We and herbivores eat endophytes.

Health depends on the diet and a vegetal diet promotes health by providing fibres, vitamins and diverse metabolites. Remarkably, plants may also provide microbes. Fungi and bacteria that reside inside plant tissues (endophytes) seem better protected to survive digestion; thus, we investigated the reported evidence on the endophytic origin of some members of the gut microbiota in animals such as panda, koala, rabbits and tortoises and several herbivore insects. Data examined here showed that some members of the herbivore gut microbiota are common plant microbes, which derived to become stable microbiota in some cases. Endophytes may contribute to plant fibre or antimetabolite degradation and synthesis of metabolites with the plethora of enzymatic activities that they display; some may have practical applications, for example, Lactobacillus plantarum found in the intestinal tract, plants and in fermented food is used as a probiotic that may defend animals against bacterial and viral infections as other endophytic-enteric bacteria do. Clostridium that is an endophyte and a gut bacterium has remarkable capabilities to degrade cellulose by having cellulosomes that may be considered the most efficient nanomachines. Cellulose degradation is a challenge in animal digestion and for biofuel production. Other endophytic-enteric bacteria may have cellulases, pectinases, xylanases, tannases, proteases, nitrogenases and other enzymatic capabilities that may be attractive for biotechnological developments, indeed many endophytes are used to promote plant growth. Here, a cycle of endophytic-enteric-soil-endophytic microbes is proposed which has relevance for health and comprises the fate of animal faeces as natural microbial inoculants for plants that constitute bacterial sources for animal guts.

Metatranscriptomic Analysis of the Bacterial Symbiont Dactylopiibacterium carminicum from the Carmine Cochineal Dactylopius coccus (Hemiptera: Coccoidea: Dactylopiidae).

The scale insect Dactylopius coccus produces high amounts of carminic acid, which has historically been used as a pigment by pre-Hispanic American cultures. Nowadays carmine is found in food, cosmetics, and textiles. Metagenomic approaches revealed that Dactylopius spp. cochineals contain two Wolbachia strains, a betaproteobacterium named Candidatus Dactylopiibacterium carminicum and Spiroplasma, in addition to different fungi. We describe here a transcriptomic analysis indicating that Dactylopiibacterium is metabolically active inside the insect host, and estimate that there are over twice as many Dactylopiibacterium cells in the hemolymph than in the gut, with even fewer in the ovary. Albeit scarce, the transcripts in the ovaries support the presence of Dactylopiibacterium in this tissue and a vertical mode of transmission. In the cochineal, Dactylopiibacterium may catabolize plant polysaccharides, and be active in carbon and nitrogen provisioning through its degradative activity and by fixing nitrogen. In most insects, nitrogen-fixing bacteria are found in the gut, but in this study they are shown to occur in the hemolymph, probably delivering essential amino acids and riboflavin to the host from nitrogen substrates derived from nitrogen fixation.

Metatranscriptomics and nitrogen fixation from the rhizoplane of maize plantlets inoculated with a group of PGPRs.

Plant roots are inhabited by a large diversity of microbes, some of which are beneficial for the growth of plants and known as plant growth promoting rhizobacteria (PGPR). In this work, we designed a multispecies inoculum of PGPRs containing Rhizobium phaseoli, Sinorhizobium americanum and Azospirillum brasilense nitrogen-fixing strains and other plant-growth promoting bacteria such as Bacillus amyloliquefaciens and Methylobacterium extorquens. We evaluated the effect of this group of bacteria on the growth of one-month-old maize plants. The multispecies inoculum exerted a beneficial effect on maize plants that was greater than that obtained with single-bacteria. Using the same multispecies inoculant, acetylene reduction was recorded in 5-day-old roots indicating active nitrogen fixation by bacteria in maize. Azospirillum nitrogen fixation was lower than that obtained with the multispecies inoculum. We focused on the analysis of R. phaseoli gene expression in presence of other PGPRs. Many R. phaseoli up- regulated genes in roots in the presence of other bacteria are hypothetical, showing our poor knowledge of bacteria-bacteria interactions. Other genes indicated bacterial nutrient competition and R. phaseoli stress. Differentially expressed transcriptional regulators were identified that may be key in bacteria-bacteria interaction regulation. Additionally, gene expression was analyzed from Azospirillum but not from sinorhizobia and methylobacteria due to the low number of transcripts obtained from maize roots. The metatranscriptomic analysis from maize roots showed expression of Azospirillum nif genes in the presence of PGPR bacteria. Our hypothesis is that other bacteria stimulate Azospirillum capacity to fix nitrogen and this should be further explored.