Search Results (31)

The global biobased plastics market is on an upward trajectory due to the quest for a clean/sustainable environment and the growing concerns over climate change. This study used a meta-analysis approach to investigate the global trend in the research evolution and development of bio-based plastics research from 1990 to 2023. The publication records of 2742 articles were retrieved from the Web of Science data collection using the following key terms: “bioplastic* or biodegradable plastic* or biobased plastic* or biodegradable polyester* or biobased polyester* or biodegradable polyethylene* or biobased polyethylene*”. The analysis showed that scientific productivity generally increased across the spectrum of the survey timelines, with the highest publication of 331 articles recorded in 2023. The articles were published in 863 sources by 10,408 authors, with an annual growth rate of 13.55%. China demonstrated the highest number of publications recorded, with 404 articles within the survey period, followed by the United States, with 303 articles. The international collaboration was recorded at 20.86%, while the average citation per article was 27.99. The swift advancement in biodegradable plastic research, as indicated by relevant metrics, highlights the current research trends and underscores the importance of bio-based plastics in promoting a sustainable environment and a circular economy. Full article

Laccases are multicopper oxidases that exhibit a broad substrate spectrum, making them excellent biocatalysts for clean technological processes. The study isolated novel laccase-producing bacteria from decomposed wood samples and characterized the enzyme for potential industrial and biotechnological applications. The results showed that three bacteria, SP-2, SP-1, and WP-2, out of the eight isolated bacteria, oxidized both guaiacol and α-naphthol in the plate assay and exhibited extracellular laccase activity of 7.0 ± 0.01, 6.67 ± 0.02, and 7.40 ± 0.04 (U/mL), respectively. WP-2 was selected for further study and was identified as Bacillus sp. GLN (accessioned number: MK290989). Strain GLN maximally secreted laccase 48 h post-fermentation, with an enzyme yield of 36.83 ± 2.47 U/mL in optimized conditions. The crude laccase was optimally active at pH 9.0 and 90 °C and showed excellent pH and thermal stability, retaining approximately 65% residual activity at 100 °C for 270 min. GLN laccase demonstrated remarkable stability after treatment with organic solvents and metal ions, retaining more than 50% of its original activity in the presence of 100 mM inhibitors. The data from this study highlight the relevance of Bacillus sp. GLN and its laccase in promoting clean technology. Full article

Dump sites harbour microorganisms with potential for environmentally friendly industrial applications. This study assessed the lipolytic activity of municipal dumpsite-associated bacteria and evaluated the stability of the most potent isolate’s lipolytic enzyme against laundry detergents. It also examined the crude lipase’s ability to remove stains from cotton fabric. Among twelve bacteria isolated, five demonstrated notable halo zones on tributyrin agar plates. The diameters (mm) were MN38 (11 ± 1.4), MN1310 (8.5 ± 0.7), MN28 (6.5 ± 0.71), MN18 (7.0 ± 1.4), and MN310 (8.15 ± 0.21). Quantitative analysis revealed that MN38 exhibited the highest lipase activity (14.76 ± 0.27 U/mL), while MN1310 showed the lowest (6.40 ± 0.85 U/mL). Nucleotide sequence analysis identified the isolates as Raoultella terrigena veli18 (MN38), Stenotrophomonas maltophilia veli96 (MN1310), Viridibacillus sp. veli10 (MN28), Stenotrophomonas sp. veli19 (MN18), and Klebsiella sp. veli70 (MN310). The crude lipase from R. terrigena veli18 maintained 73.33%, 52.67%, 55.0%, and 54.0% of its original activity after 60 min of exposure to Sunlight, Surf, Maq, and Omo, respectively. Adding crude lipase to enzyme-free laundry detergents significantly enhanced their cleaning efficacy, completely removing oil stains from cotton fabric. This performance of R. terrigena veli18 crude lipase highlights its potential as an effective detergent bio-additive. Full article

Though the keratin content of chicken feathers is being explored for many potential uses, the crude lipid content of the biomass significantly hinders the valorization processes. Therefore, this study explored the potential of bacteria isolated from sediment for lipolytic properties. Sediment-associated strains were evaluated for lipolytic activity on tween 80–peptone agar. The best lipolytic bacterium was used to break down the lipid content of chicken feathers. The results showed that out of six bacterial strains with variable lipolytic activity, strain TTs1 showed the largest zone of precipitate around the colony, which is why it was selected and identified as Bacillus sp. TTs1. The maximum lipase production of 1530.5 U/mL by strain TTs1 was achieved at 96 h post-fermentation, with optimal process conditions of initial pH (10), incubation temperature (45 °C), agitation speed (140 rpm), inoculum size (2% v/v) and tween 80 (10% v/v). The total free fatty acid (0.58%) was liberated from chicken feathers at a concentration of 6% (w/v). Crude fat extraction from both untreated and TTs1-pretreated chicken feathers showed fat contents of 2.1 ± 0.42% and 0.92 ± 0.13%, respectively. The findings of this study highlight the biotechnological relevance of strain TTs1 in lipase production and the sustainable delipidation of lipid-rich bioresources. Full article

P. aeruginosa (P. aeruginosa) is a problematic hospital agent that is a global challenge due to the ineffectiveness of some conventional antimicrobial therapies. Multidrug-resistant (MDR) P. aeruginosa has distinct action modes, including beta-lactamase production, porin gene repression, and efflux pump overexpression. This current research work focuses on efflux pumps (MexAB-OprM, MexCD-OprJ, MexXY-OprN) and their regulatory proteins (NfxB, MexR, MexZ, NalC, NalD) in MDR P. aeruginosa isolated from hospital wastewater effluent. The sequence analysis of the main transporter MexB was also performed. Following antibiotic resistance profiling and polymerase chain reaction (PCR) amplification of the efflux pump genes, the association of the efflux pump proteins with antibiotic resistance was investigated and analysed statistically. Fifty-seven (57) multidrug-resistant isolates were obtained from 81 PCR-confirmed P. aeruginosa isolates. Of the MDR P. aeruginosa isolates, the following rates were recorded: MexA (96.5%), MexB (100%), OprM (96.5%), MexC (100%), MexD (74.1%), OprJ (63.7%), MexX (89.6%), and OprN (51.7%). Additionally, the regulatory proteins had the following rates: NfxB (31.6%), NalC (15.8%), NalD (12.2%), MexZ (3.5%), and MexR (3.5%). The efflux pumps and regulatory proteins are strongly associated with antibiotic resistance, implying that P. aeruginosa antibiotic resistance is heavily influenced by these efflux pumps and regulatory genes. The MexB DNA sequences had numerous substitutions and poor alignment with divergent regions, and hence they have a possible role in increased antibiotic resistance. The absence of regulatory genes in most MDR P. aeruginosa isolates in the current research may have permitted transcription of the efflux pump operons, thus also increasing the antibiotic resistance burden. Full article

The nosocomial pathogen Pseudomonas aeruginosa (P. aeruginosa) is characterized by increased prevalence in hospital wastewater and is a public health concern. Untreated wastewater severely challenges human health when discharged into nearby aquatic ecosystems. The antibiogram profiles and resistance genes of P. aeruginosa were evaluated in this study. Wastewater effluents were obtained from a hospital within a six-month sampling period. After the samples were processed and analysed, P. aeruginosa was identified by polymerase chain reaction (PCR) by amplifying OprI and OprL genes. The Kirby–Bauer diffusion technique was employed to check the susceptibility profiles of P. aeruginosa which were further interpreted using CLSI guidelines. A total of 21 resistance genes were investigated among the isolates. The sum of 81 positive P. aeruginosa were isolated in this study. This study’s mean count of Pseudomonas aeruginosa ranged from 2.4 × 105 to 6.5 × 105 CFU/mL. A significant proportion of the isolates were susceptible to imipenem (93%), tobramycin (85%), norfloxacin (85%), aztreonam (70%), ciprofloxacin (51%), meropenem (47%), levofloxacin (43%), and gentamicin (40%). Meanwhile, a low susceptibility was recorded for amikacin and ceftazidime. The overall multiple antibiotics resistance index (MARI) ranged from 0.3 to 0.9, with 75% of the multidrug-resistant isolates. The assessment of β-lactam-resistant genes revealed bla_OXA-1 (3.7%) and bla_SHV (2.4%). The frequency of carbapenem genes was 6.6% for bla_IMP, 6.6% for bla_KPC, 6.6% for bla_oxa-48, 2.2% for bla_NDM-1, 2.2% for bla_GES, and 2.2% for bla_VIM. Of the aminoglycoside genes screened, 8.6% harboured strA, 11.5% harboured aadA, and 1.5% harboured aph(3)-Ia(aphA1). Only one non-β-lactamase gene (qnrA) was detected, with a prevalence of 4.9%. The findings of this study revealed a high prevalence of multidrug-resistant P. aeruginosa and resistance determinants potentially posing environmental health risks. Full article

This study aimed to determine the incidence and virulence factor profiling of Vibrio species from hospital wastewater (HWW) and community wastewater effluents. Wastewater samples from selected sites were collected, processed, and analysed presumptively by the culture dependent methods and molecular techniques. A total of 270 isolates were confirmed as Vibrio genus delineating into V. cholerae (27%), V. parahaemolyticus (9.1%), V. vulnificus (4.1%), and V. fluvialis (3%). The remainder (>50%) may account for other Vibrio species not identified in the study. The four Vibrio species were isolated from secondary hospital wastewater effluent (SHWE), while V. cholerae was the sole specie isolated from Limbede community wastewater effluent (LCWE) and none of the four Vibrio species was recovered from tertiary hospital wastewater effluent (THWE). However, several virulence genes were identified among V. cholerae isolates from SHWE: ToxR (88%), hylA (81%), tcpA (64%), VPI (58%), ctx (44%), and ompU (34%). Virulence genes factors among V. cholerae isolates from LCWE were: ToxR (78%), ctx (67%), tcpA (44%), and hylA (44%). Two different genes (vfh and hupO) were identified in all confirmed V. fluvialis isolates. Among V. vulnificus, vcgA (50%) and vcgB (67%) were detected. In V. parahaemolyticus, tdh (56%) and tlh (100%) were also identified. This finding reveals that the studied aquatic niches pose serious potential health risk with Vibrio species harbouring virulence signatures. The distribution of virulence genes is valuable for ecological site quality, as well as epidemiological marker in the control and management of diseases caused by Vibrio species. Regular monitoring of HWW and communal wastewater effluent would allow relevant establishments to forecast, detect, and mitigate any public health threats in advance. Full article

Klebsiella pneumoniae (K. pneumoniae) is an opportunistic bacteria responsible for many nosocomial and community-acquired infections. The emergence and spread of antibiotic resistances have resulted in widespread epidemics and endemic dissemination of multidrug-resistant pathogens. A total of 145 K. pneumoniae isolates were recovered from hospital wastewater effluents and subjected to antibiogram profiling. Furthermore, the antibiotic resistance determinants were assessed among phenotypic resistant isolates using polymerase chain reaction (PCR). The isolates showed a wide range of antibiotic resistance against 21 selected antibiotics under 11 classes, with the most susceptible shown against imipenem (94.5%) and the most resistant shown against ampicillin (86.2%). The isolates also showed susceptibility to piperacillin/tazobactam (89.0%), ertapenem (87.6%), norfloxacin (86.2%), cefoxitin (86.2%), meropenem (76.6%), doripenem (76.6%), gentamicin (76.6%), chloramphenicol (73.1%), nitrofurantoin (71.7%), ciprofloxacin (79.3%), amikacin (60.7%), and amoxicillin/clavulanic acid (70.4%). Conversely, resistance was also recorded against tetracycline (69%), doxycycline (56.6%), cefuroxime (46.2%), cefotaxime (48.3%), ceftazidime (41.4%). Out of the 32 resistance genes tested, 28 were confirmed, with [tetA (58.8%), tetD (47.89%), tetM (25.2%), tetB (5.9%)], [sul1 (68.4%), sul1I (66.6%)], and [aadA (62.3%), strA (26%), aac(3)-IIa(aacC2)^a (14.4%)] genes having the highest occurrence. Strong significant associations exist among the resistance determinants screened. About 82.7% of the K. pneumoniae isolates were multidrug-resistant (MDR) with a multiple antibiotics resistance index (MARI) range of 0.24 to 1.0. A dual presence of the resistant genes among K. pneumoniae was also observed to occur more frequently than multiple presences. This study reveals a worrisome presence of multidrug-resistant K. pneumoniae isolates and resistance genes in hospital waste effluent, resulting in higher public health risks using untreated surface water for human consumption. As a result, adequate water treatment and monitoring initiatives designed to monitor antimicrobial resistance patterns in the aquatic ecosystem are required. Full article

Keratinases are considerably gaining momentum in green technology because of their endowed robustness and multifaceted application potentials, such as keratinous agro-wastes valorization. Therefore, the production of novel keratinases from relatively nonpathogenic bacteria grown in agro-wastes formulated medium is cost-effective, and also imperative for the sustainability of thriving bioeconomy. In this study, we optimized keratinase production by Bacillus sp. Nnolim-K1 grown in chicken feather formulated medium. The produced keratinase (KerBNK1) was biochemically characterized and also, the keratinase-encoding gene (kerBNK1) was amplified and sequenced. The optimal physicochemical conditions for extracellular keratinase production determined were 0.8% (w/v) xylose, 1.0% (w/v) feather, and 3.0% (v/v) inoculum size, pH 5.0, temperature (25 °C) and agitation speed (150 rpm). The maximum keratinase activity of 1943.43 ± 0.0 U/mL was achieved after 120 h of fermentation. KerBNK1 was optimally active at pH and temperature of 8.0 and 60 °C, respectively; with remarkable pH and thermal stability. KerBNK1 activity was inhibited by ethylenediamine tetra-acetic acid and 1,10-phenanthroline, suggesting a metallo-keratinase. The amplified kerBNK1 showed a band size of 1104 bp and the nucleotide sequence was submitted to the GenBank with accession number MT268133. Bacillus sp. Nnolim-K1 and the keratinase displayed potentials that demand industrial and biotechnological exploitations. Full article

Distribution, investigation, surveillance and control (DISC) of cholera outbreaks in endemic/non-endemic regions has been a concerted approach towards the management of the causal pathogen. Relevant organization, government, health systems and the public have implemented several steps towards controlling the menace, yet pathogen continues to occur with diverse phenotypes/genotypes of high clinical and epidemiological relevance. The study determines antibiotic susceptibility/resistance pattern of Vibrio cholerae isolates retrieved from six domestic water sources between March and August 2018. Serological and molecular typing methods (polymerase chain reaction or PCR) were used to confirm the isolates identity. Antibiotic susceptibility testing was conducted using six commonly employed antibiotics of V. cholerae according to the recommendation of Clinical Laboratory Standard and European Committee for Antimicrobial Susceptibility Testing with other relevant antibiotics of investigative epidemiology and infection control, employing both disc diffusion test and PCR gene detection. Samples presumptive counts ranged between 1.10 to 7.91 log10 CFU/mL. Amongst the 759 presumptive isolates retrieved, sixty-one were confirmed as V. cholerae which were further serogrouped as Non-O1/Non-O139 V. cholerae. Various V. cholerae resistant phenotypes/genoytypes were detected vis: carbapenemase (CR-Vc; 31.1%/5.3%). New Delhi Metallobetalactamase (NDM-1-Vc; 23.0%/42.5%), extended spectrum betalactamase (ESBL-Vc; 42.6%/blaTEM:86,7%), chloramphenicol resistance (62.3%/Flor: 46.2%}, tetracycline resistance (70.5%/46.7%), AmpC resistance (21.0 (34.4%/56.7%)) and various other resistant genotypes/phenotypes. It was observed that more than 50% of the confirmed V. cholerae isolates possess resistance to two or more antibiotic classes/groups with multiple antibiotic resistance index (MARI) ranging from 0.031 to 0.5. This observation provides necessary information and updates for surveillance, planning and implementation of control strategies for cholera. It would also encourage decision making, formulation of policy by the government and cholera control authorities. Full article

Chicken feathers are predominantly composed of keratin; hence, valorizing the wastes becomes an imperative. In view of this, we isolated keratinase-producing bacteria and identified them through the 16S rDNA sequence. The process condition for keratinase activity was optimized, and electron micrography of the degradation timelines was determined. Keratinolytic bacteria were isolated and identified as Bacillus sp. FPF-1, Chryseobacterium sp. FPF-8, Brevibacillus sp. Nnolim-K2, Brevibacillus sp. FPF-12 and Brevibacillus sp. FSS-1; and their respective nucleotide sequences were deposited in GenBank, with the accession numbers MG214993, MG214994, MG214995, MG214996 and MG214999. The degree of feather degradation and keratinase concentration among the isolates ranged from 62.5 ± 2.12 to 86.0 ± 1.41(%) and 214.55 ± 5.14 to 440.01 ± 20.57 (U/mL), respectively. In the same vein, 0.1% (w/v) xylose, 0.5% (w/v) chicken feather, an initial fermentation pH of 5.0, fermentation temperature of 25 °C and an agitation speed of 150 rpm, respectively, served as the optimal physicochemical conditions for keratinase activity by Bacillus sp. FPF-1. The time course showed that Bacillus sp. FPF-1 yielded a keratinase concentration of 1698.18 ± 53.99(U/mL) at 120 h. The electron microscopic imaging showed completely structural dismemberment of intact chicken feather. Bacillus sp. FPF-1 holds great potential in the valorization of recalcitrant keratinous biomass from the agro sector into useful products. Full article

Natural water sources are very often contaminated by municipal wastewater discharges which contain either of xenobiotic pollutants and their sometimes more toxic degradation products, or both, which frustrates the universal millenium development goal of provision of the relatively scarce pristine freshwater to water-scarce and -stressed communities, in order to augment their socioeconomic well-being. Seeing that both regulatory measures, as regards the discharge limits of wastewater, and the query for efficient treatment methods remain unanswered, partially, the prospects of enzymatic treatment of wastewater is advisable. Therefore, a reconsideration was assigned to the possible capacity of oxidative enzymes and the respective challenges encountered during their applications in wastewater treatment, and ultimately, the prospects of laccase, a polyphenol oxidase that oxidizes aromatic and inorganic substrates with electron-donating groups in treatment aromatic contaminants of wastewater, in real wastewater situations, since it is assumed to be a vehicle for a greener community. Furthermore, the importance of laccase-driven catalysis toward maintaining mass-energy balance, hence minimizing environmental waste, was comprehensibly elucidated, as well the strategic positioning of laccase in a model wastewater treatment facility for effective treatment of wastewater contaminants. Full article

Bioflocculants mediate the removal of suspended particles from solution and the efficiency of flocculation is dependent on the characteristics of the flocculant. Apart from the merits of biodegradability and harmlessness, bioflocculants could be viable as industrially relevant flocculants as they are a renewable resource. Additionally, the shortcomings associated with the conventionally used flocculants such as aluminium salts and acrylamide polymers, which include dementia and cancer, highlight more the need to use bioflocculants as an alternative. Consequently, in this study a marine sediment bacterial isolate was screened for bioflocculant production. Basic local alignment search tools (BLAST) analysis of 16S ribosomal deoxyribonucleic acid (rDNA) sequence of the bacterial isolate showed 98% similarity to Bacillus thuringiensis MR-R1. The bacteria produced bioflocculant optimally with inoculum size (4% v/v) (85%), glucose (85.65%) and mixed nitrogen source (urea, ammonium chloride and yeast extract) (75.9%) and the divalent cation (Ca²⁺) (62.3%). Under optimal conditions, a maximum flocculating activity of over 85% was attained after 60 h of cultivation. The purified polysaccharide-bioflocculant flocculated optimally at alkaline pH 12 (81%), in the presence of Mn²⁺ (73%) and Ca²⁺ (72.8%). The high flocculation activity shown indicates that the bioflocculant may contend favourably as an alternative to the conventionally used flocculants in water treatment. Full article

This paper reports on the optimization of culture conditions for cellulase and xylanase production by bacterial isolate from lignocellulosic biomass. The bacterial isolate was screened for cellulase and xylanase production on carboxyl methyl cellulose (CMC) and birch wood xylan as substrates, respectively. One bacterial isolate showing the highest halo zone diameter (isolate PLY1) was selected for detailed studies. The analysis of the 16S ribosomal ribonucleic acid (rRNA) gene nucleotide sequence of PLY1 revealed it to have 98% similarity to Micrococcus luteus strain Fse9 and the sequence was deposited in the GenBank as Micrococcus luteus strain SAMRC-UFH3 with accession number KU171371. Cellulase production was achieved in the presence of CMC (1% w/v) under an incubation temperature of 25 °C (198 U/mL), pH 5 (173 U/mL), agitation speed 50 rpm (173 U/mL) and incubation period of 96 h (102 U/mL). Xylanase was produced maximally when birch wood xylan (1% w/v) was used as the substrate at 25 °C (1007 U/mL), pH 10 (2487 U/mL), 200 rpm (1814 U/mL), and under an incubation period of 84 h (1296 U/mL). Our findings showed that Micrococcus sp. SAMRC-UFH3 appears to be a potentially important candidate for lignocellulosic waste degradation and other relevant industrial applications. Full article

Cellulase and xylanase are in high demand for application in several industrial processes, consequently necessitating the bioprospecting and manipulation of microbes for novel and greater enzyme productivity. This study reports on the optimal conditions for cellulase and xylanase production by a marine bacterial isolate from Nahoon beach sediment, via the classical process of one variable per time. Furthermore, the inducing effect of mono- and polysaccharides on enzyme production was investigated. The 16S rDNA gene sequence analysis clearly assigned the isolate to the genus Streptomyces, and was deposited at the GenBank under the accession number KU171373. Cellulase and xylanase production was optimal at the following conditions: pH 6 and 8, incubation temperature of 40 and 35 °C, and agitation speed of 100 and 150 rpm, respectively. Under optimum conditions, 0.26 U/mL and 18.54 U/mL activities were attained at 60 and 48 h with specific productivity of 205 and 7417 U/g for cellulase and xylanase, respectively. Xylanase production was induced by the entire mono- and polysaccharides tested, while cellulase production was induced by some. The results from this study signify the resourcefulness of the Streptomyces strain for production of cellulase and xylanase of industrial importance. Full article