Microbial Communication with Humans

Chapter 20 - Microbial Communication: Bacteria/Bacteria and Bacteria/Host

Chapter 16 - Microbial Communication: Bacteria–Bacteria and Bacteria–Host

Caves are a challenging environment for many organisms to inhabit, and many cave-dwelling animals are endemic to particular cave systems. Microorganisms in caves have been shown to have a high biosynthetic capacity, likely as a result of intense biological interactions to deal with resource scarcity. Although cave salamanders have been studied extensively in other parts of the world, they have received relatively little attention in Mexico. Declines of some cave-dwelling species may be due to outbreaks of fungal disease, and a better understanding of their cutaneous microbiome could help with future conservation efforts in the face of disease outbreaks. We characterized the cutaneous microbiome of 11 cave-dwelling Mexican salamanders and their relatives from surface environments using high-throughput 16S amplicon sequencing. We expected cave salamanders to have a more diverse microbiome containing more bacteria with potential antifungal capacity compared to forest salamanders. We also estimated networks of associations between bacteria to test the hypothesis that there are more positive associations in caves. Finally, we used a bioinformatic approach to see if bacteria in caves potentially have more metabolic pathways associated with microbial communication as a result of more intense biological interactions in caves. Although we do not find higher skin bacterial diversity in caves compared to forests, we do find differences in microbiome composition between environments, more positive associations between bacteria, and a slightly higher number of metabolic pathways associated with microbial communication in caves. Our results provide some support for an impact of the cave environment on the skin microbiome of Mexican salamanders.

Chapter 3 - Microbial communications in Gram-positive and Gram-negative bacteria

Graphical Abstract The cover picture shows the colonies of bioluminescent bacteria that Bonnie Bassler uses to decipher the molecular mechanism governing microbial chemical communication. Also shown are several key molecules involved in microbial chemical communication. As highlighted throughout this special issue, the work of Bonnie Bassler on microbial chemical communication has strong impact on both basic and applied microbiology. The cover picture was designed by Julia van Kessel and photograph taken by Zach Donnell.

This work examines the communication interactions of water suppliers and health authorities with the general public regarding microbial source water quality for recreational and drinking water. We compare current approaches to risk communication observable in British Columbia (BC), Canada, with best practices derived from the communications literature, finding significant gaps between theory and practice. By considering public views and government practices together, we identify key disconnects, leading to the conclusion that at present, neither the public's needs nor public health officials' goals are being met. We find: (1) there is a general lack of awareness and poor understanding by the public of microbial threats to water and the associated health implications; (2) the public often does not know where to find water quality information; (3) public information needs are not identified or met; (4) information sharing by authorities is predominantly one-way and reactive (crisis-oriented); and (5) the effectiveness of communications is not evaluated. There is a need for both improved public understanding of water quality-related risks, and new approaches to ensure information related to water quality reaches audiences. Overall, greater attention should be given to planning and goal setting related to microbial water risk communication.

Rule-based computing system for microbial interactions and communications: Evolution in virtual bacterial populations

Despite the rising interest in microbial communication, only few studies relate to mycorrhization and the pool of potential morphogenic substances produced by the surrounding soil community. Here, we investigated the effect exerted by the C18 - ketone β-apo-13-carotenone, D'orenone, on the ectomycorrhizal basidiomycete Tricholoma vaccinum and its symbiosis with the economically important host tree, spruce (Picea abies). D'orenone is an early intermediate in the biosynthesis of morphogens in sexual development of mucoromycetes, the trisporoids. In the ectomycorrhizal fungus T. vaccinum, D'orenone increased the production and/or release of the phytohormone indole-3-acetic acid (IAA) which had been proposed to be involved in the mutual symbiosis. The induced expression of the fungal aldehyde dehydrogenase, Ald5 is associated with IAA synthesis and excretion. In the host tree, D'orenone modulated root architecture by increasing lateral root length and hypertrophy of root cortex cells, likely via changed IAA concentrations and flux. Thus, we report for the first time on carotenoid metabolites from soil fungi affecting both ectomycorrhizal partners. The data imply a complex network of functions for secondary metabolites which act in an inter-kingdom signalling in soil.

BackgroundReciprocal exchanges of metabolites between phytoplankton and bacteria influence the fitness of these microorganisms which ultimately shapes the productivity of marine ecosystems. Recent evidence suggests that plant growth-promoting hormones may be key metabolites within mutualistic phytoplankton-bacteria partnerships, but very little is known about the diversity of plant growth-promoting hormones produced by marine bacteria and their specific effects on phytoplankton growth. Here, we aimed to investigate the capacity of marine bacteria to produce 7 plant growth-promoting hormones and the effects of these hormones on Actinocyclus sp. growth.ResultsWe examined the plant growth-promoting hormone synthesis capabilities of 14 bacterial strains that enhance the growth of the common diatom Actinocyclus. Plant growth-promoting hormone biosynthesis was ubiquitous among the bacteria tested. Indeed all 14 strains displayed the genomic potential to synthesise multiple hormones, and mass-spectrometry confirmed that each strain produced at least 6 out of the 7 tested plant growth-promoting hormones. Some of the plant growth-promoting hormones identified here, such as brassinolide and trans-zeatin, have never been reported in marine microorganisms. Importantly, all strains produced the hormone indole-3 acetic acid (IAA) in high concentrations and released it into their surroundings. Furthermore, indole-3 acetic acid extracellular concentrations were positively correlated with the ability of each strain to promote Actinocyclus growth. When inoculated with axenic Actinocyclus cultures, only indole-3 acetic acid and gibberellic acid enhanced the growth of the diatom, with cultures exposed to indole-3 acetic acid exhibiting a two-fold increase in cell numbers.ConclusionOur results reveal that marine bacteria produce a much broader range of plant growth-promoting hormones than previously suspected and that some of these compounds enhance the growth of a marine diatom. These findings suggest plant growth-promoting hormones play a large role in microbial communication and broaden our knowledge of their fuctions in the marine environment.4YJWCKdNErspcm2bUDNM6tVideo

The Application Potential of Synthetic Biology in Microbial Communication

At near 50 years of the discovery of microcins, this article highlights the pivotal—but under-recognised—influence of Spanish biochemist Carlos Asensio (1925–1982) in contemporary microbiology, featuring the epistemological, sociological, and cultural impact of his scientific achievements. At a time when the intestinal microbiome is central to current biomedical research, it is due to emphasise his role in the establishment of new scientific fields that are now considered fundamental. Despite his premature death at the peak of his conceptual and experimental creativity, many of his ideas about microbial communication in complex communities inspired a generation of researchers and opened new topics reach to this day. Asensio was also a trailblazer in Spain, advocating for fundamental research within the socio-economic context of his time. He foresaw the shift towards what is now termed the knowledge-based bioeconomy, recognised the need for multidisciplinary research teams, and advocated integration science into societal and political agendas. These facets became evident during his research on microcins, low molecular weight bioactive compounds produced by enterobacteria. These molecules were hypothesised as mediators of microbial interactions in the human gut and were considered potential new antibiotics and even antitumoral agents. His research mobilised young talent and attracted unprecedented resources in Spain during the late 1970s–early 1980s. It underscored the medical value of microbial ecology and exemplified the benefits of collaboration between academia and industry. Asensio played a pivotal role in the emergence of molecular microbial ecology as a research discipline and its foundational and applied significance in biotechnology.

Undigested dietary and endogenous proteins, as well as unabsorbed amino acids, can move from the terminal part of the ileum into the large intestine, where they meet a dense microbial population. Exfoliated cells and mucus released from the large intestine epithelium also supply nitrogenous material to this microbial population. The bacteria in the large intestine luminal fluid release amino acids from the available proteins, and amino acids are then used for bacterial protein synthesis, energy production, and in other various catabolic pathways. The resulting metabolic intermediaries and end products can then accumulate in the colorectal fluid, and their concentrations appear to depend on different parameters, including microbiota composition and metabolic activity, substrate availability, and the capacity of absorptive colonocytes to absorb these metabolites. The aim of the present review is to present how amino acid-derived bacterial metabolites can affect microbial communication between both commensal and pathogenic microorganisms, as well as their metabolism, physiology, and growth.

Food fermentation is driven by microorganisms, which usually coexist as multispecies biofilms. The activities and interactions of functional microorganisms and pathogenic bacteria in biofilms have important implications for the quality and safety of fermented foods. It was verified that the biofilm lifestyle benefited the fitness of microorganisms in harsh environments and intensified the cooperation and competition between biofilm members. This review focuses on multispecies biofilm formation, microbial interactions and communication in biofilms, and the application of multispecies biofilms in food fermentation. Microbial aggregation and adhesion are important steps in the early stage of multispecies biofilm formation. Different biofilm-forming abilities and strategies among microorganisms lead to several types of multispecies biofilm formation. Thespatial distribution of multispecies biofilms reflects microbial interactions and biofilm function. Then, we discuss the intrinsic factors and external manifestations of multispecies biofilm system succession. Several typical interspecies cooperation and competition modes and mechanisms of microbial communication were reviewed in this review. The main limitations of the studies included in this review are the relatively small number of studies of biofilms formed by functional microorganisms during fermentation and the lack of directevidenceforthe formation process of multispecies biofilms and microbial interactions and communication within biofilms. This review aims to provide the food industry with a sufficient understanding of multispecies biofilms in food fermentation. Practical Application: Meanwhile, it offers a reference value for better controlling and utilizing biofilms during food fermentation process, and the improvement of the yield, quality, and safety of fermented products including Chinese Baijiu, cheeese,kefir, soy sauce, kombucha, and fermented olive.

Microbial secondary metabolites (SMs) have long been viewed as a significant source of novel pharmaceutical and agrochemical molecules. With the increasing availability of genomic data, numerous biosynthetic gene clusters (BGCs) have been discovered. Despite the presence of tens of thousands of BGCs that can theoretically produce extremely diverse SMs, many gene clusters remain in a silent state under axenic culture conditions. Co-culture is a promising research approach as it stimulates the expression of cryptic BGCs to produce novel metabolites and also mimics natural interspecies interactions in a laboratory environment. In recent years, the roles of SMs in microbial communication have caught the attention of researchers and our understanding of microbes and their production of remarkable SMs has improved. SMs may be extensively involved in a variety of communication events among microorganisms. We herein summarize certain representative findings in the field of chemical communication involving SMs in co-culture systems.

Light-mediated “conversation” among microorganisms