Yongtao Zhu

• PhD
• Professor (Associate) at Xi’an Jiaotong-Liverpool University

Flavobacterium psychrophilum causes bacterial cold-water disease (BCWD) in salmonids and other fish, resulting in substantial economic losses in aquaculture worldwide. The mechanisms F. psychrophilum uses to cause disease are poorly understood. Despite considerable effort, most strains of F. psychrophilum have resisted attempts at genetic manipulat...

The Type-IX secretion system (T9SS) is a nanomachinery utilized by bacterial pathogens to facilitate infection. The system is regulated by a signaling cascade serving as its activation switch. A pivotal member in this cascade, the response regulator protein PorX, represents a promising drug target to prevent the secretion of virulence factors. Here...

The Type-IX secretion system (T9SS) is a nanomachinery utilized by bacterial pathogens to facilitate infection. The system is regulated by a signaling cascade serving as its activation switch. A pivotal member in this cascade, the response regulator protein PorX, represents a promising drug target to prevent the secretion of virulence factors. Here...

Many bacteria belonging to the phylum Bacteroidetes move on solid surfaces, called gliding motility. In our previous study with the Bacteroidetes gliding bacterium Flavobacterium johnsoniae , we proposed a helical loop track model, where adhesive SprB filaments are propelled along a helical loop on the cell surface. In this study, we observed the g...

Many bacteria belonging to the phylum Bacteroidetes move on solid surfaces, which is called gliding motility. In our previous study with the Bacteroidetes gliding bacterium Flavobacterium johnsoniae , we proposed a helical loop track model, where adhesive SprB filaments are propelled along a left-handed closed helical loop on the cell surface. Atta...

Flavobacterium columnare causes columnaris disease in wild and cultured freshwater fish and is a major problem for sustainable aquaculture worldwide. The F. columnare type IX secretion system (T9SS) secretes many proteins and is required for virulence. The T9SS component GldN is required for secretion and for gliding motility over surfaces. Genetic...

The ability to produce membrane projections in the form of tubular membrane extensions (MEs) and membrane vesicles (MVs) is a widespread phenomenon among bacteria. Despite this, our knowledge of the ultrastructure of these extensions and their associated protein complexes remains limited. Here, we surveyed the ultrastructure and formation of MEs an...

Energy conversion is a fundamental process of all organisms, realized by specialized protein complexes, one of which is alternative complex III (ACIII). ACIII is a functional analogue of well-known mitochondrial complex III, but operates according to a different, still unknown mechanism.

The F. johnsoniae gliding motility adhesin SprB is delivered to the cell surface by the type IX secretion system (T9SS) and is rapidly propelled along the cell by the motility machinery. How this 6,497-amino-acid protein interacts with the secretion and motility machines is not known. Fusion of the C-terminal 218 amino acids of SprB to a foreign ca...

Macroalgae contribute substantially to primary production in coastal ecosystems. Their biomass, mainly consisting of polysaccharides, is cycled into the environment by marine heterotrophic bacteria using largely uncharacterized mechanisms. Here we describe the complete catabolic pathway for carrageenans, major cell wall polysaccharides of red macro...

Flavobacterium columnare , a member of the phylum Bacteroidetes , causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. Many members of the phylum Bacteroidetes use type IX secretion systems (T9SSs) to secrete enzymes, adhesins, and proteins involved in gliding mot...

Cellulolytic microorganisms play important roles in global carbon cycling and have evolved diverse strategies to digest cellulose. Some are ‘generous,’ releasing soluble sugars from cellulose extracellularly to feed both themselves and their neighbors. The gliding soil bacterium Cytophaga hutchinsonii exhibits a more ‘selfish’ strategy. It digests...

Flavobacterium johnsoniae and many related bacteria secrete proteins across the outer membrane using the type IX secretion system (T9SS). Proteins secreted by T9SSs have amino-terminal signal peptides for export across the cytoplasmic membrane by the Sec system and carboxy-terminal domains (CTDs) targeting them for secretion across the outer membra...

Comprehension of the degradation of macroalgal polysaccharides suffers from the lack of genetic tools for model marine bacteria, despite their importance for coastal ecosystem functions. We developed such tools for Zobellia galactanivorans, an algae-associated flavobacterium that digests many polysaccharides, including alginate. These tools were us...

Background Chitin is the second most abundant polysaccharide on earth and as such a great target for bioconversion applications. The phylum Bacteroidetes is one of nature’s most ubiquitous bacterial lineages and is essential in the global carbon cycle with many members being highly efficient degraders of complex carbohydrates. However, despite thei...

Importance: The bacterium Cytophaga hutchinsonii digests crystalline cellulose by an unknown mechanism. It lacks processive cellobiohydrolases that are often involved in cellulose digestion. Critical cellulolytic enzymes were identified by genetic analyses. Intracellular (periplasmic) nonprocessive endoglucanases performed an important role in cel...

Flavobacterium columnare is a Gram-negative bacterial pathogen that causes columnaris disease of freshwater fish. Flavobacterium columnare strain C#2 was isolated from a diseased warm-water fish and is typed as genomovar II. The genome consists of a single 3.33-Mb circular chromosome with 2,689 predicted coding genes.

Gliding motility is common in members of the phylum Bacteroidetes, including Flavobacterium johnsoniae and Cellulophaga algicola. F. johnsoniae gliding has been extensively studied and involves rapid movement of the cell-surface adhesin SprB. Genetic analysis of C. algicola allowed a comparative analysis of gliding. Sixty-three HimarEm1-induced mut...

Cytophaga hutchinsonii, a member of the phylum Bacteroidetes, employs a novel collection of cell-associated proteins to digest crystalline cellulose. Other Bacteroidetes rely on cell surface proteins related to the starch utilization system (Sus) proteins SusC and SusD to bind oligosaccharides and import them across the outer membrane for further d...

The family Cytophagaceae, which spans at least 25 genera and 80 species, is one of the largest families in the phylum Bacteroidetes. The members of the family are diverse in terms of physiology and habitat, but some common properties can be identified. Members of the family Cytophagaceae are commonly isolated from marine, freshwater, and terrestria...

Cytophaga hutchinsonii glides rapidly over surfaces and employs a novel collection of cell-associated proteins to digest crystalline cellulose. HimarEm1 transposon mutagenesis was used to isolate a mutant with an insertion in CHU_0170 (sprP) that was partially deficient in gliding motility and was unable to digest filter paper cellulose. SprP is si...

Cytophaga hutchinsonii, a member of the phylum Bacteroidetes, actively digests crystalline cellulose. C. hutchinsonii encodes nine predicted cell-associated endoglucanases, but it lacks genes encoding predicted cellobiohydrolases. Proteins predicted to bind crystalline cellulose are also lacking. The absence of these proteins suggests that C. hutch...

The gliding bacterium Cytophaga hutchinsonii employs a novel collection of proteins to digest cellulose. Analysis of the C. hutchinsonii genome revealed nine predicted endoglucanases but surprisingly, no obvious cellobiohydrolases or proteins with recognizable type A cellulose binding domains predicted to bind crystalline cellulose. Like many membe...

The phylum Bacteroidetes is large and diverse, with rapid gliding motility and the ability to digest macromolecules associated with many genera and species. Recently, a novel protein secretion system, the Por secretion system (PorSS), was identified in two members of the phylum, the gliding bacterium Flavobacterium johnsoniae and the nonmotile oral...

Cytophaga hutchinsonii is an abundant aerobic cellulolytic bacterium that rapidly digests crystalline cellulose in a contact-dependent manner. The different roles of various predicted glycoside hydrolases and the detailed mechanism used by C. hutchinsonii in cellulose digestion are, however, not known. In this study, an endoglucanase belonging to g...

The invention relates to a method which uses yeast for preparing soluble Beta-1, 3-oligoglucoside. The method comprises alkali pretreatment, acid hydrolysis as well as separation and purification, wherein, the separation and purification are as follows: after the soluble Beta-1, 3-oligoglucoside prepared from acid hydrolysis is dissolved, separatio...

The invention relates to a method for breaking walls of beer yeast cells by utilizing a microbial enzyme system, which comprises the steps of preparation of a crude enzyme preparation, and pretreatment and enzymolysis of the yeast cells, and belongs to the field of biotechnology. The method for breaking the walls of the beer yeast is simple to oper...

Flavobacterium johnsoniae is capable of secreting enzymes which can efficiently hydrolyze yeast cell wall. Preliminary analysis revealed the presence of glucanase, chintinase and protease activities in its culture supernatant. A laminarinase was purified from the extracellular components of F. johnsoniae through several isolation steps including io...

Cytophaga hutchinsonii is an abundant aerobic cellulolytic soil bacterium utilizing very few substrates as sole carbon and energy sources. In this study, growth of C. hutchinsonii on different substrates including crystalline cellulose, regenerated amorphous cellulose (RAC) as well as soluble sugars including cellodextrins was analyzed. Soluble sug...

There is a great diversity for cellulolytic microbes in nature and the strategies they use to digest cellulose. In addition to the cultured cellulolytic microbes, there are still a great number of microbes being not readily culturable in natural environments, which may represent great potential for identifying novel cellulases and their encoding ge...