Probiotic Effects of a Marine Purple Non-Sulfur Bacterium, Rhodovulum sulfidophilum KKMI01, on Kuruma Shrimp (Marsupenaeus japonicus)

Exploring the role and mechanism of potential probiotics in mitigating the shrimp pathogens

Shrimp aquaculture has rapidly developed into a significant industry worldwide, providing not only financial gain and high-quality food but also tens of thousands of trained and competent workers. Frequent diseases are now regarded as a significant risk factor for shrimp aquaculture, as they have the potential to significantly reduce shrimp production and result in economic losses. Over the years various traditional methods including the use of antibiotics have been followed to control diseases yet unsuccessful. Probiotic is considered potential supplements for shrimps during farming, they may also act beneficially as disease control and increased production. Probiotics are described as a live microbial supplement that benefits the host by modifying the microbial population associated with the host and its ambient. The present state of research about probiotics demonstrates notable impacts on the immune defences of the host's gastrointestinal system, which play a crucial role in safeguarding against diseases and managing inflammation inside the digestive tract. In the past ten years, many studies on probiotics have been published. However, there is a lack of information about the processes by which probiotics exert their effects in aquaculture systems, with only limited elucidations being offered. This study explores the variety of procedures behind the positive effects of probiotics in shrimp culture. These mechanisms include the augmentation of the immune system, control of growth, antagonistic action against pathogens, competitive exclusion, and modification of the gut microbiota. Mechanisms involved in the probiotic mode of action are mostly interlinked. This provides a greater understanding of the importance of probiotics in shrimp culture as an environmentally friendly practice.

Acute effects of the environmental probiotics Rhodobacter sphaeroides on intestinal bacteria and transcriptome in shrimp Penaeusvannamei

In recent years, a substantial number of studies have been dedicated to exploring the potential benefits of probiotics in aquaculture. Rhodobacter sphaeroides can be used in aquaculture-related environmental bioremediation, and its protein is also used as a feed additive in Penaeus vannamei culture. To investigate the effects of releasing R. sphaeroides as environmental probiotics on P. vannamei, we employed 16S rRNA gene and mRNA transcriptome sequencing. Our study focused on assessing alterations in intestinal bacteria and intestinal gene expression in P. vannamei, establishing correlations between them. Our findings revealed a significant increase in the relative abundances of Rhodobacter, Paracoccus, Sulfitobacter, and other bacterial OTUs within the intestinal bacterial community. Additionally, we observed enhanced complexity and stability in the intestinal bacterial correlation network, indicating improved synergy among bacteria and reduced competition. Moreover, the introduction of R. sphaeroides resulted in the down-regulation of certain immune genes and the up-regulation of genes linked to growth and metabolism in the intestinal tissues of P. vannamei. Importantly, we identified a noteworthy correlation between the changes in intestinal bacteria and these alterations in intestinal tissue gene expressions. By conducting analyses of the intestinal bacterial community and intestinal tissue transcriptome, this study revealed the effects of releasing R. sphaeroides as sediment probiotics in P. vannamei culture water. These results serve as vital scientific references for the application of R. sphaeroides in P. vannamei aquaculture.

Therapeutic Potential of Marine Probiotics: A Survey on the Anticancer and Antibacterial Effects of Pseudoalteromonas spp

Due to the increasing limitations and negative impacts of the current options for preventing and managing diseases, including chemotherapeutic drugs and radiation, alternative therapies are needed, especially ones utilizing and maximizing natural products (NPs). NPs abound with diverse bioactive primary and secondary metabolites and compounds with therapeutic properties. Marine probiotics are beneficial microorganisms that inhabit marine environments and can benefit their hosts by improving health, growth, and disease resistance. Several studies have shown they possess potential bioactive and therapeutic actions against diverse disease conditions, thus opening the way for possible exploitation of their benefits through their application. Pseudoalteromonas spp. are a widely distributed heterotrophic, flagellated, non-spore-forming, rod-shaped, and gram-negative marine probiotic bacteria species with reported therapeutic capabilities, including anti-cancer and -bacterial effects. This review discusses the basic concepts of marine probiotics and their therapeutic effects. Additionally, a survey of the anticancer and antibacterial effects of Pseudoalteromonas spp. is presented. Finally, marine probiotic production, advances, prospects, and future perspectives is presented.

Recent progress in the use of purple non-sulfur bacteria as probiotics in aquaculture

The use of probiotics in aquaculture is widely recognized as an ecological and cost-effective approach to raising healthy, pathogen-tolerant aquatic animals, including fish and shrimp. In particular for shrimp, probiotics are viewed as a promising countermeasure to the recent severe damage to the shrimp industry by bacterial and viral pathogens. Purple non-sulfur bacteria (PNSB) are Gram-negative, non-pathogenic bacteria with wide application potential in agriculture, wastewater treatment, and bioenergy/biomaterials production. In aquaculture, lactic bacteria and Bacillus are the major probiotic bacteria used, but PNSB, like Rhodopseudomonas and Rhodobacter, are also used. In this review, we summarize the previous work on the use of PNSB in aquaculture, overview the previous studies on the stimulation of innate immunity of shrimp by various probiotic microorganisms, and also share our results in the probiotic performance of Rhodovulum sulfidophilum KKMI01, a marine PNSB, which showed a superior effect in promotion of growth and stimulation of immunity in shrimp at a quite low concentration of 1 × 10³ cfu (colony forming unit)/ml in rearing water.

Commensal Bacillus siamensis LF4 induces antimicrobial peptides expression via TLRs and NLRs signaling pathways in intestinal epithelial cells of Lateolabrax maculatus

Antimicrobial peptides (AMPs) play an important role in modulating intestinal microbiota, and our previous study showed that autochthonous Baccilus siamensis LF4 could shape the intestinal microbiota of spotted seabass (Lateolabrax maculatus). In the present study, a spotted seabass intestinal epithelial cells (IECs) model was used to investigate whether autochthonous B. siamensis LF4 could modulate the expression of AMPs in IECs. And then, the IECs were treated with active, heat-inactivated LF4 and its supernatant to illustrate their AMPs inducing effects and the possible signal transduction mechanisms. The results showed that after 3 h of incubation with 10⁸ CFU/mL B. siamensis LF4, lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), glutamic propylic transaminase (GPT) activities in supernatant decreased significantly and obtained minimum values, while supernatant alkaline phosphatase (AKP) activity, β-defensin protein level and IECs Na⁺/K⁺-ATPase activity, AMPs (β-defensin, hepcidin-1, NK-lysin, piscidin-5) genes expression increased significantly and obtained maximum values (P < 0.05). Further study demonstrated that the active, heat-inactivated LF4 and its supernatant treatments could effectively decrease the LDH, GOT, and GPT activities in IECs supernatant, increase AKP activity and β-defensin (except LF4 supernatant treatment) protein level in IECs supernatant and Na⁺/K⁺-ATPase and AMPs genes expression in IECs. Treatment with active and heat-inactivated B. siamensis LF4 resulted in significantly up-regulated the expressions of TLR1, TLR2, TLR3, TLR5, NOD1, NOD2, TIRAP, MyD88, IRAK1, IRAK4, TRAF6, TAB1, TAB2, ERK, JNK, p38, AP-1, IKKα, IKKβ and NF-κB genes. Treatment with B. siamensis LF4 supernatant also resulted in up-regulated these genes, but not the genes (ERK, JNK, p38, and AP-1) in MAPKs pathway. In summary, active, heat-inactivated and supernatant of B. siamensis LF4 can efficiently induce AMPs expression through activating the TLRs/NLRs-MyD88-dependent signaling, active and heat-inactivated LF4 activated both the downstream MAPKs and NF-κB pathways, while LF4 supernatant only activated NF-κB pathway.

Special Issue “Biotechnological Application of Photosynthetic Bacteria”

This Special Issue aims to contribute to the current knowledge in the field and promote the practical application of photosynthetic bacteria (PSB) biotechnology [...]

Effects of Seed Bio-Priming by Purple Non-Sulfur Bacteria (PNSB) on the Root Development of Rice

The effects of seed bio-priming (seed soaking) with purple non-sulfur bacteria (PNSB) on the grain productivity and root development of rice were examined by a field study and laboratory experiments, respectively. Two PNSB strains, Rhodopseudomonas sp. Tsuru2 and Rhodobacter sp. Tsuru3, isolated from the paddy field of the study site were used for seed bio-priming. For seed bio-priming in the field study, the rice seeds were soaked for 1 day in water containing a 1 × 10⁵ colony forming unit (cfu)/mL of PNSB cells, and the rice grain productivities at the harvest time were 420, 462 and 504 kg/are for the control, strain Tsuru2-primed, and strain Tsuru3-primed seeds, respectively. The effects of seed priming on the root development were examined with cell pot cultivation experiments for 2 weeks. The total root length, root surface area, number of tips and forks were evaluated with WinRhizo, an image analysis system, and strains Tsuru2- and Tsuru3-primed seeds showed better root development than the control seeds. The effects of seed priming with the dead (killed) PNSB cells were also examined, and the seed priming with the dead cells was also effective, indicating that the effects were attributed to some cellular components. We expected the lipopolysaccharide (LPS) of PNSB as the effective component of PNSB and found that seed priming with LPS of Rhodobacter sphaeroides NBRC 12203 (type culture) at the concentrations of 5 ng/mL and 50 ng/mL enhanced the root development.