Aqueous extract of bay leaf (Laurus nobilis) ameliorates testicular toxicity induced by aluminum chloride in rats

Background and Aim

Human exposure to aluminum is inevitable, and one of the most adverse health effects of aluminum is a decrease in male fertility rates. Therefore, this study investigated the ameliorative effects of an aqueous extract from Laurus nobilis-bay leaf (BL) on aluminum chloride (AlCl₃)-induced testicular toxicity in rats.

Materials and Methods

Twenty-four Wistar rats were divided into four groups (n = 6, each group): The control (group 1) received normal saline; Group 2 animals were intraperitoneally administered with 30 mg/kg body weight (BW) AlCl₃; and Groups 3 and 4 were co-administered AlCl₃ with 125 or 250 mg/kg BW of BL extract, respectively, for 21 days. Testes, epididymis, and blood samples were collected. Testicular plasma enzyme activity was measured using a spectrophotometric assay, while concentrations of inflammatory biomarkers were determined using enzyme-linked immunosorbent assay kits.

Results

There was a significant increase (p < 0.05) in testicular enzyme activity in the group treated with AlCl₃. However, there was no significant (p > 0.05) difference in testicular enzyme activity in groups co-administered AlCl₃ and BL extract as compared with that in control. There was a significant (p < 0.05) increase in testicular nitrite concentration in the AlCl₃-treated group, whereas the administration of BL extract significantly (p < 0.05) decreased nitrite concentration in Groups 3 and 4. Furthermore, the administration of BL extracts increased sperm count and improved the morphology of the testes in AlCl₃-treated rats. Flavonoids, phenolic compounds, alkaloids, tannin, glycosides, saponin, anthraquinones, and steroids were identified in BL extract, with alkaloids and glycosides being the most abundant.

Conclusion

Aqueous extract from BL ameliorated the toxic effect of AlCl₃ and exhibited anti-inflammatory properties by inhibiting nitrite production while improving sperm count and morphology in AlCl₃-treated rats. The bioactivity of the extract may be attributed to the presence of a wide range of phytochemicals. Therefore, BL aqueous extract could be a promising source of novel compounds with male fertility-promoting and anti-inflammatory properties.

Aptitude of endophytic microbes for production of novel biocontrol agents and industrial enzymes towards agro-industrial sustainability

Background

Endophytes have continued to receive increased attention worldwide, probably, due to the enormous biotechnological potentials spanning through various industrial sectors. This paper outlines the biotechnological potentials of endophytes in biocontrol and industrial enzyme production, and the possible contribution towards achieving agro-industrial sustainability using published articles on endophytes in both Web of Science and Scopus (1990–2020).

Main body of the abstract

This review discusses the potential of endophytes to produce novel secondary metabolites with effective biocontrol activity against insect pests and plant pathogens. More so, the aptitude of endophytes for production of a wide range of enzymes with potential applications in agriculture, energy and health is discussed in this review. Furthermore, this review highlights the emerging potentials of endophytes in the production of exopolysaccharide and fatty acids. This paper also advocates the need for bioprospecting endophytes for novel biocontrol agents against termites, which are known for causing significant damage to forest and stored products.

Short conclusion

Exploration of endophytes for biocontrol and production of biomolecules of industrial significance could contribute significantly towards agricultural and industrial sustainability.

Agroresidues enhanced peroxidase activity expression by Bacillus sp. MABINYA-1 under submerged fermentation

Agroresidues have continued to gain preference over conventional carbon sources for microbial enzyme production due to the low price and abundance in the environment. Therefore, this study aimed at improving peroxidase yield by Bacillus sp. MABINYA-1 (BMAB-1) using agroresidues under submerged fermentation. The culture parameters that support maximum peroxidase yield by BMAB-1 was initially determined and the results showed that peroxidase activity expression was optimum at pH 5, 30 °C and 150 rpm while veratryl alcohol and ammonium sulphate served as the best peroxidase-inducer and inorganic nitrogen source, respectively. BMAB-1 exhibited maximum peroxidase expression (17.50 ± 0.10 U/mg) at 72 h using kraft lignin liquid medium (KLLM) under the optimized culture conditions. Upon utilization of selected agroresidues (sawdust, wheat straw and maize stover) as sole carbon sources by BMAB-1 in the fermentation process, peroxidase activity was significantly enhanced when compared with glucose (14.91 ± 0.31 U/mg) and kraft lignin (17.50 ± 0.10 U/mg). Sawdust produced the highest peroxidase yield (47.14 ± 0.41 U/mg), followed by maize stover (37.09 ± 0.00 U/mg) while wheat straw yielded the lowest peroxidase specific activity (21.65 ± 0.35 U/mg). This indicates that utilization of sawdust by BMAB-1 resulted in 3.2- and 2.7-fold increase in peroxidase activity expression as compared to glucose and kraft lignin, respectively. The aptitude of BMAB-1 to utilize agroresidues would reduce the cost of peroxidase production by the bacteria since the substrates are cheaper than the conventional carbon sources and are, as well, more readily available.

Emerging biotechnological potentials of DyP-type peroxidases in remediation of lignin wastes and phenolic pollutants: a global assessment (2007-2019)

Dye decolourizing peroxidase (DyP) is an emerging biocatalyst with enormous bioremediation and biotechnological potentials. This study examined the global trend of research related to DyP through a bibliometric analysis. The search term 'dye decolourizing peroxidase' or 'DyP-type peroxidase' was used to retrieve published articles between 2007 and 2019 from the Web of Science (WoS) and Scopus databases. A total of 62 articles were published within the period, with an annual growth rate of 17·6%. The highest research output was observed in 2015, which accounted for about 13% of the total output in 12 years. Germany published the highest number of articles (n = 10, 16·1%) with a total citation of 478. However, the lowest number of published articles among the top 10 countries was observed in India and Korea (n = 2, 3·2%). Research collaboration was low (collaboration index = 4·08). In addition to dye decolourizing peroxidase(s) and DyP-type peroxidase(s) (n = 33, 53·23%), the top authors keywords and research focus included lignin and lignin degradation (n = 10, 16·1 %). More so, peroxidase (n = 59, 95·2%), amino acid sequence (n = 27, 46·8%), lignin (n = 24, 38·7%) and metabolism (n = 23, 37·1%) were highly represented in keywords-plus. The most common conceptual framework from this study include characterization, lignin degradation and environmental proteomics. Apart from the inherent efficient dye-decolourizing properties, this study showed that DyP has emerging biotechnological potentials in lignin degradation and remediation of phenolic environmental pollutants, which at the moment are under explored globally.

Pleurotus ostreatus and Lentinus subnudus supplemented diets restore altered acetylcholinesterase and butyrylcholinesterase activities and improve antioxidant status in transgenic Drosophila melanogaster model

Pleurotus ostreatus (P. ostreatus) and Lentinus subnudus (L. subnudus) have been used by the locals for the management of Alzheimer's disease (AD) but with scant scientific sources. The aim of this study is to assess the neuroprotective properties of P. ostreatus and L. subnudus using transgenic Drosophila melanogaster flies (TDMF). The activity of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), as well as the antioxidant status of TDMF raised on a diet supplemented with P. ostreatus and L. subnudus were determined. The flies were raised on a diet devoid of supplements or supplemented with P. ostreatus or L. subnudus (1% and 5% inclusion) for 7 days. Afterward, AChE and BChE activities, as well as catalase and total thiol level, were determined. The reactive oxygen species (ROS) and malondialdehyde (MDA) levels were also determined in the flies raised on a diet devoid of supplement and on supplemented diets. Meanwhile, flies raised on P. ostreatus- and L. subnudus-supplemented diets exhibited a significant reduction in the activity of AChE and BChE in comparison with the controls. Also, supplemented diets significantly (p < 0.05) enhance catalase activity and improve total thiol level, while ROS and MDA levels were observed to be reduced in all the flies raised on the supplemented diets in comparison with the controls. In summary, reduction in the activity of AChE and BChE, as well as improved antioxidant status in TDMF, could be some of the mechanisms through which P. ostreatus and L. subnudus exhibit anti-AD properties. Nevertheless, L. subnudus exhibits a better neuroprotective effect than P. ostreatus.

Studies on peroxidase production and detection of Sporotrichum thermophile-like catalase-peroxidase gene in a B acillus species isolated from Hogsback forest reserve, South Africa

This study sought to determine the process conditions for optimum peroxidase production by a Bacillus species (Bacillus sp. FALADE-1-KX640922) isolated from Hogsback forest reserve in South Africa and characterize the peroxidase gene in the bacteria. We optimized peroxidase production by manipulating the environmental and nutritional parameters under submerged fermentation. Subsequently, the gene encoding heme-peroxidase was determined through nested polymerase chain reaction and Sanger DNA sequencing. The studied bacteria had maximum peroxidase production at pH 8, 30 °C and 150 rpm. The addition of guaiacol to lignin fermentation medium enhanced peroxidase production by over 100 % in the studied bacteria. However, the other lignin monomers (veratryl alcohol, vanillin, vanillic acid and ferulic acid) repressed the enzyme activity. Modification of the fermentation medium with ammonium sulphate gave the maximum peroxidase yield (8.87 U mL⁻¹). Under the predetermined culture conditions, Bacillus sp. FALADE-1 expressed maximum specific peroxidase activity at 48 h (8.32 U mg⁻¹). Interestingly, a search of the sequenced gene in PeroxiBase showed 100% similarity to Sporotrichum thermophile catalase-peroxidase gene (katG), as well, the deduced protein sequence clustered with bacterial catalase-peroxidases and had a molecular weight of about 11.45 kDa with 7.01 as the estimated isoelectric point. Subsequently, the nucleotide sequence was deposited in the National Center for Biotechnology Information (NCBI) repository with the accession number MF407314. In conclusion, Bacillus sp. FALADE-1 is a promising candidate for improved peroxidase production.

Ligninolytic enzymes: Versatile biocatalysts for the elimination of endocrine-disrupting chemicals in wastewater

Direct municipal wastewater effluent discharge from treatment plants has been identified as the major source of endocrine‐disrupting chemicals (EDC) in freshwaters. Consequently, efficient elimination of EDC in wastewater is significant to good water quality. However, conventional wastewater treatment approaches have been deficient in the complete removal of these contaminants. Hence, the exploration of new and more efficient methods for elimination of EDC in wastewater is imperative. Enzymatic treatment approach has been suggested as a suitable option. Nonetheless, ligninolytic enzymes seem to be the most promising group of enzymes for EDC elimination, perhaps, owing to their unique catalytic properties and characteristic high redox potentials for oxidation of a wide spectrum of organic compounds. Therefore, this paper discusses the potential of some ligninolytic enzymes (laccase, manganese peroxidase, and versatile peroxidase) in the elimination of EDC in wastewater and proposes a new scheme of wastewater treatment process for EDC removal.

Agrowastes utilization by Raoultella ornithinolytica for optimal extracellular peroxidase activity

The industrial applications and prospects of microbial peroxidase are on the upwards trend, thus necessitating the search for sources with high turnaround time. Actinobacterial species have been a major source of peroxidase for the obvious reasons of having robust metabolite expression capabilities. However, other bacteria species have been underexplored for peroxidase production, hence the motivation for the investigation into the peroxidase production potential of Raoultella ornithinolytica OKOH-1 (KX640917). The bacteria expressed optimum specific peroxidase activity of 16.48 ± 0.89 U mg^-1 , which is higher than those previously reported. The optimal fermentation conditions were pH 5 (3.44 ± 0.64 U mL^-1 ), incubation temperature of 35 °C (5.25 ± 0.00 U mL^-1 ), and agitation speed of 150 rpm (9.45 ± 2.57 U mL^-1 ), with guaiacol and ammonium chloride as the best inducer and nitrogen supplement, respectively. On valorization of agrowastes as a sole carbon source for the secretion of peroxidase, sawdust gave the best peroxidase yield (15.21 ± 2.48 U mg^-1 ) under solid-state fermentation. Also, a nonperoxide-dependent enzyme activity, which suggests probable laccase activity, was observed. The ability of the bacteria to utilize agrowastes is highly economical and as well a suitable waste management strategy. Consequently, R. ornithinolytica OKOH-1 is a promising industrial strain with dexterity for enhanced peroxidase production.

Peroxidase production and ligninolytic potentials of fresh water bacteria Raoultella ornithinolytica and Ensifer adhaerens

Interest in novel ligninolytic bacteria has remained topical due to, in part, the maneuverability of the bacterial genome. Conversely, the fungal genome lacks the dexterity for similar maneuverability thus, posing challenges in the fungal enzyme yield optimization process. Some impact of this situation includes the inability to commercialize the bio-catalytic process of lignin degradation by fungi. Consequently, this study assessed some fresh water bacteria isolates for ligninolytic and peroxidase properties through the utilization and degradation of model lignin compounds (guaiacol and veratryl alcohol) and the decolourization of selected ligninolytic indicator dyes; Azure B (AZB), Remazol Brilliant Blue R (RBBR) and Congo Red (CR). Bacterial strains with appreciable ligninolytic and peroxidase production potentials were identified through 16S rDNA sequence analysis and the nucleotide sequences deposited in the GenBank. About 5 isolates were positive for the degradation of both guaiacol (GA) and veratryl alcohol (VA) thus, accounting for about 17% of the test isolates. Similarly, AZB, RBBR and CR were respectively decolorized by 3, 2 and 5 bacterial strains thus, accounting for 10%, 7% and 17% of the test isolates. Two of the test bacterial strains were able to decolourize AZB, RBBR and CR respectively and these bacterial strains were identified as Raoultella ornithinolytica OKOH-1 and Ensifer adhaerens NWODO-2 with respective accession numbers as KX640917 and KX640918. Upon quantitation of the peroxidase activities; 5250 ± 0.00 U/L was recorded against Raoultella ornithinolytica OKOH-1 and 5833 ± 0.00 U/L against Ensifer adhaerens NWODO-2. The ligninolytic and dye decolourization properties of Raoultella ornithinolytica OKOH-1 and Ensifer adhaerens NWODO-2 marks for novelty particularly, as dyes with arene substituents were decolourized. Consequently, the potentials for the industrial applicability of these test bacterial strains abound as there is a dearth of information on organisms with such potentials.

Lignin peroxidase functionalities and prospective applications

Ligninolytic extracellular enzymes, including lignin peroxidase, are topical owing to their high redox potential and prospective industrial applications. The prospective applications of lignin peroxidase span through sectors such as biorefinery, textile, energy, bioremediation, cosmetology, and dermatology industries. The litany of potentials attributed to lignin peroxidase is occasioned by its versatility in the degradation of xenobiotics and compounds with both phenolic and non-phenolic constituents. Over the years, ligninolytic enzymes have been studied however; research on lignin peroxidase seems to have been lagging when compared to other ligninolytic enzymes which are extracellular in nature including laccase and manganese peroxidase. This assertion becomes more pronounced when the application of lignin peroxidase is put into perspective. Consequently, a succinct documentation of the contemporary functionalities of lignin peroxidase and, some prospective applications of futuristic relevance has been advanced in this review. Some articulated applications include delignification of feedstock for ethanol production, textile effluent treatment and dye decolourization, coal depolymerization, treatment of hyperpigmentation, and skin-lightening through melanin oxidation. Prospective application of lignin peroxidase in skin-lightening functions through novel mechanisms, hence, it holds high value for the cosmetics sector where it may serve as suitable alternative to hydroquinone; a potent skin-lightening agent whose safety has generated lots of controversy and concern.