Continental Climate Changes on the Occurrence of Aflatoxin Producing <em>Aspergillus species:</em> Review

Review Article

Austin J Microbiol. 2018; 4(1): 1021.

Continental Climate Changes on the Occurrence of Aflatoxin Producing Aspergillus species: Review

Kanyi KJ*

Faculty of Science and Informatics, University of Szeged, Hungary

*Corresponding author: Kihika Joseph Kanyi, Faculty of Science and Informatics, University of Szeged, 6728 Othalmi Diaklakasok Szeged, Hungary

Received: May 03, 2018; Accepted: July 18, 2018; Published: July 25, 2018

Abstract

Most countries that occur in the middle latitudes (40° to 55° North) experience continental climates that are described to have large annual temperature differences, mostly with warm to very hot (and often humid) summers and sometimes cold or severely cold winters. The emission of Green House Gases that mainly include the CO2 as a result of increased human activities has contributed to global warming with high temperatures being recorded in continental regions in Europe. As the climate changes, increased aflatoxin contamination of plants and farm produce in parts of Europe has been recorded from the main aflatoxin producing fungi belonging to the aspergilli genus that include: Aspergillus flavus and A .parasiticus respectively. A flavus has been recorded to occur in large amounts where temperatures are about 28°C optimum for their growth and 28°C - 30°C for aflatoxin production. The consumption of aflatoxins has many detrimental effects to plants, animals and human life where humans suffer from increased nutritional deficiencies, immune suppression and hepatocellular carcinoma.

Aflatoxin B1 is the most potent and it’s abundantly produced by the fungal toxigenic strains. To control the spread of these mycotoxin fungal strains due to the climate changes in the continental zones, proper mitigation purposes to curb the harsh climatic conditions has to be effectively implemented and adhered to ensure that safe agriculture is practiced to produce mycotoxin free farm produce required to feed the increasing human population globally.

Keywords: Continental climate; Climate changes; Aflatoxin; Aspergilli; Toxigenic; Mitigation

Abbreviations

IPCC: Intergovernmental Panel on Climate Change; CO2: Carbon Di Oxide; EFSA: European Food Safety Authority; °C: Degrees Celsius; TLC: Thin Layer Chromatography; HPLC: High Performance Layer Chromatography; GC: Gas Chromatography; ELISA: Enzyme-linked Immunosorbent Assay; EU: European Union; GHG: Green House Gas

Introduction

Continental climates refers to the climates that are often described to have a significant annual variation in temperature characterized by the hot summers and cold winters. These climates tend to occur in the middle latitudes (40° to 55° North), where the prevailing winds blow overland, and these regions lack water bodies like the oceans and seas that can moderate the temperatures. Continental climates occur mostly in the Northern Hemisphere, where there are large land masses required for this type of climate to develop. Most of northern and northeastern China, eastern and south-eastern Europe, central and south-eastern Canada, and the central and upper eastern united States have this type of climate. In Continental climates, they experience continuous precipitation in the warmer months and it tends to be moderate in amount. A portion of the annual precipitation falls as snow during cold winters, and snow often remains on the ground for more than a month. Furthermore, the summer seasons experience thunderstorms and frequent cool temperatures but in these climates the summer weather is observed to be more stable than winter weather. However, according to [1], it has been found out that conditions adverse to the growth of many plants like (drought stress, temperature stress, stress induced by pest attack, poor nutrient status, etc.) encourages the fungal partner to develop more than under conditions that are favorable to the plant with the expectation of greater production of mycotoxins.

Changes in Continental Climates

Continental climates are experiencing changes and there is now unequivocal evidence that climate change is taking place, and it is very likely, that increases in atmospheric greenhouse gas concentrations resulting from the increased human activities mainly through atmospheric pollution are causing global warming. In Europe the effects of climate changes are already being observed and further changes in climate are projected to take place in the future. During the 20th century, there was an increase in average annual surface temperature experienced in Europe of about 0.8°C, which was accompanied with an increased rate of warming over time. It was found out that the 1990s were the warmest on record [2]. The warming experienced has been stronger in most of the continental climatic regions in winter than in summer. An increase in warm extremes has been observed rather than a decrease in cold extremes [3].

The IPCC [4] (Eds) reports that the world’s land ecosystems act as a major sink in the contemporary global carbon cycle and, therefore it alleviates the rise of atmospheric CO2 concentrations from global CO2 emissions and as a consequence there is an overall effect on climate change.

Europe will also be increasingly confronted with the impact of climate change. Climate change will come about gradually as a result of increases in average temperatures and changes in precipitation levels. However, in the shorter term extreme weather changes will be felt which will constitute a major short-term challenge but the main impact of these changes will be felt in the long term partly because of the presence of multiple complex factors that influence the carbon balance of terrestrial ecosystems including climate change, land-use and land-cover change (forest regrowth, fire suppression etc.) and nitrogen deposition, and CO2 increase in the atmosphere [5].

In their report, European Food Safety Authority (EFSA, 2007), evidenced the emerging issue of potential aflatoxin contamination of several plants that include corn, almonds and pistachios that were grown in areas of Southern Europe, due to the changes in the subtropical climate occurring in some recent years.

The quantity of aflatoxin producing fungi that is associated with crops and soils varies with different climates. These fungi compete poorly under cool conditions and the quantity of Aspergillus flavus in cool areas (temperature minima below 20°C) is usually low compared to warmer regions (temperature minima N25°C) where aflatoxinproducers are always commonly found throughout soils, air, and on crop surfaces [6,7]. The crops that are grown in warm climates have greater likelihood of infection by aflatoxin producers and in some regions, infection only occurs when temperatures increase in association with drought conditions [8,9].

Aspergillus flavus as an Aflatoxin Producer

The Aspergillus genus is well known for its ability to secrete a variety of secondary biologically active chemical compounds that include antibiotics, mycotoxins, immune-suppressants, and cholesterol lowering agents [10,11]. Aflatoxins are the most thoroughly studied mycotoxins produced predominantly by the main causative agent Aspergillus flavus (Figure 1). According to Maren [12], A. flavus has a broad host range as an opportunistic and a very common pathogen of soil, plants, animals and insects and it causes storage rots in numerous crops and it produces the highly regulated mycotoxin, aflatoxin B1.

Citation: Kanyi KJ. Continental Climate Changes on the Occurrence of Aflatoxin Producing Aspergillus species: Review. Austin J Microbiol. 2018; 4(1): 1021.