Further Studies on the Microbial Content ( Endomicrobiology , Endobacteriology ) of Fruit and Vegetable Crops : the Study Continues !

Previous studies in our lab over the past several years on fruits and vegetables have identified various species of microorganisms, primarily bacteria, that appear to be endemic to the inner flesh/pulp of many crops. While consumption of these fruits and vegetables usually do not cause disease to the public in general, there may be a greater risk to immunocompromised individuals, especially upon consumption of crops that are eaten raw/uncooked or only slightly cooked. In this study, we examined various fruits, herbs, and vegetables that we had not previously examined for the presence of such microorganisms, and many/most of the crops we examined did indeed contain endemic microorganisms in their inner flesh/pulp. Our findings are herewith reported.


Introduction
Over the past several years have identified numerous species of microorganisms that inhabit the surface and/or flesh/pulp of various fruit and vegetable crops; terms we have coined topomicrobiology and endomicrobiology, respectively (Edelman and Lin 2011, 1013, 2016).These microorganisms were generally considered to be non-pathogenic commensal species, although in certain instances, such as immunocompromised individuals, some of these species can theoretically become opportunistic and pathogenic.We have continued this study to crops that we had not previously tested, and we hereby present the results in this report.Among the crops currently investigated are fruits and vegetables, edible mushrooms/fungi, aromatic/culinary herbs and spices, and some uncommon and tropical fruits and vegetables.

Materials & Methods
The microbial content of crops was isolated and identified using a combination of the methods previously described (Edelman and Lin (2011, 2013, 2016).These included inserting sterile cotton-tipped applicators into the flesh/pulp and/or homogenizing the crops or small sections of crops into blenders/food processors for one minute.Tryptic Soy agar plates (or in some cases, Saboraud agar plates, for fungal cultivation ) were then swabbed with cotton tipped applicators and allowed to grow at room temperature for several days.Plates were then shipped to AvistaPharma Solutions, 104 Gold Street, Agawam, Massachusetts, 01001, U.S.A. for species identification using DNA sequence analysis.

Results and Discussion
While some crops were found to be sterile/microorganism-free in the inner flesh/pulp, many were indeed found to harbor bacteria and in some cases fungi.The bacterial/fungal content of such crops are shown in Table 1.Although most of the fruits and vegetables tested did contain one or several species of bacteria and fungi in their inner pulp/flesh, in general consumption of these crops with these organisms do not seem to cause human diseases.Many of these microorganisms are probably destroyed by hydrochloric acid and enzymes throughout our digestive system, while others are destroyed through the cooking process.However, immunocompromised individuals are most likely to be at a higher risk for infection, especially when these crops are eaten raw.In our previous study we noted numerous diseases that the microorganisms found in crops were capable of causing (Edelman and Lin, 2016), although their presence in fruits and vegetables do not necessarily cause infection.The purpose of this and our previous reports are merely to alert the consumers that these microorganisms are indeed present in such foods.Many consumers erroneously assume that if fruits and vegetables are washed before consumption they are automatically sterile, which we have shown not to be the case.
Another question which arises often is whether the organisms identified in the crops studied are pathogenic at all.While it is not the scope or objective of this report to investigate the possible pathogenicity of every organism identified, we have randomly selected a few species and canvassed the literature.We noted that almost all organisms identified in the fruits and vegetables can, under certain conditions, such as being immunocompromised, cause diseases and bacteremia.Providencia rettgeri, for example, (found in this study in watercress and green olives), have been found to cause bacteremia and bacteriuria (Wie, 2015).Bacillus flexus, (found in this study in dried lily flowers), has been found in an outbreak in a tertiary burn center (Ucar et al, 2016).Acidovorax, (found in this study in Nance yellow cherry), has been found in a case of sepsis (Shetty, et al., 2005).Curtobacterium flaccumfaciens, (found in this study in red currants), has been found in human infections (Funke, et al., 2005).Enterobacter pyrinus,( found in this study in soursop/guanabana), has also been found in human infections (Baylis et al., 2011).Myroides odorotimimus (found in this study fresh, undried oregano), has been found to cause bacteremia in a diabetic patient (Endicott et al., 2015) as well as soft tissue infections, septic shock, and pneumonia in other patients (Benedetti, et al., 2011).Ignatzschineria indica, (found in this study in the herb sage), has been implicated in Myiasis (Barker, et al., 2014).Infections involving Acinetobacter baumanii, (found in this study in lemon grass and catnip), have also been reported (Peleg et al., 2008).
Pseudomonas chlororaphis, (found in this study in Swiss Chard), has been implicated in various human infections as reported by Faccone, et al., (2014).Further investigation of the literature on the other microbial species present in the fruits and vegetables used in this study will most likely also identify some cases of human infection.Again, this does not necessarily imply that such crops are dangerous to human health in general, but that they may, under certain circumstances, pose a risk to immunocompromised individuals.

Conclusions
The main idea of this report is to inform the public and scientific community that while some fruits and vegetables do seem to be sterile, many or most are not sterile, even after washing, as microorganisms are indeed present in their inner flesh/pulp.We plan to continue this investigation on other fruits and vegetables in the near

Table 1 .
Microbial species found in the inner flesh/pulp of crops tested in this study

Table 2 .
Fruit and Vegetable species in which the inner flesh/pulp was test:d and found to be sterile: