Yak (Bos Grunniens) Stomach Lysozyme: Molecular Cloning, Expression and its Antibacterial Activities

Entomopathogenic potential of bacteria associated with soil-borne nematodes and insect immune responses to their infection

Soil-borne nematodes establish close associations with several bacterial species. Whether they confer benefits to their hosts has been investigated in only a few nematode-bacteria systems. Their ecological function, therefore, remains poorly understood. In this study, we isolated several bacterial species from rhabditid nematodes, molecularly identified them, evaluated their entomopathogenic potential on Galleria mellonella larvae, and measured immune responses of G. mellonella larvae to their infection. Bacteria were isolated from Acrobeloides sp., A. bodenheimeri, Heterorhabditis bacteriophora, Oscheius tipulae, and Pristionchus maupasi nematodes. They were identified as Acinetobacter sp., Alcaligenes sp., Bacillus cereus, Enterobacter sp., Kaistia sp., Lysinibacillus fusiformis, Morganella morganii subsp. morganii, Klebsiella quasipneumoniae subsp. quasipneumoniae, and Pseudomonas aeruginosa. All bacterial strains were found to be highly entomopathogenic as they killed at least 53.33% G. mellonella larvae within 72h post-infection, at a dose of 106 CFU/larvae. Among them, Lysinibacillus fusiformis, Enterobacter sp., Acinetobacter sp., and K. quasipneumoniae subsp. quasipneumoniae were the most entomopathogenic bacteria. Insects strongly responded to bacterial infection. However, their responses were apparently little effective to counteract bacterial infection. Our study, therefore, shows that bacteria associated with soil-borne nematodes have entomopathogenic capacities. From an applied perspective, our study motivates more research to determine the potential of these bacterial strains as biocontrol agents in environmentally friendly and sustainable agriculture.

Applications of Lysozyme, an Innate Immune Defense Factor, as an Alternative Antibiotic

Lysozyme is a ~14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi. Three main different types of lysozymes are known: the c-type (chicken or conventional type), the g-type (goose type), and the i-type (invertebrate type). It has long been the subject of several applications due to its antimicrobial properties. The problem of antibiotic resistance has stimulated the search for new molecules or new applications of known compounds. The use of lysozyme as an alternative antibiotic is the subject of this review, which covers the results published over the past two decades. This review is focused on the applications of lysozyme in medicine, (the treatment of infectious diseases, wound healing, and anti-biofilm), veterinary, feed, food preservation, and crop protection. It is available from a wide range of sources, in addition to the well-known chicken egg white, and its synergism with other compounds, endowed with antimicrobial activity, are also summarized. An overview of the modified lysozyme applications is provided in the form of tables.

Molecular Cloning and Characterization of a New C-type Lysozyme Gene from Yak Mammary Tissue

Milk lysozyme is the ubiquitous enzyme in milk of mammals. In this study, the cDNA sequence of a new chicken-type (c-type) milk lysozyme gene (YML), was cloned from yak mammary gland tissue. A 444 bp open reading frames, which encodes 148 amino acids (16.54 kDa) with a signal peptide of 18 amino acids, was sequenced. Further analysis indicated that the nucleic acid and amino acid sequences identities between yak and cow milk lysozyme were 89.04% and 80.41%, respectively. Recombinant yak milk lysozyme (rYML) was produced by Escherichia coli BL21 and Pichia pastoris X33. The highest lysozyme activity was detected for heterologous protein rYML5 (M = 1,864.24 U/mg, SD = 25.75) which was expressed in P. pastoris with expression vector pPICZαA and it clearly inhibited growth of Staphylococcus aureus. Result of the YML gene expression using quantitative polymerase chain reaction showed that the YML gene was up-regulated to maximum at 30 day postpartum, that is, comparatively high YML can be found in initial milk production. The phylogenetic tree indicated that the amino acid sequence was similar to cow kidney lysozyme, which implied that the YML may have diverged from a different ancestor gene such as cow mammary glands. In our study, we suggest that YML be a new c-type lysozyme expressed in yak mammary glands that plays a role as host immunity.

Molecular cloning, recombinant protein expression, tissue distribution and functional analysis of a new c-type lysozyme from Lezhi black goat rumen

Zhang, P., Wang, Y., Jiang, M., Zhu, L., Li, J., Luo, M., Ren, H. and Liu, L. 2014. Molecular cloning, recombinant protein expression, tissue distribution and functional analysis of a new c-type lysozyme from Lezhi black goat rumen. Can. J. Anim. Sci. 94: 27–34. Three major distinct types of lysozymes have been identified in the animal kingdom and most lysozymes cloned from ruminants belong to the chicken-type (c-type). In this study, a new c-type lysozyme gene, named LZRLyz, was cloned and sequenced from the Lezhi black goat rumen. The LZRLyz cDNA has a 444 bp open reading frame (ORF) encoding a 147 amino acid polypeptide. The encoded polypeptide is predicted to have an 18 amino acid signal peptide, and a 129 amino acid mature protein with an isoelectric point (pI) of 6.08. The LZRLyz amino acid sequence shares 70.27% identity with the Capra hircus blood lysozyme and is grouped with other ruminants c-type lysozymes using the phylogenetic tree estimated by Neighbor-Jointing method. The recombinant expressed LZRLyz protein (pET-rLZR) shows a molecular mass of ∼33 kDa, which is consistent with the predicted fusion protein molecular mass and shows antimicrobial activity. Quantitative real-time RT-PCR analyses revealed that LZRLyz transcripts are expressed in all tested tissues with the predominant expression being observed in rumen and the weakest one in spleen. Results of this study suggest that the LZRLyz gene represents a new c-type lysozyme gene that likely functions in Lezhi black goat host immunity and digestive systems.