent microbiological quality checks on such ready-to-eat foods, along with public enlightenment campaigns for food vendors is recommended, to guarantee food safety for consumers during processing/handling, storage and consumption.
... Among these products is polyhydroxyalkanoate (PHA), a compound with properties which is currently being utilized for the production of biodegradable plastic. The larvae of the African palm weevil (Rhynchophoros phoenicis) are voracious and can feed on hard palm fibre (Immanuel et al., 2022). In the present study, we exploited the degradation of PS by bacteria isolated from the gut of R. phoenicis larvae and investigated the possibility of coupling its degradation with PHA production. ...
... Among them, only two isolates were able to grow on a minimal medium containing PS as the only carbon source. The total number of isolates is much lower than the previously reported number of isolates by Immanuel et al. (2022), after feeding with palm pith. This aligns with a report indicating that microbial miscellany is positively correlated to the diet of insects (Priya et al., 2012;Krams et al., 2017). ...
The larvae of insects of the order Coleoptera have been reported to biodegrade plastics aided by their chewing mouthparts and the activities of their gut biota. However, there is no report of this ability by the African palm weevil (Rhynchophorus phoenicis). This study aims to the ability of R. phoenicis larvae to biodegrade polystyrene (PS). A total of 100 R. phoenicis larvae were fed for 21 days with PS foam, and afterwards, the gut contents of survivors were investigated for possible PS-degrading bacteria. Bacterial isolates were screened for PS biodegradation in an Erlenmeyer flask with PS film as the sole carbon source, in a mineral salt medium (MSM) at a temperature of 30 o C and a pH of 7, for a period of 28 days. The isolates were used for biodegradation assay under the same conditions, for 60 days. The weight of PS films was determined before and after the biodegradation assay. Chemical changes in the films were confirmed by Fourier Transform Infrared (FTIR) spectroscopy. Two bacterial isolates were recovered from the gut of the only surviving R. phoenicis larvae fed with 100% PS. The isolates were identified based on their 16S rRNA sequences as Lysinibacillus macriodes and Pantoea dispersa with accession numbers OQ652017 and OQ652023 respectively. The isolates caused an 8.8% reduction in the weight of PS film and FTIR spectroscopy results confirmed the formation of groups suggestive of degradation products with the carbonyl group showing up as absorption peaks in the range of 1640-1760 cm-1 and the hydroxylic group at 3000-3700 cm-1. The isolates were able to produce polyhydroxyalkanoate (PHA) equivalent to 1.4g/L, under PS degradation conditions. Therefore, coupling the biodegradation of PS with PHA production could be useful for the valorization of PS waste.
The indispensability of plastics in everyday life has made the search for environmentally sustainable alternatives to these nonbiodegradable polymers more earnest. Polyhydroxyalkanoates (PHAs) are a class of biodegradable, biocompatible plastics comprising of polyesters of R-hydroxyalkanoic acids. They are accumulated intracellularly as polymeric granules upon cultivating several gram-positive and gram-negative bacteria in nutrient-limiting conditions. Hence, the objective of this paper is to investigate the production of polyhydroxyalkanoates by bacteria isolated from the gut of the larvae of African Palm Weevil (Rhynchophorus phoenicis) using agricultural-waste substrates. Two bacteria isolated from the gut of polystyrene-fed R. phoenicis larvae were utilized for the production of PHA using brewery waste, bean hull, cassava peel and palm pith, as substrates. The bacteria were identified as Lysinibacillus macriodes and Pantoea dispersa. Isolate P. dispersa accumulated PHAs ranging from 0.89-1.44 g/L from agricultural waste and 4.24 g/L from glucose, equivalent to 30.8%-46.7% and 71.9% yields respectively. L. macrolides, accumulated PHAs ranging from 1.11-1.50 g/L from agricultural waste and 3.89 g/L from glucose equivalent to 40.4%-48.1% and 69.2% yields respectively. The isolates can be desirable candidates for PHAs production under optimized conditions.
The ceaseless quest for economical cellulase, an enzyme that hydrolyzes cellulose, has led to exploring diverse environments, such as insect guts. In this study, we report the optimization of cellulase production and isolation, purification, and characterization of cellulose-degrading enzymes from Aspergillus awamori AFE1 . Aspergillus awamori AFE1 was screened for its cellulase-degrading ability, and molecular and phylogenetic analyses of the isolate were performed. Two activity peaks were observed during ion exchange chromatography. A final purification fold of 0.86 and 1.86 with a recovery of 0.18% and 0.44% were achieved for cellulase A and B, respectively; molecular weight of 48.5 KDa and 36.5 KDa for A and B, respectively. The optimum pH of 5.0 was observed for both purified cellulases, and both were stable at an acidic pH of 4.0. An optimum temperature of 60 o C for CA and dual optimum temperatures of 60 and 70 o C were obtained for CB, while both were stable at 30 o C with 63 and 61% residual activity after 2 h, respectively. Fe ²⁺ stimulated both cellulase activity, whereas Zn ²⁺ , Cu ²⁺ , Mn ²⁺ , K +, and Na ⁺ inhibited cellulase activity. Similarly, urea, ascorbic acid, and EDTA inhibited the enzyme. The enzymes were stable in the presence of some organic solvents. The K m and V max values were found to be 3.86 mM and 0.3159 mg/ml/min, 4.12 mM, and 0.223 mg/ml/min for the enzyme. The remarkable and unique physicochemical properties of cellulases from Aspergillus awamori AFE1 could be exploited for industrial and biotechnological applications.
